H-Transforms Theory and Applications
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H-Transforms Theory and Applications
ANALYTICAL METHODS AND SPECIAL FUNCTIONS An International Series of Monographs in Mathematics FOUNDING EDITOR: A.P. Prudnikov (Russia) SERIES EDITORS: C.F. Dunkl (USA), H.-J. Glaeske (Germany) and M. Saigo (Japan)
∫∑ Volume 1 Series of Faber Polynomials P.K. Suetin Volume 2 Inverse Spectral Problems for Linear Differential Operators and Their Applications V.A. Yurko Volume 3 Orthogonal Polynomials in Two Variables P.K. Suetin Volume 4 Fourier Transforms and Approximations A.M. Sedletskii Volume 5 Hypersingular Integrals and Their Applications S. Samko Volume 6 Methods of the Theory of Generalized Functions V.S. Vladimirov Volume 7 Distribution, Integral Transforms and Applications W. Kierat & U. Sztaba Volume 8 Bessel Functions and Their Applications B. Korenev Volume 9 H-Transforms: Theory and Applications A.A. Kilbas and M. Saigo
H-Transforms Theory and Applications
Anatoly A. Kilbas Belarusian State University, Belarus
Megumi Saigo Fukuoka University, Japan
CHAPMAN & HALL/CRC A CRC Press Company Boca Raton London New York Washington, D.C.
TF1593_discl(7x10).fm Page 1 Monday, February 2, 2004 11:02 AM
Library of Congress Cataloging-in-Publication Data Saigo, Megumi H-transforms: theory and applications / Megumi Saigo, Anatoly A. Kilbas. p. cm. -- (Analytical methods and special functions ; 9) Includes bibliographical references and index. ISBN 0-415-29916-0 (alk. paper) 1. H-functions. 2. Integral transforms. I Kilbas, A.A. (Anatolii Aleksandrovich) II. Title. III. Series. QA353.H9S35 2004 515’.723—dc22
2003070007
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CONTENTS Preface Chapter 1. De nition, Representations and Expansions of the H -Function 1.1. De nition of the H -Function 1.2. Existence and Representations 1.3. Explicit Power Series Expansions 1.4. Explicit Power-Logarithmic Series Expansions 1.5. Algebraic Asymptotic Expansions at In nity 1.6. Exponential Asymptotic Expansions at In nity in the Case > 0; 1.7. 1.8. 1.9. 1.10. 1.11.
a = 0 Exponential Asymptotic Expansions at In nity in the Case n = 0 Algebraic Asymptotic Expansions at Zero Exponential Asymptotic Expansions at Zero in the Case < 0; a = 0 Exponential Asymptotic Expansions at Zero in the Case m = 0 Bibliographical Remarks and Additional Information on Chapter 1
Chapter 2. Properties of the H -Function 2.1. Elementary Properties 2.2. Di erentiation Formulas 2.3. Recurrence Relations and Expansion Formulas 2.4. Multiplication and Transformation Formulas 2.5. Mellin and Laplace Transforms of the H -Function 2.6. Hankel Transforms of the H -Function 2.7. Fractional Integration and Di erentiation of the H -Function 2.8. Integral Formulas Involving the H -Function 2.9. Special Cases of the H -Function 2.10. Bibliographical Remarks and Additional Information on Chapter 2 v
ix 1 1 3 5 7 9 12 17 19 21 24 25 31 31 33 36 41 43 48 51 56 62 67
vi
Contents
Chapter 3. H -Transform on the Space L;2 3.1. The H -Transform and the Space L;r 3.2. The Mellin Transform on L;r 3.3. Some Auxiliary Operators 3.4. Integral Representations for the H -Function 3.5. L;2-Theory of the General Integral Transform 3.6. L;2-Theory of the H -Transform 3.7. Bibliographical Remarks and Additional Information on Chapter 3 Chapter 4. H -Transform on the Space L;r 4.1. L;r -Theory of the H -Transform When a = = 0 and Re() = 0 4.2. L;r -Theory of the H -Transform When a = = 0 and Re() < 0 4.3. L;r -Theory of the H -Transform When a = 0; > 0 4.4. L;r -Theory of the H -Transform When a = 0; < 0 4.5. L;r -Theory of the H -Transform When a > 0 4.6. Boundedness and Range of the H -Transform When a1 > 0 and a2 > 0 4.7. Boundedness and Range of the H -Transform When a > 0 and a1 = 0 4.8. 4.9. 4.10. 4.11.
or a2 = 0 Boundedness and Range of the H -Transform When a > 0 and a1 < 0 or a2 < 0 Inversion of the H -Transform When = 0 Inversion of the H -Transform When = 0 Bibliographical Remarks and Additional Information on Chapter 4 6
Chapter 5. Modi ed H -Transforms on the Space L;r 5.1. Modi ed H -Transforms 5.2. H 1-Transform on the Space L;r 5.3. H 2-Transform on the Space L;r 5.4. H ; -Transform on the Space L;r 5.5. H 1; -Transform on the Space L;r 5.6. H 2; -Transform on the Space L;r 5.7. Bibliographical Remarks and Additional Information on Chapter 5
71 71 72 74 77 82 86 90 93 93 97 100 104 107 108 112 115 118 121 126 133 133 134 140 145 150 155 160
Contents
Chapter 6. G-Transform and Modi ed G-Transforms on the Space L;r 6.1. G-Transform on the Space L;r 6.2. Modi ed G-Transforms 6.3. G1-Transform on the Space L;r 6.4. G2-Transform on the Space L;r 6.5. G; -Transform on the Space L;r 6.6. G1; -Transform on the Space L;r 6.7. G2; -Transform on the Space L;r 6.8. Bibliographical Remarks and Additional Information on Chapter 6 Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r 7.1. Laplace Type Transforms 7.2. Meijer and Varma Integral Transforms 7.3. Generalized Whittaker Transforms 7.4. D -Transforms 7.5. 1F 1-Transforms 7.6. 1F 2-Transforms 7.7. 2F 1-Transforms 7.8. Modi ed 2F 1-Transforms 7.9. The Generalized Stieltjes Transform 7.10. pF q -Transform 7.11. The Wright Transform 7.12. Bibliographical Remarks and Additional Information on Chapter 7 Chapter 8. Bessel Type Integral Transforms on the Space L;r 8.1. The Hankel Transform 8.2. Fourier Cosine and Sine Transforms 8.3. Even and Odd Hilbert Transforms 8.4. The Extended Hankel Transform 8.5. The Hankel Type Transform 8.6. Hankel{Schwartz and Hankel{Cli ord Transforms
vii 165 165 173 175 179 183 188 193 197 203 203 206 212 216 219 223 227 233 238 240 246 251 263 263 270 272 276 280 285
viii
8.7. 8.8. 8.9. 8.10. 8.11. 8.12. 8.13. 8.14.
The Transform Y The Struve Transform The Meijer K -Transform Bessel Type Transforms The Modi ed Bessel Type Transform The Generalized Hardy{Titchmarsh Transform The Lommel{Maitland Transform Bibliographical Remarks and Additional Information on Chapter 8
Bibliography Subject Index Author Index Symbol Index
Contents
289 299 307 313 321 325 337 342 357 377 381 385
PREFACE This book deals with integral transforms involving the so-called H -functions as kernels, or H -transforms, and their applications. The H -function is de ned by the Mellin{Barnes type integral with the integrand containing products and quotients of the Euler gamma functions. Such a function generalizes most of the known special functions, which means that almost all integral transforms can be put into the form of H -transforms. Another generalization, though a special case of H -transforms, was proposed as the G-transform of the integral transform with the Meijer G-function as a kernel; this generalization includes the classical Laplace and Hankel transforms, the Riemann{Liouville fractional integral transforms, the even and odd Hilbert transforms, the integral transforms with the Gauss hypergeometric function, and others. However, there are transforms that cannot be reduced to a G-transform but can be put into the form of H -transforms: the modi ed Laplace and Hankel transforms, the Erdelyi{Kober type fractional integration operators, the modi ed transforms with the Gauss hypergeometric function as kernel, the Bessel type integral transforms, the Mittag-Leer type integral transforms and others. The classical Fourier, Laplace, Mellin and Hankel transforms have been widely used in various problems of mathematical physics and applied mathematics. Such applications in various elds have been covered in the books by I.N. Sneddon [1]{[5] and in his survey paper [6]. These transforms are usually involved in solutions of boundary value problems for models of ordinary and partial di erential equations that characterize certain processes. There are many other problems whose solutions cannot be represented by the above classical integral transforms but may be characterized by integral transforms with various special functions as kernels. Among the integral transforms with special function kernels, the integral transforms involving functions of hypergeometric and Bessel types, as well as fractional integral transforms, have often arisen in applied problems. For example, integral transforms with Bessel type kernels are important in many axially symmetric problems. When we want to get solutions that are regular on the axis of symmetry, such a solution involves the Hankel transform with the Bessel function of the rst kind in the kernel (I.N. Sneddon [4]). When the solution has a singularity near the axis of symmetry, the Struve transform and its reciprocal containing Neumann and Struve functions are involved in this solution (P.G. Rooney [4]). The interest in integral transforms with special function kernels is also motivated by the desire to study the corresponding integral equations of the rst kind and of the so-called dual and triple equations that are also encountered in applications. The results in these elds were presented in a series of books including the above books by I.N. Sneddon. In particular, the results in these elds obtained by methods of fractional calculus were characterized in Chapter 7 of the book by S.G. Samko, A.A. Kilbas and O.I. Marichev [1]. We also note the book by H.M. Srivastava and R.G. Buschman [4], which contains many examples of the convolution integral equations with special function kernels. ix
x
Preface
Integral transforms with various special function kernels have been investigated by many authors. They have basically been studied in L1 and L2 -spaces or in certain spaces of tested and generalized functions. The results in the former were presented as examples in the books by E.C. Titchmarsh [3], I.N. Sneddon [1], and V.A. Ditkin and A.P. Prudnikov [1] together with the theory of classical transforms. These publications involved the one-dimensional integral transform, while the book by Yu.A. Brychkov, H.-J. Glaeske, A.P. Prudnikov and Vu Kim Tuan [1] was devoted to the multidimensional case. The results for integral transforms in spaces of tested and generalized functions appeared in the books by Yu.A. Brychkov and A.P. Prudnikov [1] and R.S. Pathak [11]. It should be noted that many new results, obtained recently in the theory of integral transforms with special function kernels and with more general H -function kernels, were not re ected in the monographs in the above literature. As for H -transforms, only some results in the theory of these transforms in L1 - and L2 -spaces were presented in Chapter 3 of the book by H.M. Srivastava, K.C. Gupta and S.P. Goyal [1]. The interest of the present authors in H -transforms was motivated by generalizations of the integral transforms with hypergeometric and Bessel type kernels, which are involved in solutions of integral and di erential equations of fractional order. Investigation of more general integral transforms with H -function kernels allows us to look more clearly at the problems with these equations, which are basically related to the mapping properties and asymptotic behavior of their solutions. These problems were solved by extending the range of parameters of the H -transforms. Such a result was obtained, in turn, by the extension of the parameters of the H -function under its asymptotic behavior near zero and in nity. In this book we present the results from the theory of integral transforms with H -function kernels in weighted spaces of Lebesgue r-summable functions L;r (for real and 1 5 r 5 1, see Section 3.1) on the half-axis R+ = (0; 1). Properties such as the boundedness, including the one-to-one property of the map, the representation, and the ranges of H -transforms in L;r -spaces are studied together with their inversion formulas. Applications are given to integral transforms with kernels involving the Meijer G-function and special functions of the hypergeometric and Bessel types. Our investigations are based on the method of Mellin multipliers developed by Rooney [2] and on the asymptotic expansions of the H -function at zero and in nity. The latter were previously proved by the authors by developing the approach suggested by B.L.J. Braaksma [1]. These asymptotic estimates allow us not only to characterize the L;r -theory of the H -transforms and integral transforms with special functions as kernels but also to extend and more precisely characterize the known statements in the theory of the H -function. When = 1=r, the spaces L;r coincide with the spaces Lr (R+ ) of r-summable functions on R+, and one may deduce the Lr -theory of the integral transforms with H - and G-functions and special functions of hypergeometric and Bessel types as kernels from our statements proved for the L;r -spaces. These results generalize the known assertions on the boundedness properties of integral transforms with special function kernels in L2- and Lr -spaces (1 < r < 1) in the main. The book consists of eight chapters. The results presented in the main body of the chapters are, as a rule, given with complete proofs. Distinctive historical survey sections complete every
Preface
xi
chapter, and are given in Sections 1.11, 2.10, 3.7, 4.11, 5.7, 6.8, 7.12 and 8.14. These sections provide historical comments on the content of the previous chapter and contain discussions and formulations of the results closely related to the subject matter of the chapter but not included in the main text. The rst two chapters contain various results from the theory of the H -function. Chapter 1 deals with the existence and representations of the H -function, its explicit power and powerlogarithmic expansions, and the asymptotic expansions near zero and in nity. Chapter 2 is devoted to other properties of the H -function such as elementary formulas, di erentiation and recurrence relations, expansion and multiplication formulas and the transformation formulas of Mellin, Laplace and Hankel transforms, and fractional integro-di erentiation. General integral formulas involving the H -function are considered together with the special cases. Chapters 3{5 present the L;r -theory of integral transforms with H -function kernels. The mapping properties such as the boundedness, the one-to-one properties of the map, and the representation of the H -transforms in L;2 -space are proved in Chapter 3. These results are extended to L;r -space with arbitrary r (1 5 r 5 1) in Chapter 4, in which the range H(L;r ) is also characterized and inversion relations are given. Chapter 5 deals with L;r -theory of the modi ed integral transform with H -function kernels that are obtained from H -transforms by elementary transforms of translation, dilatation, re ection, and multiplication by a power function. The last three chapters contain the results from the L;r -theory of integral transforms with special function kernels. The integral transforms with the Meijer G-function as kernel are considered in Chapter 6 together with the modi ed G-transforms. Chapter 7 is devoted to the hypergeometric type integral transforms such as the Laplace and Stieltjes type transforms, the transforms that contain Whittaker and parabolic cylinder functions, hypergeometric functions and Wright functions as kernels. Bessel type integral transforms are studied in Chapter 8, in which Hankel type transforms including the Bessel function of the rst kind and its generalizations in the kernels are treated, as well as cosine and sine transforms, even and odd Hilbert transforms, and transforms with Neumann, Struve and Macdonald functions, modi ed Macdonald functions and Lommel{Maitland functions as kernels. We note that the asymptotic estimates in Chapter 1 may be extended considerably beyond the known range of parameters for the H -function. Furthermore, the statements in Chapter 2 clarify the known assertions, and the results from L;r -theory of the H -transforms in Chapters 3 and 4 allow us to generalize the known investigations for the modi ed H - and G-transforms in Chapters 5 and 6 as well as for the integral transforms with kernel functions of hypergeometric and Bessel types in Chapters 7 and 8. We also note that most of the results in Chapters 5{7 were not published previous to our articles. This book re ects the above investigations made by ourselves and in cooperation with other mathematicians. More detailed information can be found in the historical survey sections. We must note that the L;2 -theory results of the H -transforms and their inversions presented in Chapter 3 and Sections 4.9{4.10 were obtained together with S.A. Shlapakov, most of the results on the L;r -theory of the H -transforms in Sections 4.1{4.8 were obtained together with H.-J. Glaeske and S.A. Shlapakov, and some of the results in Chapter 8 were proved together with H.-J. Glaeske, J.J. Trujillo, J. Rodriguez, M. Rivero, B. Bonilla, L. Rodriguez and
xii
Preface
A.N. Borovco. We also note that the boundedness, the representation, and the ranges of H transforms in L;r -spaces were investigated by J.J. Betancor and C. Jerez Diaz, independently. The bibliography consists of 578 entries, published up to 2002. We hope that we have listed all publications concerning one-dimensional integral transforms with H -function kernels. However, it cannot be considered a complete bibliography of the investigations in the elds of H -function and one-dimensional integral transforms with special function kernels. Interested readers may nd many additional references in the books by A.M. Mathai and R.K. Saxena [2] and H.M. Srivastava, K.C. Gupta and S.P. Goyal [1] for the former, and in the books by H.M. Srivastava and R.G. Buschman [4], S.G. Samko, A.A. Kilbas and O.I. Marichev [1, Chapter 7], Yu.A. Brychkov and A.P. Prudnikov [1], R.S. Pathak [11], A.I. Zayed [1] and L. Debnath [1] for the latter. One can also nd references for works on multidimensional integral transforms in the book by Yu.A. Brychkov, H.-J. Glaeske, A.P. Prudnikov and Vu Kim Tuan [1]. We would like to express our deep gratitude to the late Professor Anatolii Platonovich Prudnikov for his interest in our investigations and valuable discussions. The preparation of this book was supported in part by the Belarusian Fundamental Research Fund, and by the Science Research Promotion Fund from the Japan Private School Promotion Foundation.
Chapter 1 DEFINITION, REPRESENTATIONS AND EXPANSIONS OF THE H -FUNCTION 1.1. De nition of the
H -Function
For integers m; n; p; q such that 0 5 m 5 q; 0 5 n 5 p; for ai ; bj 2 C with C ; the set of complex m;n (z ) numbers, and for i ; j 2 R+ = (0; 1) (i = 1; 2; ; p; j = 1; 2; ; q ); the H -function Hp;q is de ned via a Mellin{Barnes type integral in the form " # (a ; ) (ai ; i )1;p # p p m;n z Hp;q z (bj ; j )1;q (bq ; q ) " # Z (a ; ); ; (a ; ) 1 1 p p 1 ;s m;n Hp;q z = 2i Hm;n p;q (s)z ds L (b1; 1); ; (bq ; q)
m;n(z ) H m;n Hp;q p;q
"
(1.1.1)
with m;n Hm;n p;q (s) Hp;q
"
m
Y
=
j =1 p Y i=n+1
Here
" (ai; i )1;p # (ap; p) # m;n s Hp;q s (bj ; j )1;q (bq ; q )
;(bj + j s)
;(ai + i s)
n
Y
;(1 ; ai ; i s)
i=1 q Y
j =m+1
;(1 ; bj ; j s)
:
p z ;s = exp[;sflog jz j + i arg zg]; z 6= 0; i = ;1;
(1.1.2)
(1.1.3)
where log jz j represents the natural logarithm of jz j and arg z is not necessarily the principal value. An empty product in (1.1.2), if it occurs, is taken to be one, and the poles (1.1.4) bjl = ;b j ; l (j = 1; ; m; l = 0; 1; 2; ) j of the gamma functions ;(bj + j s) and the poles
aik = 1 ; ai + k (i = 1; ; n; k = 0; 1; 2; ) i
1
(1.1.5)
2
Chapter 1. De nition; Representations and Expansions of the H -function
of the gamma functions ;(1 ; ai ; i s) do not coincide:
i(bj + l) 6= j (ai ; k ; 1) (i = 1; ; n; j = 1; ; m; k; l = 0; 1; 2; ):
(1.1.6)
L in (1.1.1) is the in nite contour which separates all the poles bjl in (1.1.4) to the left and all the poles aik in (1.1.5) to the right of L; and has one of the following forms: (i) L = L;1 is a left loop situated in a horizontal strip starting at the point ;1 + i'1
and terminating at the point ;1 + i'2 with ;1 < '1 < '2 < +1; (ii) L = L+1 is a right loop situated in a horizontal strip starting at the point +1 + i'1 and terminating at the point +1 + i'2 with ;1 < '1 < '2 < +1: (iii) L = Li 1 is a contour starting at the point ; i1 and terminating at the point
+ i1; where 2 R = (;1; +1). m;n (z ) depend on the numbers a ; ; ; ; a and a The properties of the H -function Hp;q 1 2 which are expressed via m; n; p; q; ai ; i (i = 1; 2; ; p) and bj ; j (j = 1; 2; ; q ) by the following relations:
a =
n
X
i=1 q X
i ;
p
X
i +
m
X
j ;
q
X
j ;
i=n+1 j =1 j =m+1 p X = j ; i ; j =1 i=1 p q Y Y = ;i i j j ; i=1 j =1 q p X X = bj ; ai + p ;2 q ; j =1 i=1 p m X X a1 = j ; i ; j =1 i=n+1 q n X X a2 = i ; j ; i=1 j =m+1 a1 + a2 = a ; a1 ; a2 = ; q p m n X X X X = bj ; bj + ai ; ai ; j =1 j =m+1 i=1 i=n+1
c = m + n ; p +2 q :
(1.1.7) (1.1.8) (1.1.9) (1.1.10) (1.1.11) (1.1.12) (1.1.13) (1.1.14) (1.1.15)
An empty sum in (1.1.7), (1.1.8), (1.1.10){(1.1.12), (1.1.14) and an empty product in (1.1.9), if they occur, are taken to be zero and one, respectively.
3
1.2. Existence and Representations
1.2. Existence and Representations
m;n (z ) may be recognized by the convergence of the integral The existence of the H -function Hp;q in (1.1.1) which depends on the asymptotic behavior of the function Hm;n p;q (s) in (1.1.2) at in nity. Such an asymptotic is based on the following relations for the gamma function ;(z ) of z = x + iy (x; y 2 R): p (1.2.1) j;(x + iy)j 2jxjx;1=2e;x;[1;sign(x)]y=2 (jxj ! 1) and p (1.2.2) j;(x + iy)j 2jyjx;1=2e;x;jyj=2 (jyj ! 1); which are proved by using the Stirling relation (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 1.18(2)]) p (1.2.3) ;(z ) 2e(z;1=2) log z e;z (z ! 1):
Remark 1.1. The relation 1.18(6) in Erdelyi, Magnus, Oberhettinger and Tricomi [1] needs correction with the addition of the multiplier ex in the left-hand side and must be replaced by x+jyj=2 jy j1=2;x = p2: (1.2.4) lim j ;( x + iy ) j e jyj!1 The following assertions follow from (1.1.2), (1.2.1) and (1.2.2).
Lemma 1.1. For t; 2 R; there hold the estimates e Hm;n p;q (t + i ) A t
with
q
and
j
j
ai );1=2e;Re(ai ) Re( i
e Hm;n p;q (t + i ) B jtj
with
j =1 p Yh i=1
ttRe() (t ! +1)
jRe(b );1=2e;Re(b )
Y h
A = (2)c eq;m;n
;t
q
jtj
i
i=1
i
i
e[ j +Im(bj )]
;
;jtjjtjRe() (t ! ;1)
i jRe(bj );1=2e;Re(bj )
j =1 p Yh
i=1 q Y
e[ +Im(a )]
j =m+1
Y h
B = (2)c eq;m;n
n
iY
(1.2.5)
ai);1=2 e;Re(ai ) Re( i
p
Y
i=n+1 m
i Y
j =1
(1.2.7)
e[ +Im(a )] i
(1.2.6)
i
e[ j +Im(bj )]
:
(1.2.8)
4
Chapter 1. De nition; Representations and Expansions of the H -function
Lemma 1.2. For ; t 2 R; there holds the estimate +Re() e;[jtja +Im()sign(t)]=2 (jtj ! 1) Hm;n p;q ( + it) C jtj uniformly in on any bounded interval in R; where
C
p q ;c ; ;Re() Y 1=2;Re(ai ) Y Re(bj );1=2 c = (2 ) e i j i=1 j =1
(1.2.9) (1.2.10)
and is de ned in (1.1.14). Let '1; '2; 2 R and l1; l2 and l be the lines
l1 = ft + i'1 : t 2 Rg; l2 = ft + i'2 : t 2 Rg ('1 < '2); l = f + it : t 2 Rg: From Lemmas 1.1 and 1.2 we obtain the following asymptotic relations at in nity for the integrand in (1.1.1) on the lines l1; l2 and l :
e jtj jzj jtj jtjRe() jtj (s = t + i'i 2 li ; i = 1; 2)
;s ' arg z Hm;n p;q (s)z Bie i
(1.2.11)
as t ! ;1;
e ;t t tRe() t jzj (s = t + i'i 2 li ; i = 1; 2)
;s ' arg z Hm;n p;q (s)z Ai e i
(1.2.12)
as t ! +1; and ;s ;[ log jzj+Im()sign(t)=2]jtj +Re() e;jtja =2+t arg z Hm;n p;q (s)z C1e
(1.2.13)
(s = + it 2 l ) as jtj ! 1. Here A1 and A2; B1 and B2 are given in (1.2.6) and (1.2.8) with being replaced by '1 and '2 ; respectively, and C1 by (1.2.10) with being replaced by . The conditions for the existence of the H -function follow by virtue of these relations.
Theorem 1.1. Let a; ; and be given in (1:1:7){(1:1:10): Then the H -function
m;n (z ) de ned by (1:1:1) makes sense in the following cases: Hp;q
L = L;1 ; > 0; z 6= 0;
(1.2.14)
L = L;1 ; = 0; 0 < jz j < ;
(1.2.15)
L = L;1 ; = 0; jz j = ; Re() < ;1;
(1.2.16)
L = L+1 ; < 0; z 6= 0;
(1.2.17)
L = L+1 ; = 0; jz j > ;
(1.2.18)
5
1.3. Explicit Power Series Expansions
L = L+1 ; = 0; jz j = ; Re() < ;1;
(1.2.19)
L = Li 1 ; a > 0; jarg z j <
(1.2.20)
a ; z 6= 0; 2 L = Li 1 ; a = 0; + Re() < ;1; arg z = 0; z 6= 0:
(1.2.21)
Remark 1.2. The results of Theorem 1.1 in the cases (1.2.16), (1.2.19) and (1.2.21) are more precise than those in Prudnikov, Brychkov and Marichev [3, 8.3.1]. The estimate (1.2.11) holds for t ! ;1 uniformly on the set which has a positive distance to the points bjl in (1.1.4) and which does not contain any point to the right of L;1 . The same is true for the estimate (1.2.12) being valid for t ! +1 uniformly on the set with a positive distance to the points aik in (1.1.5) and containing no point to the left of L+1 . Therefore using Theorem 1.1 and the theory of residues, we obtain the following result:
Theorem 1.2. (i) If the conditions (1:1:6) and (1:2:14) or (1:2:15) are satis ed; then
the H -function (1:1:1) is an analytic function of z and m;n (z ) = Hp;q
m X 1 X j =1 l=0
Res s=b
h
jl
i
;s Hm;n p;q (s)z ;
(1.2.22)
where bjl are given in (1:1:4): (ii) If the conditions (1:1:6) and (1:2:17) or (1:2:18) are satis ed; then the H -function (1:1:1) is an analytic function of z and m;n (z ) = ; Hp;q
n X 1 X
i=1 k=0
sRes =a
ik
h
i
;s Hm;n p;q (s)z ;
(1.2.23)
where aik are given in (1:1:5): (iii) If the conditions in (1:1:6) and (1:2:20) are satis ed; then the H -function (1:1:1) is an analytic function of z in the sector j arg z j < a =2.
1.3. Explicit Power Series Expansions In view of the cases (i) and (ii) of Theorem 1.2 we may establish the series representations m;n (z ); in the respective cases of the poles bjl in (1.1.4) of the gamma functions ;(bj + for Hp;q j s) (j = 1; ; m) being simple:
j (bi + k) 6= i (bj + l) (i 6= j ; i; j = 1; ; m; k; l = 0; 1; 2; ) (1.3.1) and the poles aik in (1.1.5) of ;(1 ; ai + i s) (i = 1; ; n) also being simple: j (1 ; ai + k) 6= i (1 ; aj + l) (i 6= j ; i; j = 1; ; n; k; l = 0; 1; 2; ): (1.3.2) First we consider the former case. To apply Theorem 1.2(i) we evaluate the residues of m;n Hp;q (s)z;s at the points s = bjl. For this, we use the property in Marichev [1, (3.39)], that
6
Chapter 1. De nition; Representations and Expansions of the H -function
is, in a neighborhood of the poles z = ;k (k = 0; ;1; ;2; ) the gamma function ;(z ) can be extended in powers of z + k = : i kh 1 + (1 + k ) + O 2 ( ! 0); (1.3.3) ;(z ) = ;(;k + ) = (;k1) ! where 0 (1.3.4) (z ) = ;;((zz))
is the psi function. Then, since the poles bjl are simple, we have h i m;n (s)z ;s = h z ;b (j = 1; ; m; l = 0; 1; 2; ); Res H p;q jl s=b
(1.3.5)
jl
jl
where
h
hjl = slim (s ; bjl )Hm;n p;q (s) !b
i
jl
m Y
= (l;! 1)
l
; bi ; [bj + l] i j i=1
i6=j p Y
; ai ; [bj + l] i j i=n+1 Thus we obtain the result: j
! n Y !
; 1 ; ai + [bj + l] i j i=1 q Y
!
; 1 ; bi + [bj + l] i j i=m+1
!:
(1.3.6)
Theorem 1.3. Let the conditions in (1:1:6) and (1:3:1) be satis ed and let either > 0; z 6= 0 or = 0; 0 < jz j < . Then the H -function (1:1:1) has the power series expansion m;n (z ) = Hp;q
m X 1 X hjl z (bj +l)= j ; j =1 l=0
(1.3.7)
where the constants hjl are given in (1.3.6).
Similarly we consider the case (1.3.2) and from Theorem 1.2(ii) come to the statement:
Theorem 1.4. Let the conditions in (1:1:6) and (1:3:2) be satis ed and let either
< 0; z 6= 0 or = 0; jz j > . Then the H -function (1:1:1) has the power series expansion m;n (z ) = Hp;q
1 n X X
i=1 k=0
hik z(a ;1;k)= ; i
i
(1.3.8)
where the constants hik have the forms h i hik = s!lima ;(s ; aik )Hm;n p;q (s) ik
m Y
= (k;!1)
k
i
Y n ; bj + [1 ; ai + k] j ; 1 ; aj ; [1 ; ai + k] j i j =1 i j =1
j 6=i Y j q
; 1 ; bj ; [1 ; ai + k] j ; aj + [1 ; ai + k] i j =m+1 i j =n+1
p Y
(1.3.9)
7
1.4. Explicit Power-Logarithmic Series Expansions
in view of the relation ;s ;a (a ;1;k )= i [Hm;n : p;q (s)z ] = hik z ik = hik z i sRes =aik
(1.3.10)
1.4. Explicit Power-Logarithmic Series Expansions
When the conditions in (1.1.6) are satis ed, but some poles bjl in (1.1.4) or aik in (1.1.5) m;n (z ) by using Theorem 1.2 in cases coincide, we can also prove series representations for Hp;q (i) and (ii). First we consider the case (i). Let b bjl be one of the points (1.1.4) for which some other poles of the gamma functions ;(bj + j s) (j = 1; ; m) coincide and let N Njl be its overlapping order. This means that there exist j1 ; ; jN 2 f1; ; mg and lj1 ; ; ljN 2 f0; 1; 2; g such that (1.4.1) b bjl = ; bj1 + lj1 = = ; bjN + ljN : j1 jN ;s Thus Hm;n p;q (s)z has a pole at b of order N and hence h i 1 lim h(s ; b)N Hm;n (s)z ;s i(N ;1) : m;n (s)z ;s = (1.4.2) Res H p;q p;q s=b (N ; 1)! s!b Denoting jN Hm;n p;q (s) (1.4.3) H1(s) = (s ; b)N Y ;(bj + j s); H2(s) = jY N j =j1 ;(bj + j s) j =j1
and using the Leibniz rule, we have h
i(N ;1)
;s (s ; b)N Hm;n p;q (s)z
= =
;1 NX
n=0 ;1 NX
!
N ; 1 [H(s)](N ;1;n) H (s)z;s (n) 1 2 n !
!
n n N ; 1 [H(s)](N ;1;n) X (;1)i [H2 (s)](n;i) z ;s [log z ]i 1 n i i=0
n=0 ;1 (N ;1 NX X ; s (;1)i =z i=0 n=i
!
!
)
N ; 1 n [H (s)](N ;1;n) [H(s)](n;i) [log z]i: 2 n i 1 Substituting this into (1.4.2), we obtain Res s=b
h
jl
where
;s Hm;n p;q (s)z
i
= z (bj +l)= j
Njl ;1 X
i=0
[log z ]i ; Hjli
(1.4.4)
H (N ; bjl) Hjli jli jl
1
= (N ; 1)! jl
Njl ;1 X
n=i
(;1)i
!
!
Njl ; 1 n [H(b )](Njl ;1;n) [H (b )](n;i) : (1.4.5) 2 jl i 1 jl n
8
Chapter 1. De nition; Representations and Expansions of the H -function
In particular, if we pick the case l = 0 and i = Nj0 ; 1 which will be treated later (cf. Theorem 1.12), we have from (1.3.3) and (1.4.3) by setting Nj Nj0 1)Nj ;1 H (b )H (b ) Hj Hj; 0;Nj;1 (Nj; bj 0) = ((; Nj ; 1)! 1 j 0 2 j 0 m Y
=
; bi ; bj i j
!
n Y
; 1 ; ai + bj i j i=1
8 9 i=1 ;1 < Nj N = i6=j1 ;;jN j k Y j (;1) (;1) j ! q p Y (Nj ; 1)! :k=1 jk ! jk ; Y i ; ; ai ; bj j i=m+1 i=n+1
1 ; bi + bj i j
!
!
: (1.4.6)
Thus in view of Theorem 1.2(i), we obtain:
Theorem 1.5. Let the conditions in (1:1:6) be satis ed and let either > 0; z 6= 0 or = 0; 0 < jz j < . Then the H -function (1:1:1) has the power-logarithmic series expansion m;n (z ) = Hp;q
X0
j;l
hjlz (bj +l)= j +
N ;1
jl X00 X
i=0
j;l
z (bj +l)= j [log z ]i : Hjli
(1.4.7)
Here P0 and P00 are summations taken over j; l (j = 1; ; m; l = 0; 1; ) such that the gamma functions ;(bj + j s) have simple poles and poles of order Njl at the points bjl ; are given by respectively; and the constants hjl are given in (1:3:6) while the constants Hjli (1.4.5). Similarly we consider the case (ii) in Theorem 1.2. Let a = aik be one of the points (1.1.5) for which some other poles of ;(1 ; ai ; i s) coincide and let N = Nik be its overlapping order. This means that there exist i1; ; iN 2 f1; ; ng and ki1 ; ; kiN 2 N0 f0; 1; 2; g such that (1.4.8) a aik = 1 ; a i1 + ki1 = = 1 ; a iN + kiN : Then
i1 iN m;n ; s the integrand Hp;q (s)z in (1.1.1) has a pole at a of order N . Denoting iN Hm;n p;q (s) ; H1(s) = (s ; a)N Y ;(1 ; ai ; i s); H2(s) = Y iN i=i1 ;(1 ; ai ; i s) i=i1
similarly to the previous case we obtain h
;s Hm;n p;q (s)z sRes =aik
i
=z
ai ;1;k)= i
(
where Hikj Hikj (Nik; aik ) 1
8
= (N ; 1)! : ik n=j
!
!
NX ik ;1 j =0
(1.4.9)
Hikj [log z ]j ;
(1.4.10)
9
= (;1)j Nikn; 1 nj [H1 (aik )](Nik ;1;n) [H2(aik )](n;j ) ; : (1.4.11)
9
1.5. Algebraic Asymptotic Expansions at In nity
For the special choice of k = 0 and j = Ni0 ; 1; (1.4.9) and (1.3.3) yield, by setting Ni Ni0, Ni ;1 Hi Hi;0;Ni;1 (Ni; ai0) = ((;N1); 1)! H1(ai0)H2(ai0) i
0
1
Ni (;1)ik ;1 1)Ni ;1 @ Y A = ((; Ni ; 1)! k=1 ik ! ik
Y n j j ; 1 ; aj ; [1 ; ai ] ; bj + [1 ; ai ] i i j =1 j =1 m Y
Yp
j =n+1
;
j 6=i1 ;;iNi Yq ; j j ; 1 ; bj ; [1 ; ai ] aj + [1 ; ai] i j =m+1 i
(1.4.12)
which will appear in Theorem 1.8, below. Therefore Theorem 1.2(ii) implies: Theorem 1.6. Let the conditions in (1:1:6) be satis ed and let either < 0; z 6= 0 or = 0; jz j > . Then the H -function (1:1:1) has the power-logarithmic series expansion m;n (z ) = Hp;q
X0 i;k
hik z(ai;1;k)= i +
ik ;1 X00 NX
i;k
j =0
Hikj z(ai;1;k)= i [log z]j :
(1.4.13)
Here P0 and P00 are summations taken over i; k (i = 1; ; n; k = 0; 1; ) such that the gamma functions ;(1 ; ai ; i s) have simple poles and poles of order Nik at the points aik ; respectively, and the constants hik are given in (1:3:9) while the constants Hikj are given by (1.4.11).
1.5. Algebraic Asymptotic Expansions at In nity
When 5 0; the results in Theorems 1.4 and 1.6 give the power and power-logarithmic asymptotic expansions of the H -function near in nity, namely m;n (z ) Hp;q
n X 1 X
i=1 k=0
hik z(ai;1;k)= i (z ! 1);
(1.5.1)
when the poles aik in (1.4.8) of the gamma functions ;(1 ; ai ; i s) (1 5 i 5 n) do not coincide, and m;n (z ) Hp;q
X0 i;k
hik z(ai;1;k)= i +
ik ;1 X00 NX
i;k
j =0
Hikj z(ai;1;k)= i [log z]j (z ! 1);
(1.5.2)
when some poles aik coincide, where the summations in P0 and P00 are taken over i; k (i = 1; ; n; k = 0; 1; 2; ) as in Theorem 1.6 and Nik is the orders of the poles. If > 0; a > 0 and the conditions in (1.1.6) hold, then L = L;1 and the asymptotic expansion of the H -function at in nity has the form m;n (z ) Hp;q
1 n X X
i=1 k=0
s Res [Hm;n p;q (;s)z ] = s=;a ik
1 n X X
i=1 k=0
m;n ;s sRes =aik [Hp;q (s)z ]
a z ! 1; jarg zj < 2 :
(1.5.3)
10
Chapter 1. De nition; Representations and Expansions of the H -function
This result was proved by Braaksma [1, (2.16)]. He considered the H -function in the form Z 1 m;n (;s)z s ds m;n H (1.5.4) Hp;q (z) = 2i p;q L+1 and developed the method to nd the asymptotic expansion of this integral in the cases > 0 and = 0; 0 < jz j < : This method is based on the Cauchy theorem and the residue theory, according to which the contour L = L+1 is replaced by two other paths L1 and L2 , being contours surrounding L, and the integral (1.5.4) can be represented in the form Z Z m;n (;s)z s ds ; 1 m;n s m;n (z ) = Qw (z ) + 1 H (1.5.5) Hp;q 2i L1 p;q 2i L2 Hp;q (;s)z ds; s where Qw (z ) is the sum of residues of the function Hm;n p;q (;s)z at some points aik given in (1.1.5). When a > 0, two paths of integration in (1.5.5) may be replaced by the line parallel to the imaginary axis: Z w;i1 m;n s m;n (z ) = Q (z ) + 1 (1.5.6) Hp;q w 2i w+i1 Hp;q (;s)z ds; m;n (z ) can be where w is a certain real constant. It follows from here that, if = 0, Hp;q analytically continued into the sector (1.5.7) j arg(z)j < a2 ; and if > 0, the estimate m;n (z ) = Q (z ) + O(z w ) Hp;q (1.5.8) w and hence (1.5.3) holds for jz j ! 1 uniformly on every closed sector of (1.5.7). It follows from (1.5.3) that the H -function (with > 0; a > 0) also has the asymptotic expansions (1.5.1) and (1.5.2) in the cases when the poles aik of the gamma functions ;(1 ; ai ; i s) (1 5 i 5 n; k = 0; 1; 2; ) do not coincide and coincide, respectively. By the Cauchy theorem the results above are also valid for the H -function with L = Li 1 and a > 0 in the sector jarg z j < a =2.
Theorem 1.7. Let the conditions in (1:1:6) and (1:3:2) be satis ed and let either 5 0
m;n (z ) near in nity is given in (1:5:1) or > 0; a > 0. Then the asymptotic expansion of Hp;q and the principal terms of this asymptotic have the form m;n (z ) = Hp;q
n h i X hi z(ai;1)= i + o z(ai;1)= i (z ! 1);
(1.5.9)
i=1
where jarg z j < a =2 for > 0; a > 0 and Y m n Y ; bj ; (ai ; 1) j ; 1 ; aj + (ai ; 1) j i j =1 i j =1 1 j 6=i hi hi0 = Y : p Yq i j j ; 1 ; bj + (ai ; 1) ; aj ; (ai ; 1) j =n+1
i j =m+1
i
(1.5.10)
1.5. Algebraic Asymptotic Expansions at In nity
11
Corollary 1.7.1. Let the assumptions of Theorem 1:7 be satis ed and let i0 (1 5 i0 5 n)
be an integer such that
Re(ai0 ) ; 1 = max Re(ai ) ; 1 : i0 i 15i5n Then there holds the asymptotic estimate
m;n (z ) = h z (ai0 ;1)= i0 + o z (ai0 ;1)= i0 Hp;q (z ! 1); i0
(1.5.11) (1.5.12)
where jarg z j < a =2 for > 0; a > 0; and hi0 is given in (1:5:10) with i = i0 . In particular, m;n (z ) = O (z ) (z ! 1); Hp;q
(1.5.13)
where = max [fRe(ai ) ; 1g= i] and jarg z j < a =2 when > 0; a > 0. 15i5n
Theorem 1.8. Let the conditions in (1:1:6) be satis ed and let either 5 0 or > 0; a > 0. Let some poles of the gamma functions ;(1 ; ai ; is) (i = 1; ; n) coincide and m;n (z ) near in nity is Nik be the orders of these poles. Then the asymptotic expansion of Hp;q given in (1:5:2) and the principal terms of this asymptotic have the form m;n (z ) = Hp;q
X0 h (ai;1)= i (ai;1)= i i hiz +o z i
i X h + 00 Hi z (ai ;1)= i [log z ]Ni ;1 + o z (ai ;1)= i [log z ]Ni ;1 (z ! 1); (1.5.14) i a=2
where jarg z j < for > 0; a > 0. Here P0 and P00 are summations taken over i (i = 1; ; n) such that the gamma functions ;(1 ; ai ; i s) have simple poles and poles of order Ni Ni0 at the points ai0 ; respectively; and hi are given in (1:5:10) while Hi are given by (1.4.12).
Corollary 1.8.1. Let the assumptions of Theorem 1:8 be satis ed and let i01 and
i02 (1 5 i01; i02 5 n) be numbers such that Re(ai) ; 1 ; (1.5.15) 1 Re(a i01 ) ; 1 = 1max i 5i5n i01 when the poles aik (i = 1; ; n; k = 0; 1; ) are simple; and Re(a ) ; 1 i ; (1.5.16) 2 Re(a i02 ) ; 1 = 1max 5 i 5 n i02 i when the poles aik (i = 1; ; n; k = 0; 1; ) coincide. a) If 1 > 2; then the rst term in the asymptotic expansion of the H -function has the form
m;n (z ) = h z (ai01 ;1)= i01 + o z (ai01 ;1)= i01 Hp;q (z ! 1); i01
(1.5.17)
where jarg z j < a =2 for > 0; a > 0; and hi01 is given in (1:5:10) with i = i01. In particular; the relation (1:5:13) holds.
12
Chapter 1. De nition; Representations and Expansions of the H -function
b) If 1 5 2 and and the gamma function ;(1 ; ai ; i s) has the pole ai02 of order Ni02 ;
then the principal term in the asymptotic expansion of the H -function has the form
m;n (z ) = H z (ai02 ;1)= i02 [log z ]Ni02 ;1 + o z (ai02 ;1)= i02 [log z ]Ni02 ;1 Hp;q (1.5.18) i02 (z ! 1); where jarg z j < a =2 for > 0; a > 0 and Hi02 is given in (1:4:12) with i = i02. In particular; if N is the largest order of general poles of the gamma functions ;(1 ; ai ; i s) (i = 1; ; n); then m;n (z ) = O z [log z ]N ;1 Hp;q (z ! 1); (1.5.19) where = max [fRe(ai ) ; 1g= i] and jarg z j < a =2 when > 0; a > 0. 15i5n When > 0 and a 5 0; the asymptotic behavior of the H -function with L = L;1 at in nity is more complicated. Such asymptotic expansions have exponential form and can be obtained from the results by Braaksma [1]. The case > 0; a = 0 will be considered in the next section. It should be noted that these asymptotic expansions have di erent forms in sectors of changing arg z and contain the special function E (z ) de ned in (1.6.3). Asymptotics of the same form are also obtained in the special case n = 0 presented in Section 1.7.
1.6. Exponential Asymptotic Expansions at In nity in the Case > 0; a = 0 In the previous section we proved the asymptotic behavior of the H -function at in nity when 5 0 or > 0; a > 0. Now we consider the remaining case > 0; a = 0. Let
20 p 1 3 m X X c0 = (2i)m+n;p exp 4@ ai ; bj A i5 ; i=n+1 j =1 2 0 p 1 3 m X X d0 = (;2i)m+n;p exp 4; @ ai ; bj A i5 ; i=n+1 j =1 2 3 1 !(;j +1=2)= !1= X 1 5: Aj z exp 4 z E (z) = 2i j =0
(1.6.1) (1.6.2) (1.6.3)
Here the constants Aj (j 2 N0 ) depending on p; q; ai ; i (i = 1; ; p) and bj ; j (j = 1; ; q ) are de ned by the relations
Yp
i=1 Yq j =1
;(1 ; ai ; i s) ;(1 ; bj ; j s) =
NX ;1
!s
Aj N (s) + ;(;s +rN ; ;( ; s + j ; + 1 = 2) ; + 1 = 2) j =0
(1.6.4)
13
1.6. Exponential Asymptotic Expansions at In nity in the Case > 0; a = 0
where the function rN (s) is analytic in its domain of de nition and rN (s) = O(1) as jsj ! 1 uniformly on jarg sj 5 ; 1 (0 < 1 < ). In particular,
A0 = (2)(p;q+1)=2;
p q Y Y ;i ai +1=2 jbj ;1=2 : i=1 j =1
(1.6.5)
Theorem 1.9. Let a; ; and be given in (1:1:7){(1:1:10) and let the conditions in
(1:1:6) and (1:3:2) be satis ed. Let > 0; a = 0 and be a constant such that min [ i ; j ]: 0 < < 2 n+15i5p;15j 5m
(1.6.6)
Then there hold the following assertions. (i) The H -function (1:1:1) has the asymptotic expansion m;n (z ) Hp;q
n X 1 X i=1 k=0
hik z (a ;1;k)= + c0E zei=2 ; d0E ze;i=2 i
i
(1.6.7)
(z ! 1)
uniformly on jarg z j 5 . Here the constants hik (1 5 i 5 n; k = 0; 1; 2; ); c0 and d0 are given in (1:3:9); (1:6:1) and (1:6:2) and the series E (z ) has the form (1:6:3) with coecients Aj being de ned by (1:6:4): (ii) The main terms of (1:6:8) are expressed in the form m;n (z ) = Hp;q
n h X i=1
i hiz(a ;1)= + o z(a ;1)= i
i
i
h
i
i
h
i
+Az (+1=2)= c0 exp (B + Cz 1= )i ; d0 exp ;(B + Cz 1= )i
+O z (;1=2)= (z ! 1; jarg z j 5 );
(1.6.8)
where hi (i = 1; ; n) are given in (1:5:10) and !(+1=2)= !1= (2 + 1) A 0 ; B= A = 2i 4 ; C=
(1.6.9)
with A0 being given in (1.6.5). Proof. To prove (1.6.8) we apply the results by Braaksma [1]. First we note that if a = 0, then by (1.1.13) (1.6.10) a1 = ;a2 = 2 : Owing to (1.1.7), (1.1.8) and (1.1.11) the formulas (1.8), (1.10) and (2.12) in Braaksma [1] take the forms (1.6.11) = > 0; = 1 ; 0 = a1 ;
14
Chapter 1. De nition; Representations and Expansions of the H -function
and hence by (1.6.10)
0 = 2 :
(1.6.12)
The relations (4.1), (4.2) and (4.4) in Braaksma [1] for the function h1 (s) de ned by p Y n+1 h1(s) = m+n;p i=Y m j =1
sin[ (ai ; i s)]
sin[ (bj ; j s)]
(1.6.13)
have the forms
p h m X 1 1 iY Y X i s 0 h1(s) = c0e 1 ; e2i( j s;aj ) e2ki( j s;bj ) = cj ei j s j =n+1 j =1 k=0 j =0
and
p h m X 1 iY Y ; i s 0 h1(s) = d0e 1 ; e;2i( j s;aj ) e;2ki( j s;bj ) j =n+1 j =1 k=0 1 X = dj e;i j s ; j =0
(1.6.14)
(1.6.15)
where c0 and d0 are given in (1.6.1) and (1.6.2) and (1.6.16)
0 = 0 = 2 : Following De nition I of Braaksma [1] we denote by fm g (m = 0; 1; 2; ) the monotonic sequence which arises if we write down the set of numbers i and ; j (i; j = 0; 1; 2; ); in (1.6.14) and (1.6.15), respectively. It follows from (1.6.14) and (1.6.15) that (1.6.17) ;1 = ;0 = ; 2 ; 1 = 0 + 2 min [ i; j ]; ;2 = ;1 ; (1.6.18) n+15i5p;15j 5m
and thus
0 ; ;1 =
(1.6.19)
and
1 ; 0 = ;1 ; ;2 = 2
min
[ i ; j ]:
n+15i5p;15j 5m
(1.6.20)
Following Braaksma [1, p.265], for an arbitrary integer r we distinguish three di erent cases for r : a) there exists a non-negative integer i = i0 such that r = i0 ; while r 6= ; j for j = 0; 1; 2; ;
15
1.6. Exponential Asymptotic Expansions at In nity in the Case > 0; a = 0
b) there exists a non-negative integer j = j0 such that r = ; j0 ; while r 6= i for i = 0; 1; 2; ; c) there exist two non-negative integers i = i0 and j = j0 such that r = i0 = ; j0 . We de ne numbers Cr and Dr by Cr = ci0 , Dr = 0 in case a), Cr = 0, Dr = ;dj0 in case b), and Cr = ci0 , Dr = ;dj0 in case c). We also de ne the integer by the relation
= ; 0 = ;0
(1.6.21)
and note that = ; 1, = ;1 for 0 > 0, Cr = 0 if r < 0; and Dr = 0 if r > (see Braaksma [1, Lemma 4a]). Using these facts, the numbers Ci (i = 0; 1; 2; ) and Dj (j = ; ; 1; ) are de ned by
h1(s) =
1 X i=0
Ciei s ;
h1(s) = ;
i
X j =;1
Dj ei s:
(1.6.22)
j
By Braaksma [1, Theorem 7], if the conditions in (1.1.6) and (1.3.2) are satis ed, if > 0 and r ; r;1 = for some integer r; and if (1.6.23) 0 < < 41 min[r;1 ; r;2 ; r+1 ; r ]; then m;n (z ) ; Hp;q
n X 1 X i=1 l=0 rX ;1
;
j =0
sRes =a
il
h
;s Hm;n p;q (s)z
i
+
X j =r
Dj P zei
j
Cj P zei + (Cr + Dr )E zei + (Cr;1 + Dr;1)E zei ;1 (1.6.24) j
r
r
as jz j ! 1 uniformly on 1 ; 5 arg z + 5 1 + ; (1.6.25) r 2 2 where an empty sum is understood to be zero. Here P (z ) is de ned via a sum of residues p X 1 X
;s P (z ) = sRes = aik [h0(s)z ]; i=1 k=0
p Y
h0(s) =
i=1 q Y j =1
;(1 ; ai ; i s) ;(1 ; bj ; j s)
(1.6.26)
at points aik in (1.1.5) and E (z ) is given in (1.6.3). Now we apply Braaksma's theorem above to prove (1.6.8). If a = 0 and > 0, then in accordance with (1.6.19) and (1.6.11) we can take r = 0, by (1.6.20) the condition in (1.6.23) coincides with that in (1.6.6). Therefore the relation (1.6.24) holds for jz j ! 1 uniformly on the domain in (1.6.25) which gives j arg z j 5 if we take into account that (1.6.27) 0 = 2 > 0
16
Chapter 1. De nition; Representations and Expansions of the H -function
according to (1.6.16) and (1.6.11). The evaluation of the residues in the double sum in (1.6.24), similarly to those in Theorem 1.4, gives the double sum in (1.6.8). By virtue of (1.6.27) (and (1.6.21)), = ;1 and so the second and the third sums in (1.6.24) vanish. So (1.6.24) is reduced to the form m;n (z ) Hp;q
n X 1 X i=1 k=0
hik z(a ;1;k)= + (C0 + D0 )E zei0 + (C;1 + D;1)E zei;1 ; i
i
(1.6.28)
where hik are given in (1.3.9). To evaluate C0, D0 , C;1 and D;1 , we note that by (1.6.16) there exists i0 = 0 such that 0 = 0, and it follows from (1.6.14) and (1.6.15) that 0 6= ; j for j = 0; 1; 2; ; if we take into account (1.6.27). So, the case a) above is realized and C0 = Cr = ci0 = c0 while D0 = Dr = 0; where c0 is given in (1.6.1). Further, since Cr = 0 if r < 0 (for 0 > 0) C;1 = 0; and in view of (1.6.15) and the second relation in (1.6.22), we have D;1 = ;d0, where d0 is given in (1.6.2). Substituting these values of C0, D0 , C;1 and D;1 into (1.6.28), we obtain (1.6.8). This completes the proof of the rst assertion (i) of Theorem 1.9. The second one (ii) follows from (1.6.8), if we take into account (1.6.1){(1.6.3) and (1.6.5).
Corollary 1.9.1. Let the assumptions of Theorem 1:9 hold and i0 (1 5 i0 5 n) be such
number that (1:5:11) is satis ed. Then the H -function (1:1:1) has the form (i) If [Re(ai0 ) ; 1]= i0 > Re( + 1=2)=;
m;n (z ) = h z (a 0 ;1)= 0 + o z (a 0 ;1)= 0 Hp;q (z ! 1); i0 where hi0 is given in (1:5:10) with i = i0. (ii) If [Re(ai0 ) ; 1]= i0 < Re( + 1=2)=; h i h i m;n (z ) = Az (+1=2)= c exp (B + Cz 1=)i ; d exp ;(B + Cz 1=)i Hp;q 0 0 i
i
i
i
+o z (+1=2)= (z ! 1; jarg z j 5 );
where A; B and C are given in (1:6:9): (iii) If [Re(ai0 ) ; 1]= i0 = Re( + 1=2)=; m;n (z ) = hi z (+1=2)= Hp;q 0
h
i
(1.6.29)
(1.6.30)
h
+Az (+1=2)= c0 exp (B + Cz 1= )i ; d0 exp ;(B + Cz 1= )i
+o z (+1=2)= (z ! 1; jarg z j 5 ):
i
(1.6.31)
In particular; where
m;n (z ) = O (z ) (z ! 1; jarg z j 5 ); Hp;q
(1.6.32)
= max Re(a i) ; 1 ; Re()+ 1=2 : 15j 5m i
(1.6.33)
17
1.7. Exponential Asymptotic Expansions at In nity in the Case n = 0
Remark 1.3. If the poles aik in (1.1.5) of the gamma functions ;(1 ; ai ; is) (i =
1; ; n) are not simple (i.e. the conditions in (1.3.2) are not satis ed), then similarly to the results in Section 1.5 it can be proved that the logarithmic multipliers of the form [log z ]N ;1 may be added in the asymptotic expansions (1.6.8), (1.6.8), (1.6.29){(1.6.32).
1.7. Exponential Asymptotic Expansions at In nity in the Case n = 0 In this section we give the asymptotic behavior of the H -function in the special case n = 0 provided that > 0; a > 0. Let c0; d0 and A0 be given in (1.6.1){(1.6.2) and (1.6.5). We note that, in particular, when n = 0 and q = m; c0 and d0 take the forms
c0 = (2 )q;pe;i ; d0 = (2 )q;pei ;
(1.7.1)
where is given in (1.1.10). Let
ia1 !(+1=2)= ia1 !1= e e c A 0 0 ; 1 = 2 ; D1 = ; C1 = 2i
;ia1 !(+1=2)= ;ia1 !1= e e d A 0 0 ; 1 = 2 ; D2 = : C2 = 2i The following statement holds.
(1.7.2) (1.7.3)
Theorem 1.10. Let n = 0; a; ; ; and a1 be given in (1:1:7){(1:1:10) and (1:1:11)
and let the conditions in (1:1:6) and (1:3:2) be satis ed. Let > 0; a = 0 and let be a constant such that (1.7.4) 0 < < 2 : Then there hold the following assertions. q;0(z ) has the asymptotic expansions at (i) If m = q and a > 0; then the H -function Hp;q in nity
q;0(z ) c E zeia1 Hp;q 0
and
(z ! 1)
q;0(z ) ;d0 E z ;ia1 Hp;q (z ! 1)
(1.7.5) (1.7.6)
uniformly on jarg z j 5 =2 ; ; where c0 and d0 are given in (1:7:1) and E (z ) in (1:6:3): The principal terms in these asymptotics have the forms " 1= # 1 = (+1=2)= q; 0 D z (z ! 1) (1.7.7) Hp;q (z) = C1e 1 z 1 + O z1 and " 1=# 1= (+1=2)= q; 0 D z 2 (z ! 1); (1.7.8) Hp;q (z ) = ;C2e z 1 + O z1
18
Chapter 1. De nition; Representations and Expansions of the H -function
respectively. m;0 (z ) has the asymptotic expansion (ii) If m < q and a = 0; then the H -function Hp;q
m;0 (z ) c E zeia1 ; d E ze;ia1 Hp;q 0 0
(z ! 1)
(1.7.9)
uniformly on jarg z j 5 with 0 < < a=4 for a > 0 and 0 < < 2 min [ i ; j ] 15i5p;15j 5m for a = 0; where c0 and d0 are given in (1:6:1) and (1:6:2) with n = 0. The main term in this representation has the form m;0(z ) = Hp;q
h
C1eD1z1= ; C2eD2z1=
i
" 1=# ( +1 = 2) = (z ! 1): z 1+O 1
z
(1.7.10)
Proof. When m = q; a > 0 and m < q; a > 0, the results in (1.7.5), (1.7.6) and (1.7.9)
follow from those proved by Braaksma [1; Theorem 4, the relations (7.11), (7.12) and (7.15)] (see Section 1.11), if we take into account the formulas in (1.6.11) and the equality (1.7.11) 0 ; 12 = 21 a ; which is valid due to (1.6.11) and (1.1.13). When m < q and a = 0, by (1.6.10) the asymptoic estimate (1.7.9) follows from the relation (1.6.8) in Theorem 1.9 in the case n = 0. According to (1.7.1){(1.7.3) the relations (1.7.7) and (1.7.8) are deduced from (1.7.5) and (1.7.6) while (1.7.10) is obtained from (1.7.9).
Corollary 1.10.1. If the assumptions of Theorem 1:10 are satis ed; then for the
m;0(z ); the following asymptotic estimate holds at in nity: H -function Hp;q m;0(z ) = O jz j[Re()+1=2]= Hp;q (
)!
1= max cos (a1 +arg z ) ; cos (a1 ;arg z ) (z ! 1)(1.7.12) exp jz j uniformly on jarg z j 5 (=2) ; and on jarg z j 5 when m = q and m < q; respectively.
Corollary 1.10.2. If the assumptions of Theorem 1:10 are satis ed, then for the m;0(x) with real x the following asymptotic estimates hold at in nity: H -function Hp;q m;0(x) = O x[Re()+1=2]= exp cos a1 ;1= x1= (x ! +1): (1.7.13) Hp;q In particular, h i q;0(x) = O x[Re()+1=2]= exp ; ;1= x1= Hp;q (x ! +1):
(1.7.14)
19
1.8. Algebraic Asymptotic Expansions at Zero
m; (z ) is more Remark 1.4. The asymptotic estimate (1.7.13) for the H -function Hp;q 0
precise than those given by Mathai and R.K. Saxena [2, (1.6.3)] and Srivastava, Gupta and Goyal [1, (2.2.14)].
1.8. Algebraic Asymptotic Expansions at Zero
When = 0 the results in Theorems 1.3 and 1.5 lead us to the power and power-logarithmic asymptotic expansions of the H -function near zero, namely, m;n (z ) Hp;q
m X 1 X hjlz(bj +l)= j j =1 l=0
(z ! 0);
(1.8.1)
when any pole bjl of the gamma functions ;(bj + j s) (1 5 j 5 m) do not coincide, and Njl ;1 X0 (b +l)= X00 X m;n z (bj +l)= j [log z ]i Hp;q (z) hjlz j j + Hjli j;l j;l i=0
(z ! 0);
(1.8.2)
when some of the poles bjl of the gamma functions ;(bj + j s) (1 5 j 5 m) coincide. Here the summation signs P0 and P00 are taken as in Theorem 1.5. On the other hand if < 0; a > 0 and the conditions in (1.1.6) hold, then for L = L+1 similar arguments to those in Section 1.5 lead us to the following asymptotic expansion of the H -function at zero: m 1 a m;n (z ) ; X X Res [Hm;n (;s)z s ] (1.8.3) Hp;q z ! 0 ; j arg z j < p;q 2 j =1 l=0 s=;b jl
with a being de ned in (1.1.7). It follows from here that the H -function (1.1.1) also has the asymptotic expansions (1.8.1) and (1.8.2) in the respective cases when the poles bjl of the gamma functions ;(bj + j s) (1 5 j 5 m) do not coincide and coincide. By Cauchy's theorem the results above are also valid for the H -function (1.1.1) with L = Li 1 and a > 0. Thus we have:
Theorem 1.11. Let the conditions in (1:1:6) and (1:3:1) be satis ed and let either = 0 m;n (z ) near zero is given in (1:8:1) or < 0; a > 0. Then the asymptotic expansion of Hp;q with the additional condition j arg z j < a =2 when < 0; a > 0. The principal terms of this asymptotic have the form m;n (z ) = Hp;q
where
m h X hj z bj = j j =1
m Y
hj hj 0 = 1
; bi ; bj i j i=1
i6=j p Y j
; ai ; bj i j i=n+1
! n Y !
+ o z b = j
j
i
(z ! 0);
; 1 ; ai + bj i j i=1 q Y
(1.8.4)
!
; 1 ; bi + bj i j i=m+1
!
(j = 1; ; m):
(1.8.5)
20
Chapter 1. De nition; Representations and Expansions of the H -function
Corollary 1.11.1. Let the assumptions of Theorem 1:11 be satis ed and let j (1 5 j 5 m) 0
be an integer such that
"
0
#
Re(bj0 ) = min Re(bj ) : j0 j 15j 5m Then there holds the asymptotic estimate
m;n (z ) = h z b 0 = 0 + o z b 0 = 0 Hp;q j0 j
j
j
j
(1.8.6) (z ! 0);
(1.8.7)
where j arg z j < a=2 when < 0; a > 0; and hj0 is given in (1:8:5) with j = j0. In particular;
m;n (z ) = O z Hp;q
(z ! 0);
(1.8.8)
where = min [Re(bj )= j ] and j arg z j < a =2 when < 0; a > 0. 5j 5 m
1
Theorem 1.12. Let the conditions in (1:1:6) be satis ed and let either = 0 or < 0; a > 0. Let some poles of the gamma functions ;(bj + j s) (j = 1; ; m) coincide m;n (z ) near zero and let Njl be the orders of these poles. Then the asymptotic expansion of Hp;q is given in (1:8:2) with the additional condition j arg z j < a =2 when < 0; a > 0. The principal terms of these asymptotics have the form
i X0 h b = hj z j j + o z bj = j j i X h + 00 Hj z bj = j [log z ]Nj ;1 + o z bj = j [log z ]Nj ;1 (z ! 0); (1.8.9) j a =2 when < 0; a > 0. Here P0 and P00 are summations taken over
m;n (z ) = Hp;q
where j arg z j < j (j = 1; ; m) such that the gamma functions ;(bj + j s) have simple poles and poles of order Nj Nj0 at the points bj 0 ; respectively, and hj are given in (1:8:5) while Hj are given by (1.4.6).
Corollary 1.12.1. Let the assumptions of Theorem 1:12 be satis ed and let j and j 01
(1 5 j01; j02 5 m) be numbers such that
1
"
#
Re(bj01 ) = min Re(bj ) ; j01 j 15j 5 m
02
(1.8.10)
when the poles bjl (j = 1; ; m; l = 0; 1; ) are simple; and
2
"
#
Re(bj02 ) = min Re(bj ) ; j02 j 15j 5 m
(1.8.11)
when the poles bjl (j = 1; ; m; l = 0; 1; ) coincide. a) If 1 < 2; then the principal term in the asymptotic expansion of the H -function has the form
m;n (z ) = h z b 01 = 01 + o z b 01 = 01 Hp;q j01 j
j
j
j
(z ! 0);
(1.8.12)
21
1.9. Exponential Asymptotic Expansions at Zero in the Case < 0; a = 0
where j arg z j < a =2 for < 0; a > 0 and hj01 is given in (1:8:5) with j = j01. In particular; the relation (1:8:8) holds with 1 instead of there. b) If 1 = 2 and the gamma function ;(bj + j s) has the pole bj02 of order Nj02 ; then the principal term in the asymptotic expansion of the H -function has the form m;n (z ) = H z bj02 = j02 [log z ]Nj02 ;1 + o z bj02 = j02 [log z ]Nj02 ;1 Hp;q (z ! 0); (1.8.13) j02 where j arg z j < a =2 for < 0; a > 0; and Hj02 is given in (1:4:6) with j = j02. In particular; if N is the largest order of general poles of gamma functions ;(bj + j s) (j = 1; ; m); then m;n (z ) = O z [log z ]N ;1 Hp;q (z ! 0); (1.8.14) where = min [Re(bj )= j ] and j arg z j < a =2 when < 0; a > 0. 15j 5m
When < 0 and a 5 0; the asymptotic behavior of the H -function (1.1.1) near zero is more complicated. For L = L+1 such asymptotic estimates have exponential forms and can be found by the method similar to nding asymptotics of the H -function with L = L;1 for > 0 at in nity which was suggested by Braaksma in [1]. The former asymptotic expansions can also be deduced from the latter ones on the basis of the translation formula " (a ; ) # " (1 ; b ; ) # j j 1;q i i 1;p m;n n;m ; (1.8.15) Hp;q z = Hq;p z1 (1 ; ai ; i)1;p (bj ; j )1;q if we take into account the relations (1.8.16) a0 = ;a; 0 = ;; 0 = 1 ; 0 = ; a10 = a2; a20 = a1: 1 n;m instead of a; ; ; ; a1 and a2 for Here we use a0; 0; 0 ; 0 ; a10 and a20 for Hq;p z m;n [z ] de ned by (1.1.7){(1.1.12). Hp;q The case < 0; a = 0 will be considered in the next section. It should be noted that the asymptotic expansions for the H -function (1.1.1) have di erent forms in sectors of changing arg z and contain the special function E (z ) de ned in (1.9.3) below. Asymptotics of the same form are also found in the special case m = 0 presented in Section 1.10.
1.9. Exponential Asymptotic Expansions at Zero in the Case < 0; a = 0
In the previous section we proved the asymptotic behavior of the H -function (1.1.1) when = 0 or < 0; a > 0. Now we consider the remaining case < 0; a = 0. Let
2 0 q 1 3 n X X c0 = (;2i)n+m;q exp 4; @ bj ; ai A i5 ; j =m+1 i=1 20 q 1 3 n X X d0 = (2i)n+m;q exp 4@ bj ; ai A i5 ; j =m+1 i=1 2 jj !1=jj3 1 jj !(;j +1=2)=jj X j j 1 4 jj 5: exp E (z) = 2i jj Aj z z j =0
(1.9.1) (1.9.2) (1.9.3)
22
Chapter 1. De nition; Representations and Expansions of the H -function
Here the constants Aj ; depending on p; q; ai; i; bj and j (i = 1; ; p; j = 1; ; q ); are de ned by the relations
Yq
j =1 Yp i=1
;(bj + j s) ;(ai + i s) =
jjjj
;s
NX ;1
Aj rN (s) + ; j =0 ;(s + j ; + 1=2) ;(s + N ; + 1=2)
(1.9.4)
where the function rN (s) is analytic in its domain and rN (s) = O(1) as jsj ! 1 uniformly on jarg sj 5 ; 1 (0 < 1 < ). In particular,
Yp ai;1=2 Yq ;bj +1=2 ; ( q ; p +1) = 2 A0 = (2) jj i j : i=1 j =1
(1.9.5)
Theorem 1.13. Let a; ; and be given in (1:1:7){(1:1:10) and let the conditions
in (1:1:6) and (1:3:1) be satis ed. Let < 0; a = 0 and be a constant such as min [ ; ]: 0 < < 2 15i5n;m+15j 5q i j Then there hold the following assertions: (i) The H -function (1:1:1) has the asymptotic expansion m;n (z ) Hp;q
m X 1 X
j =1 l=0
hjlz(bj +l)= j + c0E ze;i=2 ; d0E zei=2
(1.9.6)
(1.9.7)
(z ! 0)
uniformly on jarg z j 5 . Here the constants hjl (1 5 j 5 m; l = 0; 1; 2; ); c0 and d0 are given in (1:3:6); (1:9:1) and (1:9:2); and the series E (z ) has the form (1:9:3) with coecients Aj being de ned by (1:9:4): (ii) The main part of (1:9:8) is expressed in the form m;n (z ) = Hp;q
m h X
j =1
hj z bj = j + o z bj = j
i
h i h i +A z ;(+1=2)=jj c0 exp ;(B + C z ;1=jj )i ; d0 exp (B + C z ;1=jj )i +O z (;+1=2)=jj (z ! 0; jarg z j 5 );
where hj (j = 1; ; m) are given in (1:8:5) and (+1=2)=jj 1=jj ; B = (2 +4 1) ; C = jjjj A = 2iA0jj jjjj with A0 being given in (1.9.5).
(1.9.8) (1.9.9)
1.9. Exponential Asymptotic Expansions at Zero in the Case < 0; a = 0
23
Proof. The assertion (i) is deduced from Theorem 1.9(i) if we apply the translation for-
mula (1.8.15) and the relations in (1.8.16). According to the latter, the conditions of Theorem 1.13 coincide with those in Theorem 1.9 with rearrangement of m and n and p and q; and with replacement of a , and by ;a , ; and 1= . The assertion (ii) follows from (i) according to (1.9.1){(1.9.3) and (1.9.5).
Corollary 1.13.1. Let the assumptions of Theorem 1:13 hold and let j0 (1 5 j0 5 m)
be a number such that (1:8:6) is satis ed. Then the H -function has the form (i) If Re(bj0 )= j0 + Re( + 1=2)= jj < 0;
m;n (z ) = h z bj0 = j0 + o z bj0 = j0 Hp;q j0
(z ! 0);
(1.9.10)
where hj0 is given in (1:8:5) with j = j0 . (ii) If Re(bj0 )= j0 + Re( + 1=2)= jj > 0;
h i m;n (z ) = A z ;(+1=2)=jj c exp ;(B + C z ;1=jj )i Hp;q 0 h i ;d0 exp (B + C z;1=jj)i +o z ;(+1=2)=jj (z ! 0; jarg z j 5 );
(1.9.11)
where A ; B and C are given in (1:9:9): (iii) If Re(bj0 )= j0 + Re( + 1=2)= jj = 0; m;n (z ) = h z ;(+1=2)=jj Hp;q j0
h i +A z ;(+1=2)=jj c0 exp ;(B + C z ;1=jj )i
h i ;d0 exp (B + C z;1=jj )i +o z ;(+1=2)=jj (z ! 0; jarg z j 5 ): In particular;
m;n (z ) = O z Hp;q
where
=
"
(z ! 0; jarg z j 5 );
#
min Re( bj ) ; ; Re(j)+j 1=2 : 15j 5m j
(1.9.12) (1.9.13) (1.9.14)
Remark 1.5. If the poles bjl in (1.1.4) of the gamma functions ;(bj + j s) (j = 1; ; m) are not simple (i.e. the conditions in (1.3.1) are not satis ed), then similarly to the results in Section 1.8 it can be proved that the logarithmic multipliers of the form [log z ]N ;1 may be added in the asymptotic expansions (1.9.7), (1.9.8), (1.9.10){(1.9.13).
24
Chapter 1. De nition; Representations and Expansions of the H -function
1.10. Exponential Asymptotic Expansions at Zero in the Case m = 0 In this section we give the asymptotic behavior of the H -function in the special case m = 0 provided that < 0; a > 0. Let c0 ; d0 and A0 be given in (1.9.1), (1.9.2) and (1.9.5). We note that, in particular, when m = 0 and p = n; c0 and d0 take the forms
c0 = (2 )p;qe;i ; d0 = (2 )p;qei ; where is given in (1.1.10). Let (+1=2)=jj 1=jj A ;1=2 0 jj e;ia2 ; D1 = jj e;ia2 ; C1 = c20i
A0 jj;1=2 eia2 C2 = d20i
(+1=2)=jj
; D2 = jj eia2
1=jj
:
(1.10.1) (1.10.2) (1.10.3)
The following statement holds.
Theorem 1.14. Let m = 0; and let a; ; ; and a2 be given in (1:1:7){(1:1:10) and
(1:1:12). Let us assume the conditions in (1:1:6) and (1:3:1). If < 0; a = 0 and is a constant such that (1.10.4) 0 < < j2j ; then there hold the following assertions: 0;p(z ) has the asymptotic expansions at (i) If n = p and a > 0; then the H -function Hp;q zero
0;p(z ) cE zeia2 Hp;q 0
and
0;p(z ) ;d E ze;ia2 Hp;q 0
(jz j ! 0)
(1.10.5)
(z ! 0)
(1.10.6)
uniformly on jarg z j 5 jj =2 ; ; where c0 and d0 are given in (1:10:1) and E (z ) in (1:9:3). The principal terms in these asymptotics have the forms and
0;p(z ) = C eD1 z;1=jj z ;(+1=2)=jj h1 + O z 1=jj i (z ! 0) Hp;q 1
(1.10.7)
0;p(z ) = ;C eD2 z;1=j j z ;(+1=2)=jj h1 + O z 1=jj i (z ! 0); Hp;q 2
(1.10.8)
respectively. 0;n(z ) has the asymptotic expansion (ii) If n < p and a = 0; then the H -function Hp;q
0;n(z ) cE zeia2 ; dE ze;ia2 Hp;q 0 0
uniformly on jarg z j 5 with 0 < < a=4 for a > 0 and 0 < < 2 min [ i ; j ] 15i5n;15j 5q
(z ! 0)
(1.10.9)
25
1.11. Bibliographical Remarks and Additional Information on Chapter 1
for a = 0; where c0 and d0 are given in (1:9:1) and (1:9:2) with m = 0. The main term in this representation has the form 0;n(z ) = hC eD1 z;1=jj ; C eD2 z;1=jj i z ;(+1=2)=jj h1 + O z 1=jj i Hp;q 1 2 (z ! 0):
(1.10.10)
Proof. The assertions (i) and (ii) are deduced from Theorem 1.10 on the basis of the
translation formula (1.8.15) and of the relations in (1.8.16).
Corollary 1.14.1. If the assumptions of Theorem 1:14 are satis ed; then the H -function 0;n(z ) has the following asymptotic estimate at zero: Hp;q 0;n(z ) = O jz j;[Re()+1=2]=jj Hp;q (
)!
1=jj + arg z ) ; arg z ) ( a ( a 2 2 max cos exp jj jzj jj ; cos jj (z ! 0)
(1.10.11)
uniformly on jarg z j 5 jj =2 ; and on jarg z j 5 when n = p and n < p; respectively.
Corollary 1.14.2. If the assumptions of Theorem 1:14 are satis ed; then the H -function
0;n(x) for real x has the following asymptotic estimates at zero: Hp;q
0;n (x) = O x;[Re()+1=2]=jj exp cos a2 jj 1=jj x;1=jj Hp;q jj (x ! +0):
(1.10.12)
In particular;
0;p(x) = O x;[Re()+1=2]=jj exp h; jj 1=jj x;1=jj i (x ! +0): Hp;q
(1.10.13)
1.11. Bibliographical Remarks and Additional Information on Chapter 1 For Sections 1.1 and 1.2. The so-called Mellin{Barnes integral of the gamma functions were rst introduced by S. Pincherle [1] (1888), and the theory has been developed by Mellin [1] (1910), where references to earlier works were indicated in the book by Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 1.19]. Dixon and Ferrar [1] (1936) rst investigated the H-function represented by the Mellin{Barnes integral (1.1.1) with L = Li 1 . In the case m = n = 1 and p = q = 2 they proved the statements of Theorem 1.1 for L = Li 1 and of Theorem 1.2(iii), as well as the absolute convergence of the integral in (1.1.1) for any real z = x > 0 in the case a = = 0 and Re() < ;1; and of the convergence of H21;;21(z) for z = x > 0 (x 6= ) in the case a = = 0 and ;1 5 Re() < 0. They also studied analytic continuation of H21;;21(z) and indicated that these results can be extended to the m;n (z) of the form (1.1.1). One may refer these results to Section 1.19 of the book general integrals Hp;q by Erdelyi, Magnus, Oberhettinger and Tricomi [1].
26
Chapter 1. De nition; Representations and Expansions of the H -function
Interest in the H-function (1.1.1) returned in 1961 when Fox [2] investigated a particular case of such a function with L = Li 1 in the form " # (1 ; ai ; i)1;p ; (ai ; i ; i)1;p q;p q;p H2p;2q (x) H2p;2q x (x > 0) (1.11.1) (bj ; j )1;q ; (1 ; bj ; j ; j )1;q as a symmetrical Fourier kernel in L2(R+ ), which means that for H1 (x) = the transforms
Z
x
0
H2q;pp;2q (t)dt
(1.11.2)
d Z 1 H (xt)f(t) dt ; f(x) = d Z 1 H (xt)g(t) dt g(x) = dx 1 1 t dx t 0
0
hold for f; g 2 L2 (R+ ) provided that
q X
p X
j ; 2 i > 0; j =1 i=1 j i Re(ai ) > 2 ; Re(bj ) > ; 2 (1 5 i 5 p; 1 5 j 5 q): We also note that for such a function the constants in (1.1.7) and (1.1.9) take the forms =2
q
p
Y Y a = 0; = j2 j ;i 2 i : j =1 i=1
(1.11.3)
(1.11.4)
m;n (z) in (1.1.1) is sometimes called Fox's H-function. Therefore Hp;q Braaksma [1, Theorem 1] (1964) proved the existence of the H-function (1.1.1) with L = L;1 , its analyticity and representation (1.2.22), for the cases (1.2.14) and (1.2.15) (see also the books by Mathai and R.K. Saxena [2, Section 1.1] and Srivastava, Gupta and Goyal [1, Section 2.2]). We m;n (z) as an analytic function that is multiple-valued note that Braaksma probably rst considered Hp;q in general, but one-valued on the Riemann surface of log(z). He suggested some extensions of the de nition of the H-function by its analytic continuation and such extensions were also discussed by Skibinski [1] (1970). The proofs of Theorems 1.1 and 1.2, which were based on Lemmas 1.1 and 1.2 presenting di erent behaviors (1.2.11) and (1.2.12) of the integrand (1.1.2) at in nity, were given by the authors, see Kilbas and Saigo [6, Theorems 1 and 2]. We indicate that the representation (1.2.23) can also be deduced from (1.2.22) by using the translation formula (1.8.15), which was probably rst found by K.C. Gupta and U.C. Jain [1] (1966). It should be noted that the H-function makes sense under di erent conditions when either L = Li 1 , L = L;1 or L = L+1 , as shown in Theorem 1.1. This fact was rst noted by Prudnikov, Brychkov and Marichev [3, 8.3.1] (Russian edition in 1985). In this connection we notice that the remark in Mathai and R.K. Saxena [2, Section 1.1] is not correct, where it is mentioned that the existence of the H-function does not depend on the contour L. Prudnikov, Brychkov and Marichev [3, 8.3.1] also indicated that the parameter in the cases (1.2.16) and (1.2.19) of Theorem 1.1 can be extended from Re() < 0 to Re() < ;1. We also note that the notation for the H-function given in (1.1.1) was suggested by Gupta [2] (1965), while the notation of numbers in (1.1.7){(1.1.10) and (1.1.15) is by Prudnikov, Brychkov and Marichev [3, 8.3.1]. For Sections 1.3 and 1.4. The power series representation (1.3.7) was rst given by Braaksma [1, (6.5)]. The representations (1.3.7) as well as (1.3.8) were presented in the books by Mathai and R.K. Saxena [2, (3.7.1) and (3.7.2)], Srivastava, Gupta and Goyal [1, (2.2.4) and (2.2.7)] and Prudnikov, Brychkov and Marichev [3, 8.3.2(3) and 8.3.2(4)]. Their proofs were also given by the authors in Kilbas and Saigo [7, Theorems 3 and 4].
27
1.11. Bibliographical Remarks and Additional Information on Chapter 1
The power-logarithmic series representations (1.4.7) and (1.4.13) were obtained by the authors in the abovep;0paper [6, Theorems 5 and 6]. We also note that, in particular cases of the H-function of the p;0(z), the power-logarithmic series representations, which are more complicated forms H0;p (z) and Hp;p than in (1.4.7), were given by Mathai and R.K. Saxena [2, Section 3.7] (see also Mathai and R.K. Saxena [1, Section 5.8] and Mathai [1]). For Sections 1.5{1.7. Bochner [1, p.351] (1951) probably rst obtained the asymptotic estimate at a large positive z of the H-function with L = L;1 in the case p = 0 and m = q. Braaksma [1] developed the method to nd the asymptotic expansion of the general H-function with L = L;1 . Fox [2] investigated the asymptotic behavior at in nity of the H-function H2q;pp;2q(x) in (1.11.2) with L = Li 1 (0 < < 1=2), provided that > 0; q > p and ai (1 5 i 5 p) satisfy the conditions in (1.11.3) while Re(bj ) > 0 (1 5 j 5 q): His method was based on the representation of (1.11.1): ;s Z Z 1 1 q;p q;p ; s H2p;2q (s)x ds = 2i Q(s) x ds (1.11.5) H2p;2q (x) = 2i Li 1 Li 1 for = ; and the function Hq;p 2p;2q (s) being given in (1.1.2) and on the asymptotic estimate of Q(s) for large s, s = + it with xed by employing residue theory. He proved [2, Theorem 9] the following asymptotic estimates for a large positive x: " ;n= 1= # (1;)=2 X r x 1 ; x q;p cn sin 2 K ; n + 2 + x H2p;2q (x) = n=0
+
p X ui X i=1 j =0
; Aij x;(ai +j )= i + O x; 0 (x ! +1);
(1.11.6)
when q ; p is an odd positive integer, and " ;n= 1= # (1;)=2 r X x 1 ; x q;p cn cos 2 K ; n + 2 + x H2p;2q (x) = n=0 +
p X ui X i=1 j =0
; Cij x;(ai +j )= i + O x; 0 (x ! +1);
when q ; p is an even positive integer. Here 2
p X
j =1
i=1
K = 24
q X
(bj + j ) ;
(1.11.7)
3
ai5 ;
(1.11.8)
, and are given in (1.11.3), (1.11.4) and (1.11.5), 0 > 1=2 is a given constant, r denotes the greatest integer of [(2 0 ; 1) + 3]=2 and ui denotes the greatest positive integer of i 0 ; Re(ai ) (1 5 i 5 p), while cn (0 5 n 5 r) and Cij (1 5 i 5 p; 0 5 j 5 ui ) are constants which depend on ai , i (1 5 i 5 p) and bj , j (1 5 j 5 q) but are independent of x. The constants c0; c1 ; ; cr are de ned for large t, s = + it with xed , by r X (K ; s) 1 ; Q(s) ; cn; s ; n + 2 sin 2 n=0
= O jsj(;2r;1+2 ;)=r ; when q ; p is odd, and Q(s) ;
r X
cn ; s ; n + 1 ;2 cos (K ;2s) n=0
= O jsj(;2r;1+2 ;)=r ;
(1.11.9)
(1.11.10)
28
Chapter 1. De nition; Representations and Expansions of the H -function
when q ; p is even. The constants Cij (1 5 i 5 p; 0 5 j 5 ui) are obtained by using residue theory to compute the integrals of the form (1.11.5) in which Q(s) is replaced by the left-hand side of (1.11.9) and (1.11.10) for an odd and even q ; p, respectively. As was indicated in Section 1.5, Braaksma [1] (1964) developed the method, based on the Cauchy theorem and residue theory, to rewrite (1.5.4) in the form (1.5.5) and to nd the asymptotic expansion m;n (z) with L = L+1 in the cases > 0 and = 0; 0 < jz j < : When of the general H-function Hp;q > 0 and a > 0, he proved the asymptotic expansion (1.5.3) (see [1, (2.16)]), which is called an algebraic asymptotic expansion. In the general case, when > 0 but a is not necessary positive, Braaksma [1, Theorem 3] obtained m;n (z) in the form the algebraic asymptotic expansion for Hp;q m;n (z) Hp;q
n X 1 X
i=1 k=0
Res [Hm;n (s)z ;s ] + s=aik p;q
X j =r
;
Dj P zeij ;
r;1 X j =0
;
Cj P zeij ;
(1.11.11)
which holds for jz j ! 1 uniformly on ; + 5 arg(z) 5 ; ; ; (1.11.12) r r;1 2 2 1 0 < < 2 (r ; r;1 ; ) ; in particular, when r = 0; on 1 1 (1.11.13) j arg(z)j 5 2 a ; 0 < < 2 a : Here the constants ; j (j = 0; ; ), r, Dj and Cj are chosen as in the proof of Theorem 1.9. The proof of (1.11.11){(1.11.13) was based on the representation of (1.5.5) in the form m;n (z) = Qw (z) + Hp;q
1 + 2i
X j =r
Z
L
;
Dj Pw zeij ;
;
Z
L1
r;1 X j =0
;
Cj Pw zeij
2
h0(;s) 4h1(;s) +
X j =r
Dj e;ij s ;
rX ;1 j =0
3
Cj e;ij s5 z ;s ds; (1.11.14)
where h1(s) and h0(s) are given in (1.6.13) and (1.6.26), Pw (z) is the sum of the residues of the function h0 (;s)z s at the points aik (i = 1; ; n; k = 0; 1; 2; ) given in (1.1.5), the constants j , r, k, Cj and Dj are indicated in the proof of Theorem 1.9. Applying some preliminary lemmas, characterizing the terms in (1.11.14), Braaksma deduced the asymptotic expansion (1.11.11) from (1.11.14). Braaksma noted, however, that in some cases, all coecients of the above algebraic asymptotm;n(z) may have ic expansion can be taken to be equal to zero, and showed that in these cases Hp;q exponential asymptotic expansions. When n = 0, Braaksma [1, Theorem 4] proved such asymptotq;0 (z) and in ic expansions (called exponentially small expansions) presented in (1.7.5), (1.7.6) for Hp;q m; 0 (1.7.9) for Hp;q (z) in Theorem 1.10. He also showed that these asymptotic expansions hold uniformly on the sectors in Theorem 1.10 and some other regions for arg(z). His proof was based on the m;0 (z) in the form (1.5.6): representation of Hp;q Z w+i1 1 0 s m; 0 Hm; (1.11.15) Hp;q (z) = 2i p;q (;s)z ds; w;i1 which in the case m = q is reduced to the integral q Y
1 Z w+i1 h (s)z s ds; H0(z) = 2i 2 w;i1
h2(s) =
j =1 p Y i=1
;(bj ; j s) ;(ai ; i s)
(1.11.16)
29
1.11. Bibliographical Remarks and Additional Information on Chapter 1
(closely connected with E(z) in (1.6.3)), and in the case 0 < m < q is expressed in terms of H0(z) by m;0(z) = Hp;q
M X k=0
dk H0 (ze!k ) :
(1.11.17)
Here the positive integer M, real !k and complex dk are de ned by the relations: 0 Hm; p;q (s) = m;q
h2 (s)
q Y j =m+1
M X
sin[(bj ; j s)] =
k=0
dk ei!k s :
(1.11.18)
m;n (z) with > 0, Braaksma proved that (1.5.5) is reduced In the general case of the H-function Hp;q to the relation (see [1, (2.50)]) m;n(z) = Qw (z) + Hp;q
X j =
;
Dj Pw zeij +
X
;
(Cj + Dj )F zeij + O (z ! ) ;
j =
1 Z h (;s)z s ds; with F (z) = ;Pw (z) + 2i 0 L1
(1.11.19) (1.11.20)
which holds for jz j ! 1 uniformly on (1.11.21) 0 ; 12 (r + r+1 ) 5 arg(z) 5 0 ; 21 (r;1 + r ) : Here , r, j , Cj and Dj are as in the proof of Theorem 1.9, 0 is a positive number independent of z and the integers ; are de ned by ;1 5 12 (r + r;1 ; ) ; 20; 21 (r + r+1 + ) 5 +1 ; (1.11.22) 5 0 5 ; 5 5 ; < r 5 : Using estimates for some auxiliary functions, Braaksma [1, Theorem 7] obtained the asymptotic expansion (1.6.24) which holds uniformly on (1.6.25) and the following asymptotic estimates for the H-function are valid: ;
m;n(z) (Cr + Dr )E zeir Hp;q
(1.11.23)
for jz j ! 1 uniformly on ; 12 min[; r+1 ; r ] 5 arg(z) + r 5 21 min[; r ; r;1 ] ; 0 < < 14 min[; r ; r;1 ; r ; r;1 ]
(1.11.24)
(see Braaksma [1, Theorem 5]), ;
;
m;n (z) (Cr + Dr )E zeir + (Cr;1 + Dr;1 )E zeir;1 Hp;q
(1.11.25)
for jz j ! 1 uniformly on 1 ( ; ) ; 5 arg(z) + 5 1 ( ; ) + (1.11.26) r 2 r r;1 2 r r;1 1 0 < < 4 min[r;1 ; r;2 ; r ; r;1 ; r+1 ; r ; ; r + r;1 ] ;
30
Chapter 1. De nition; Representations and Expansions of the H -function
provided that r ; r;1 < (see Braaksma [1, Theorem 6]), m;n (z) Hp;q
n X 1 X
i=1 k=0 X
+
j =r
Res s=aik
Dj P
;
;s Hm;n p;q (s)z
;1 rX ; ; i j ze ; Cj P zeij + (Cr + Dr )E zeir j =0
for jz j ! 1 uniformly on (1.6.25) with 1 ; 5 arg(z) + 5 1 + r 2 2 1 0 < < 4 min[r+1 ; r ; r ; r;1 ; ] ; provided that r ; r;1 > (see Braaksma [1, Theorem 8]), and m;n (z) Hp;q
n X 1 X
Res
s=aik
(1.11.27) (1.11.28)
;s Hm;n p;q (s)z
i=1 k=0 r ;1 X ; X ; ; + Dj P zeij ; Cj P zeij + (Cr;1 + Dr;1 )E zeir;1 j =r j =0
(1.11.29)
for jz j ! 1 uniformly on (1.11.30) ; 12 ; 5 arg(z) + r;1 5 ; 21 + 0 < < 14 min[r;1 ; r;2 ; r ; r;1 ; ] ; provided that r ; r;1 > (see Braaksma [1, Theorem 9]). The results in Sections 1.5 and 1.6 were presented by the authors in Kilbas and Saigo [1]. The results in Sections 1.7 have not been published before. We also note that the asymptotic estimate (1.5.13) was earlier indicated in books by Mathai and R.K. Saxena [2, (1.6.2)] and by Srivastava, Gupta and Goyal [1, (2.2.12)]. In conclusion we indicate that Theorems 1.7 and 1.8 show the explicit power asymptotic expansion m;n (z) at in nity in the cases either (1.5.9) and the power-logarithmic one (1.5.14) of the H-function Hp;q m;n (z) in the excep 5 0 or > 0; a > 0, Theorem 1.9 gives the explicit asymptotic behavior of Hp;q m;0 (z) tional case > 0 and a = 0, and Theorem 1.10 contains the explicit asymptotic estimate of Hp;q for > 0, and either a = 0 with m < q or a > 0 with m = q. The problem of nding an explicit m;n (z) in the case > 0 and a < 0 is open, as well as that for H m;0(z) in asymptotic expansion of Hp;q p;q the case > 0, when either a < 0 with m < q or a 5 0 with m = q. We hope these problems can be solved by using the estimates (1.11.23){(1.11.26) which were established in Theorems 5, 6, 8 and 9 of Braaksma [1], in the same way as Theorem 1.9 was proved on the basis of Braaksma [1, Theorem 7]. The power and power-logarithmic asymptotic expansions of the H-function at zero in the cases 5 0 and < 0; a > 0 in Sections 1.8 and 1.9 were given by the authors in Kilbas and Saigo [1]. The asymptotic estimate (1.8.8) was earlier shown by Mathai and R.K. Saxena [2, (1.6.1)] and by Srivastava, Gupta and Goyal [1, (2.2.9)]. We note that, in the paper [1] of the authors, the asymptotic estimate (1.6.8) was proved by using the modi cation of the method suggested by Braaksma in [1] for the investigation of the asymptotic behavior of the H-function at in nity, but the formulas (1.6.8) and (1.6.8) in [1] should be corrected in accordance with Section 1.9. We also note that the asymptotic estimates for the H-function at zero presented in Sections 1.8 and 1.9 can be deduced from the corresponding estimates at in nity given in Sections 1.5 and 1.6 by using the translation formula (1.8.15) and the relations (1.8.16). The results in Section 1.10 have not been published before. For Sections 1.8{1.10.
Chapter 2 PROPERTIES OF THE
H
-FUNCTION
2.1. Elementary Properties In Sections 2.1{2.4 we suppose that the H -functions considered make sense in accordance with Theorem 1.1. The results in this section follow directly from the de nition of the H -function in Section 1.1. First we give the simplest formulas.
Property 2.1. The H -function (1.1.1) is symmetric in the set of pairs (a1; 1); ;
(an ; n ); in (an+1 ; n+1 ); ; (ap; p); in (b1; 1); ; (bm; m) and in (bm+1; m+1); ; (bq ; q ).
Property 2.2. If one of (ai; i) (i = 1; ; n) is equal to one of (bj ; j ) (j = m +1; ; q)
(or one of (ai ; i) (i = n + 1; ; p) is equal to one of (bj ; j ) (j = 1; ; m)), then the H -function reduces to a lower order one, that is, p; q and n (or m) decrease by unity. We give two examples of such reduction formulas: " # " # (a ; ) (a ; ) i i 1;p i i 2;p m;n ;1 m;n Hp;q z = Hp;1;q;1 z ; (2.1.1) (bj ; j )1;q;1; (a1; 1) (bj ; j )1;q;1 provided n = 1 and q > m; and m;n Hp;q
" # (a ; ) (ai; i )1;p;1; (b1; 1) # i i 1;p;1 m ;1 ;n z = Hp;1;q;1 z ; (bj ; j )1;q (bj ; j )2;q
"
(2.1.2)
provided m = 1 and p > n.
Property 2.3. There holds the relation m;n Hp;q
"
# " # 1 (ai ; i)1;p = H n;m z (1 ; bj ; j )1;q : q;p (1 ; a ; ) z (bj ; j )1;q i i 1;p
(2.1.3)
Property 2.4. For k > 0; there holds the relation m;n Hp;q
" # (a ; k ) (ai; i )1;p # i i 1;p m;n k = kHp;q z : z (bj ; j )1;q (bj ; k j )1;q
"
31
(2.1.4)
32
Chapter 2.
Properties of the
H -Function
Property 2.5. For 2 C ; there holds the relation m;n z Hp;q
" # (a + ; ) (ai ; i)1;p # i i i 1;p m;n z = Hp;q z : (bj ; j )1;q (bj + j ; j )1;q
"
(2.1.5)
The next six formulas follow from the de nition of the H -function in (1.1.1) and the re ection formula for the gamma function (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 1.2(6)]) (2.1.6) ;(z );(1 ; z ) = sin(z ) :
Property 2.6. For c 2 C ; > 0 and k = 0; 1; 2; ; there hold the relations # " # (a ; ) (c; ); (ai; i)1;p i i 1;p; (c; ) m +1 ;n k z = (;1) Hp+1;q+1 z ; (2.1.7) (bj ; j )1;q ; (c + k; ) (c + k; ); (bj ; j )1;q " # " # (a ; ) (c; ); (a ; ) i i 1;p; (c; ) i i 1;p m +1 ;n m;n +1 k Hp+1;q+1 z = (;1) Hp+1;q+1 z : (2.1.8) (c + k; ); (bj; j )1;q (bj ; j )1;q ; (c + k; )
+1 Hpm;n +1;q+1
"
Property 2.7. For a; b 2 C ; there hold the relations " # (a ; ) (a; 0); (ai; i)2;p # i i 2;p m;n ;1 z = ;(1 ; a)Hp;1;q z ; (bj ; j )1;q (bj ; j )1;q
"
m;n Hp;q
(2.1.9)
when Re(1 ; a) > 0 and n = 1; m;n Hp;q
"
# " # (a ; ) (ai ; i)1;p i i 1;p m ;1 ;n z = ;(b)Hp;q;1 z ; (b; 0); (bj ; j )2;q (bj ; j )2;q
(2.1.10)
when Re(b) > 0 and m = 1; " # (a ; ) (ai ; i)1;p;1 ; (a; 0) # i i 1;p;1 1 m;n ; z = ;(a) Hp;1;q z (bj ; j )1;q (bj ; j )1;q
"
m;n Hp;q
(2.1.11)
when Re(a) > 0 and p > n; and m;n Hp;q
" # # (a ; ) (ai ; i)1;p i i 1;p 1 m;n ; z = ;(1 ; b) Hp;q;1 z (bj ; j )1;q;1 (bj ; j )1;q;1; (b; 0)
"
when Re(1 ; b) > 0 and q > m.
(2.1.12)
33
2.2. Di erentiation Formulas
2.2. Di erentiation Formulas It is proved here that di erentiation of the H -function also gives the same function of greater order. From the de nition of the H -function we easily obtain the following relations:
Property 2.8.
( " d k z ! H m;n cz (ai; i)1;p p;q dz (bj ; j )1;q
#)
(;!; ); (ai; i)1;p # (bj ; j )1;q ; (k ; !; ) " (a ; ) i i 1;p; (;!; ) m +1;n k ! ; k = (;1) z Hp+1;q+1 cz (k ; !; ); (bj ; j )1;q +1 = z !;k Hpm;n +1;q +1
"
cz
(2.2.1) #
(2.2.2)
for !; c 2 C ; > 0; k
Y
j =1
" ( (a ; ) d ! m;n z dz ; cj z Hp;q az i i 1;p (bj ; j )1;q
#)
# (cj ; !; )1;k; (ai; i )1;p (bj ; j )1;q ; (cj + 1 ; !; )1;k " (a ; ) i i 1;p; (cj ; !; )1;k m +k;n k ! = (;1) z Hp+k;q+k az (cj + 1 ; !; )1;k; (bj ; j )1;q +k = z ! Hpm;n +k;q +k
"
az
(2.2.3) #
(2.2.4)
for !; a; cj 2 C (j = 1; ; k); > 0; and
" d k H m;n (cz + d) (ai; i )1;p p;q (b ; ) dz j j 1;q
#
" # (0; ); (a ; ) k i i 1;p c m;n +1 ; = (cz + d)k Hp+1;q+1 (cz + d) (bj ; j )1;q ; (k; ) " # 1 (ai; i )1;p d k H m;n p;q (cz + d) dz (bj ; j )1;q " (a ; ) k i i 1;p; (1 ; k; ) 1 c m +1;n = (cz + d)k Hp+1;q+1 (cz + d) (1; ); (bj; j )1;q
(2.2.5)
#
(2.2.6)
for c; d 2 C ; > 0. Further di erentiation formulas connect H -functions the same orders, but of di erent parameters:
34
Chapter 2. Properties of the H -Function
Property 2.9.
" d k z;b1 = 1 H m;n z (ai; i)1;p p;q (b ; ) dz j j 1;q
#!
" k (a ; ) ; k ; b = m;n 1 1 Hp;q z i i 1;p = ; z 1 (b1 + k; 1); (bj ; j )2;q
#
(2.2.7)
with m = 1; while = 1 for k > 1;
" d k z;bq = q H m;n z (ai; i )1;p p;q (b ; ) dz j j 1;q
= q
k
!
m;n z ;k;bq = q Hp;q
#!
"
z
(ai ; i)1;p (bj ; j )1;q;1; (bq + k; q )
#
(2.2.8)
with m < q; while = q for k > 1;
" d k z;(1;a1 )= 1 H m;n z ; (ai; i )1;p p;q (b ; ) dz j j 1;q
#!
" k (a ; k; ); (a ; ) 1 i i 2;p ; k ; (1;a1 )= 1 m;n ; Hp;q z 1 = ; z 1 (bj ; j )1;q
#
(2.2.9)
with n = 1; while = 1 for k > 1;
" d k z;(1;ap )= p H m;n z ; (ai; i)1;p p;q (b ; ) dz j j 1;q
= p
!
k
#!
"
m;n z ; z ;k;(1;ap )= p Hp;q
(ai; i )1;p;1; (ap ; k; p) (bj ; j )1;q
#
(2.2.10)
with p > n; while = p for k > 1. The relations (2.2.7){(2.2.10) follow from (2.2.1) and (2.2.2), if we take Property 2.2 into account.
Property 2.10. ( " (a ; ) d m;n z dz Hp;q z i i 1;p (bj ; j )1;q
#)
" # (a ; ) i i 1;p ( a 1 ; 1) m;n = Hp;q z 1 (bj ; j )1;q " m;n z (a1 ; 1; 1); (ai; i )2;p + Hp;q (b ; ) 1 j j 1;q
#
(2.2.11)
35
2.2. Di erentiation Formulas
for n = 1; ( " d m;n z (ai; i )1;p z dz Hp;q (b ; ) j j 1;q
for n 5 p ; 1;
#)
" # (a ; ) i i 1;p ( a ; 1) p m;n = Hp;q z p (bj ; j )1;q " (a ; ) ; (a ; 1; p) m;n ; Hp;q z i i 1;p;1 p p (bj ; j )1;q
( " (a ; ) d m;n z dz Hp;q z i i 1;p (bj ; j )1;q
for m = 1;
for m 5 q ; 1:
(2.2.12)
#)
" (a ; ) i i 1;p b 1 m;n = Hp;q z 1 (bj ; j )1;q
#
#
" m;n z (ai ; i)1;p ; Hp;q (b + 1; ); (b ; ) 1 1 1 j j 2;q
( " #) (a ; ) i i 1;p d m;n z dz Hp;q z (bj ; j )1;q " # (a ; ) i i 1;p b q m;n = Hp;q z q (bj ; j )1;q " (a ; ) i i 1;p m;n + Hp;q z q (bj ; j )1;q;1; (bq + 1; q )
#
(2.2.13)
#
(2.2.14)
The formulas (2.2.11){(2.2.14) are established by virtue of the following relations: ; 1s;(1 ; a1 ; 1s) = (a1 ; 1);(1 ; a1 ; 1s) + ;(2 ; a1 ; 1s); ; ;(a +ps s) = ;(aap+; 1 s) ; ;(a ; 11 + s) ; p p p p p p ; 1s;(b1 + 1s) = b1;(b1 + 1s) ; ;(b1 + 1 + 1s); ; ;(1 ; bq s; s) = ;(1 ; bbq ; s) + ;(;b 1; s) ; q q q q q q respectively, which follow from the relation (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 1.2(1)]) z ;(z ) = ;(z + 1): (2.2.15)
36
Chapter 2. Properties of the H -Function
2.3. Recurrence Relations and Expansion Formulas We give two three-term recurrence formulas which present linear combinations of the H -function with the same m; n; p and q; in which some ai and bj are replaced by ai 1 and bj 1 (i = 1; ; p; j = 1; ; q ). Such relations are called contiguous relations by Srivastava, Gupta and Goyal [1, Section 2.9]. These relations can be deduced directly by using the de nition of the H -function given in (1.1.1) and (1.1.2), if we take (2.2.15) into account.
Property 2.11. m;n (b1 p ; ap 1 + 1 )Hp;q
"
(ai ; i)1;p (bj ; j )1;q
z
#
# (ai ; i )1;p (b + 1; ); (b ; ) 1 1 j j 2;q " m;n z (ai ; i )1;p;1; (ap ; 1; p) ; 1Hp;q (bj ; j )1;q
m;n = p Hp;q
"
z
#
(2.3.1)
for m = 1 and 1 5 n 5 p ; 1; (ai ; i)1;p # (b ; ) j j 1;q " # (a ; 1; ); (a ; ) 1 1 i i 2;p m;n = q Hp;q z (bj ; j )1;q " (a ; ) m;n ; 1 Hp;q z i i 1;p (bj ; j )1;q;1; (bq + 1; q )
m;n (bq 1 ; a1 q + q )Hp;q
"
z
#
(2.3.2)
for n = 1 and 1 5 m 5 q ; 1;
Remark 2.1. A complete list of contiguous relations of the H -function may be found in
Buschman [2].
From (2.3.1) we come to the following nite series relations:
Property 2.12. For any r 2 N; m = 1 and 1 5 n 5 p ; 1; r 1 X p k=1
" 1 m;n (ai ; i)1;p;1; (ap ; 1; p) !H p;q z (b1 + k ; 1; 1); (bj ; j )2;q ; b1 + k ; (ap ; 1) 1 p
" (a ; ) i i 1;p 1 m;n !H z = p;q (b + r; ); (b ; ) 1 1 j j 2;q ; b1 + r ; (ap ; 1) 1 p
#
#
37
2.3. Recurrence Relations and Expansion Formulas " # (a ; ) i i 1;p 1 m;n !H ; ; p;q z ( a ; 1) ( b ; ) p 1 j j 1;q ; b1 ; p
(2.3.3)
" r (a ; ) k i i 1;p;1; (ap ; k + 1; p) ( ; 1) p X m;n Hp;q z (b + 1; ); (b ; ) 1 k=1 ; k ; [ap ; 1] + b1 p 1 1 j j 2;q 1 " # (a ; ) r i i 1;p;1; (ap ; r; p) ( ; 1) m;n Hp;q z = b 1 p (bj ; j )1;q ; r ; [ap ; 1] +
#
1
" # (a ; ) i i 1;p 1 m;n H ; ; p;q z b 1 p ( b ; ) j j 1 ;q ; ;[ap ; 1] +
(2.3.4)
1
r
X
k=1
m;n kp;1 1r;k [(b1 + k) p ; (ap + k ; 1) 1]Hp;q
(a ; ) ; (a + k; p) z i i 1;p;1 p (b1 + k; 1); (bj ; j )2;q
"
(ai ; i )1;p;1; (ap + r; p) # z (b1 + r + 1; 1); (bj ; j )2;q " # (a ; ) i i 1 ;p m;n z ; 1r Hp;q : (b + 1; ); (b ; ) 1 1 j j 2;q
m;n = rp Hp;q
"
#
(2.3.5)
Proof. The formula (2.3.3) is proved on the basis of (2.3.1). For simplicity let us denote the determinant ap ; 1 b1 d(b1; ap ; 1) = = b ; (ap ; 1) 1: (2.3.6) 1 p 1 p We write the H -function as H and use the notation H [b1 + 1] and H [ap ; 1] replacing b1 and ap by b1 + 1 and ap ; 1; respectively, without any change of all other parameters. Then the relations (2.3.1) and (2.3.3) are simpli ed as
d(b1; ap ; 1)H = p H [b1 + 1] ; 1 H [ap ; 1] and
(2.3.7)
r H [b + k ; 1; a ; 1] 1 X 1 p ! p k=1 1 ; b1 + k ; [ap ; 1] p
=
H H [b1 + r; ap] ! ; !: 1 1 ; b1 + r ; [ap ; 1] ; b1 ; [ap ; 1] p
(2.3.8)
p
Now applying (2.3.7) with b1 being replaced by b1 + k ; 1 and using the relation (2.2.15), we
38
Chapter 2. Properties of the H -Function
have r H [b + k ; 1; a ; 1] 1 X 1 p ! p k=1 1 ; b1 + k ; [ap ; 1] p
r
p H [b1 + k] ; d(b1 + k ; 1; ap ; 1)!H [b1 + k ; 1] p k=1 ; b1 + k ; [ap ; 1] 1
= 1
X
p
rX ;1 H [b1 + k] H [b1 + k] ! ; !; k=0 ; b1 + k ; [ap ; 1] 1 k=1 ; b1 + k ; [ap ; 1] 1 r
X
=
p
p
which implies (2.3.8) and hence (2.3.3). The relation (2.3.4) is similarly proved by another use of (2.3.7). As for (2.3.5), according to the notation (2.3.6) the left-hand side takes the form r
X
k=1
kp;1 1r;k d(b1 + k; ap + k ; 1)H [b1 + k; ap + k]:
Applying (2.3.7) and again replacing the order of summation, we nd r
X
k=1
kp;1 1r;k d(b1 + k; ap + k ; 1)H [b1 + k; ap + k] = =
r
X
k=1 r X
kp;1 1r;k ([ pH [b1 + k + 1; ap + k] ; 1 H [b1 + k; ap + k ; 1]) kp 1r;k H [b1 + k + 1; ap + k] ;
rX ;1
kp 1r;k H [b1 + k + 1; ap + k]
k=1 k=0 = rp H [b1 + r + 1; ap + r] ; 1r H [b1 + 1; ap];
and hence (2.3.5) is proved. Further, from (2.3.2) we similarly obtain the following formulas:
Property 2.13. For any r 2 N; n = 1 and 1 5 m 5 q ; 1; r 1 X q k=1
=
1
; 1 + k ; a1 + bq 1 q 1
; 1 + r ; a1 + bq 1 q
!
m;n Hp;q
! H m;n p;q
(a ; k + 1; 1); (ai; i)2;p z 1 (bj ; j )1;q;1 ; (bq + 1; q)
"
(a ; r; 1); (ai; i )2;p z 1 (bj ; j )1;q
"
#
#
39
2.3. Recurrence Relations and Expansion Formulas
;
1
; 1 ; a1 + bq 1 q
m;n !H p;q
(ai ; i )1;p # z ; (bj ; j )1;q
"
(2.3.9)
" r ( a ; 1 ; ); (a ; ) k 1 1 i i 2;p ( ; 1) q X m;n Hp;q z (b ; ) 1 k=1 ; bq + k ; [a1 ; 1] q j j 1;q;1; (bq + k ; 1; q ) 1 # " (a ; ) r i i 1;p ( ; 1) m;n Hp;q z = q (bj ; j )1;q;1; (bq + r; q) ; bq + r ; [a1 ; 1]
#
1
" # (a ; ) i i 1;p 1 m;n H ; ; p;q z q ( b ; ) j j 1 ;q ; bq ; [a1 ; 1]
(2.3.10)
1
r
X
k=1
m;n k1;1 qr;k [(bq + k ; 1) 1 ; (a1 + k ; 2) q ]Hp;q
"
(a1 + k ; 1; 1); (ai; i)2;p z (bj ; j )1;q;1; (bq + k ; 1; q )
# ( a 1 ; 1; 1); (ai ; i )2;p m;n z = qr Hp;q (bj ; j )1;q " # (a + r ; 1; ); (a ; ) 1 1 i i 2;p r m;n ; 1 Hp;q z : (bj ; j )1;q;1 ; (bq + r; q) "
#
(2.3.11)
We also give the expansions known as multiplication theorems for the H -function (see Srivastava, Gupta and Goyal [1, 2.9.]).
Theorem 2.1.
relations hold:
m;n Hp;q
"
Let 2 C and let the conditions in (1:1:6) be satis ed. Then the following
(a ; ) z i i 1;p (bj ; j )1;q
= b1 = 1 where
1
X
k=0
#
k
# 1 ; 1= 1 m;n " (ai ; i )1;p Hp;q z ; k! (b1 + k; 1); (bj ; j )2;q
(2.3.12)
m > 0; while 1= 1 ; 1 < 1 for m > 1; m;n Hp;q
"
(a ; ) z i i 1;p (bj ; j )1;q
= bq = q
1
X
k=0
#
k
# 1= q ; 1 m;n " (ai; i )1;p Hp;q z ; k! (bj ; j )1;q;1; (bq + k; q )
(2.3.13)
40 where
Chapter 2. Properties of the H -Function
q > m and 1= q ; 1 < 1; m;n Hp;q
(a ; ) z i i 1;p (bj ; j )1;q
#
1
"
= a ;1)= 1 ( 1
where n > 0 and
m;n Hp;q
k=0
(2.3.14)
Re 1= 1 > 1=2;
(a ; ) z i i 1;p (bj ; j )1;q
"
= (ap;1)= p where
k
1 ; ;1= 1 m;n " (a1 ; k; 1); (ai; i)2;p # ; Hp;q z k! (bj ; j )1;q
X
1
X
k=0
#
k
;1= p ; 1 m;n " (ai ; i)1;p;1; (ap ; k; p) # Hp;q z ; (2.3.15) k! (bj ; j )1;q
p > n and Re 1= p > 1=2:
"
1
m;n z (ai ; i)1;p Proof. By Theorem 2.2 the function z;b1 Hp;q (bj ; j )1;q (z 6= 0). Therefore for j j < jz j there holds the Taylor formula m;n (z + );b1 Hp;q
=
"
(z + ) 1
(ai; i )1;p (bj ; j )1;q
k=0
k! dz
is analytic for z 2 C
#
1 k d k (
X
#
m;n (z + );b1 Hp;q
"
(z + ) 1
(ai ; i)1;p (bj ; j )1;q
#)
=0
:
Applying (2.2.7) with = 1, we have m;n (z + );b1 Hp;q
1
"
(z + ) 1
(ai ; i )1;p (bj ; j )1;q
#
" k( ( ; ) ; b ; k m;n 1 (ai ; i)1;p 1 z H z = p;q (b1 + k; 1); (bj ; j )2;q k=0 k! X
#)
:
Setting = z 1 ; 1= 1 for j1 ; 1= 1 j < 1, we obtain "
m;n z Hp;q
1
" # 1 (1 ; 1= 1 )k (a ; ) (ai; i )1;p # b1 = 1 X i i 1;p m;n z 1 Hp;q : = (b + k; ); (b ; ) k ! (bj ; j )1;q 1 1 j j 2;q k=0
By replacing z 1 by z we arrive at (2.3.12). The relations (2.3.13){(2.3.15) are proved similarly.
41
2.4. Multiplication and Transformation Formulas
2.4. Multiplication and Transformation Formulas In this section we present the multiplication formulas for the H -function. The rst relation is an analog of the general Gauss{Legendre multiplication formula for the gamma function (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, (1.2.11)]) mY ;1
Let
; z + mk = (2 )(m;1)=2m1=2;mz ;(mz ) (m = 2; 3; 4; ): k=0
(2.4.1)
c = m + n ; p +2 q :
(2.4.2)
For ai ; bj 2 C and i ; j > 0 (i = 1; ; p; j = 1; ; q ) we shall use the symbols (k; ai); i and (k; bj ); j 1;q to abbreviate the parameter sequences
and
ai ; ; ai + 1 ; ; ; ai + k ; 1 ; i i k i 1;p k k 1;p 1;p
1;p
(2.4.3)
bj ; ; bj + 1 ; ; ; bj + k ; 1 ; ; (2.4.4) j k j 1;q k j 1;q k 1;q respectively. The following multiplication relation for the H -function follows directly from the de nition (1.1.1){(1.1.2):
Property 2.14. m;n Hp;q
2
3
(k; ai); i 1;p 7 k (ai ; i)1;p # 6 km;kn z = (2 )(1;k)c k+1 Hkp;kq 4 zk; (2.4.5) 5; (bj ; j )1;q ( k; b ) ; j j 1;q
"
where k 2 N; and , c and are given in (1.1.15), (1.1.8) and (1.1.10). To give another multiplication formula we introduce some notation. Let n; m; r; s 2 N; ai; bj ; ck ; dl 2 C and i ; j ; k; l 2 R+ and Ni; Mj ; Rk; Sl 2 N (i = 1; ; n; j = 1; ; m; k = 1; ; r; l = 1; ; s). Let
N= =
n
Y
i=1
n
X
i=1
Ni ; M =
(Ni) ; = i
m
Y
j =1
m
X
j =1
Mj ; R =
(Mj ) ; = j
r
X
k=1 r Y
Rk ; S =
s
X
l=1
k=1
(Rk ) ; = k
Sl ; s
(2.4.6)
(Sl ) :
Y
l=1
l
(2.4.7)
The symbols ((Ni; ai); i=Ni )1;n and ((Mj ; bj ); j =Mj )1;m abbreviate the parameter sequences a i ; i ; a i + 1 ; i ; ; a i + N i ; 1 ; i (2.4.8) Ni Ni 1;n Ni Ni 1;n Ni Ni 1;n
42
Chapter 2. Properties of the H -Function
and
!
!
!
bj + 1 ; j bj + Mj ; 1 ; j bj ; j ; ; ; (2.4.9) Mj Mj 1;m Mj Mj 1;m Mj Mj 1;m ; respectively, and similarly for ((Rk ; ck ); k =Rk )1;r and ((Sl; dl); l=Sl )1;s . Then there holds another multiplication relation:
Property 2.15. Hnm;n +r;m+s
"
(a ; ) ; (c ; ) z i i 1;n k k 1;r (bj ; j )1;m; (dl; l)1;s
#
= (2 )(m+n;r;s;M ;N +R+S )=2
n
Y
(Ni);a +1=2 i
i=1
m
(Mj )b ;1=2
Y
j
j =1
r
s Y ; c k +1=2 (Rk ) (Sl )dl ;1=2 k=1 l=1 Y
2
HNM;N +R;M +S z 6 6 6 4
3
i k (Ni; ai); N ; (Rk ; ck ); R i ! k 1;r 7 1;n 7 7: l j 5 ; (Sl; dl); S (Mj ; bj ); M
(2.4.10)
l 1;s
j 1;m
The next relation is a certain transformation of in nite series involving the H -function.
Property 2.16.
" # (a)k xk H m+1;n z (ai ; i)1;p; (c + k; ) p+1;q+1 (b + k; ); (bj; j )1;q k=0 k! 1 (a)k c ; a ; b) X k = ;(;( c ; b) k=0 (a + b ; c + 1)kk! (1 ; x)
1
X
Hpm+1+1;q;n+1 + b ; c) + ;(a ;( a)
(a ; ) ; (c ; a; ) z i i 1;p (b + k; ); (bj ; j )1;q
"
1
#
(c ; b)k (1 ; x)c;a;b+k ( c ; a ; b + 1) k ! k k=0 X
# (ai ; i)1;p; (c ; a; ) z ; (2.4.11) (c ; a + k; ); (bj; j )1;q where a; b; c 2 C ; > 0; j arg(1 ; x)j < ; and Re(c ; a ; b) > 0 if x = 1: Here (a)k (a 2 C ; k = 0; 1; 2; ) is the Pochhammer symbol (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 2.1.1]) de ned by a + k) (k = 1; 2; ): (2.4.12) (a)0 = 1; (a)k = a(a + 1) (a + k ; 1) = ;(;( a)
Hpm+1+1;q;n+1
"
2.5. Mellin and Laplace Transforms of the H -Function
43
The formula (2.4.11) may be derived by using the transformation formula: ;(c);(c ; a ; b) F (a; b; a + b ; c + 1; 1 ; x) 2 F1 (a; b; c; x) = ;(c ; a);(c ; b) 2 1 a + b ; c) (1 ; x)c;a;b F (c ; a; c ; b; c ; a ; b + 1; 1 ; x) (2.4.13) + ;(c);( 2 1 ;(a);(b) (j arg(1 ; x)j < ) for the Gauss hypergeometric function (2.9.2).
2.5. Mellin and Laplace Transforms of the H -Function The Mellin and Laplace transforms of a function f (x) (x > 0) are de ned by
and
Lf
(t) =
1
Z
Mf (s) =
0
Z 0
1
f (x)xs;1 dx (s 2 C )
(2.5.1)
f (x)e;txdx (t 2 C );
(2.5.2)
respectively. The theory of these transforms may be found in the books by Doetsch [1], [2], Ditkin and Prudnikov [1], Sneddon [1], Titchmarsh [3] and Widder [1]. In particular, the Mellin inversion formula is given by Z +i1 Mf (s)x;s ds M;1 f (x); (2.5.3) f (x) = 21i
;i1 while the Laplace inversion has the form Z +i1 1 Lf (t)extdt L;1 f (x); (2.5.4) f (x) = 2i
;i1 where 2 R is specially chosen. We shall consider the H -function provided that the conditions in (1.1.6) are satis ed. The rst result for the Mellin transform follows from Theorem 1.1 and the Mellin inversion theorem (see, for example, Titchmarsh [3, Section 1.5]).
Theorem 2.2. Let a = 0 and s 2 C be such that "
#
Re(bj ) < Re(s) < min 1 ; Re(ai ) ; ; 15min j i 15i5n j 5m when a > 0; and; additionally; Re(s) + Re() < ;1; when a = 0. Then the Mellin transform of the H -function exists and the relation # " #! " (a ; ) ( a ; ) i i 1 ;p i i 1;p m;n m;n x MHp;q ( s ) = H s p;q (b ; ) (bj ; j )1;q j j 1;q
(2.5.5) (2.5.6) (2.5.7)
44
Chapter 2. Properties of the H -Function
holds; where Hm;n p;q (s) is given in (1.1.2). Proof. By (1.1.4) and (1.1.5) for the poles bjl (1 5 j 5 m; l = 0; 1; 2; ) and aik (1 5 i 5 n; k = 0; 1; 2; ) of the gamma functions ;(bj + j s) (1 5 j 5 m) and ;(1 ; ai ; i s) (1 5 i 5 n); there hold the following estimates: # " Re( b ) j (1 5 j 5 m; l = 0; 1; 2; ) (2.5.8) Re(bjl) 5 Re(bj 0) 5 ; min j 15j 5 m and 1 ; Re( a ) i (1 5 i 5 n; k = 0; 1; 2; ): (2.5.9) Re(aik ) = Re(ai0) = min i 15i5 n In view of Section 1.1 we can choose the contour L = Li 1 with = Re(s) for the H -function in the left side of (2.5.7), because it follows from (2.5.8) and (2.5.9) that all poles bjl (1 5 j 5 m; l = 0; 1; 2; ) lie in the left of the contour Li 1 while all poles aik (1 5 i 5 n; k = 0; 1; 2; ) lie in the right of Li 1 . By Theorem 1.1 such an H -function exists. Hence (1.1.1) and (1.1.2) give the result in (2.5.7) according to the Mellin inversion theorem.
Corollary 2.2.1. Let a = 0; a 2 C and 2 R ( 6= 0). Let us assume that s; w 2 C
satisfy
#
"
Re(bj ) < Re(s + w) < min 1 ; Re(ai ) ; ; 15min j i 15i5n j 5m when a > 0; j arg z j < a=2; z 6= 0; and additionally; Re(s + w) + Re() < ;1; when a = 0; arg z = 0 and z 6= 0. Then the following relations hold: " #! (a ; ) i i 1;p m;n ax Mxw Hp;q (s) (b ; ) j j 1;q " ;(s+w)= (ai ; i )1;p s + w # a m;n ( > 0); = Hp;q (bj ; j )1;q
(2.5.10) (2.5.11)
(2.5.12)
(ai ; i )1;p #! (s) (b ; ) j j 1;q " # ;(s+w)=jj (1 ; b ; ) j j 1 ;q s + w a ( < 0): (2.5.13) = j j Hn;m q;p (1 ; ai ; i )1;p j j Proof. When > 0, the relation (2.5.12) follows from (2.5.7). For < 0, (2.5.13) is deduced by using (1.8.15) and (2.5.12). The general case a 2 C follows by analytic continuation by virtue of Theorem 1.1. m;n Mxw Hp;q
"
ax
The next statement presents the Laplace transform of the H -function.
45
2.5. Mellin and Laplace Transforms of the H -Function
Theorem 2.3. Let either a > 0 or a = 0; Re() < ;1; and assume "
#
min Re( bj ) > ;1; 15j 5m j when a > 0; or a = 0; = 0; and
(2.5.14)
#
"
(2.5.15) min Re( bj ) ; Re()+ 1=2 > ;1; 15j 5m j when a = 0; < 0. Then; the Laplace transform of the H -function exists and the relation # " #! " (0; 1); (a ; ) (a ; ) i i 1;p i i 1;p 1 1 m;n +1 m;n x (2.5.16) (t) = t Hp+1;q t LHp;q (bj ; j )1;q (bj ; j )1;q holds for t 2 C (Re(t) > 0). Proof. First we indicate that, if we denote by a0 the constant (1.1.7) for the H -function in the right side of (2.5.16), then a0 = a + 1 = 1 if a = 0. By (1.1.1) and (1.1.2) for the H -functions in the left and right sides of (2.5.16) we take the contour L = Li 1 ; where the choice of will depend on the relations between the constant A; B and M de ned by " # Re( b ) Re() + 1 ; (2.5.17) 1 ; Re( a ) j i ; B = ; min ; M = ; A = 1min i j 15j 5 m 5i5n for which in accordance with (1.1.1), (1.1.2), (2.5.8), (2.5.9) and (2.5.15) there hold the relations Re(bjl ) 5 B < 1; Re(aik ) = A; ch = 1
(2.5.18)
for the poles bjl (1 5 j 5 m; l = 0; 1; 2; ) of the gamma functions ;(bj + j s) (1 5 j 5 m); for the poles aik (1 5 i 5 n; k = 0; 1; 2; ) of ;(1 ; ai ; i s) (1 5 i 5 n) and for the poles ch = h + 1 (h = 0; 1; 2; ) of ;(1 ; s). If a > 0; we choose by the relations B < < min[A; 1] (B < A); B< <1 (B = A); (2.5.19) A< A): When B < A; then (2.5.18) implies all poles bjl (1 5 j 5 m; l = 0; 1; 2; ) lie in the left of the contour Li 1 ; while all poles aik (1 5 i 5 n; k = 0; 1; 2; ) and all poles ch (h = 0; 1; 2; ) lie in the right of Li 1 . When B = A; only a nite number of points s = aik may lie in the strip B = A < Re(s) < 1 and therefore we can choose Li 1 with B < < 1 such that all bjl lie in the left of Li 1 ; while all aik and ch lie in the right of Li 1 . For example, if the points aik (1 5 i 5 n; 0 5 k 5 Ni) lie in the strip B = A < Re(s) < 1; putting
c=
min
5i5n;05k5Ni
1
[Im(aik )]; d =
max
5i5n;05k5Ni
1
[Im(aik )];
we consider the rectangle = f(x; y ) : B < x < 1; c ; 1 < y < d + 1g
46
Chapter 2. Properties of the H -Function
and, then, we may choose Li 1 as a sum of the half-lines L1 = f + it; ;1 < t 5 cg and L2 = f + it; d 5 t < +1g and the curve L3 ; lying in ; with the beginning at + ic and the end at + id such that all points aik (1 5 i 5 n; 0 5 k 5 Ni) lie in the right of L3 . In the case B > A we can similarly choose Li 1 with A < < B because only a nite number of points s = bjl and s = aik may lie in the strip A < Re(s) < B . Then by Theorem 1.1 the H -functions in the left and the right sides of (2.5.16) exist. We treat the case a = 0. When = 0, can be chosen as above in (2.5.19). We note that since Re() < ;1, M > 0 when > 0; and M < 0 when < 0. Then if a = 0 and > 0; we choose by
<M A< <M B < < min[M; 1] B < < min[A; 1] B < < min[M; 1] A<
(M 5 B; M 5 A); (M 5 B; M > A); (M > B; M 5 A); (M > B; M > A; B < A); (M > B; M > A; B = A); (M > B; M > A; B > A):
(2.5.20)
(M = B; M = A); (M = B; M < A); (M < B; M = A)
(2.5.21)
If a = 0 and < 0; is chosen as
M < M < < min[A; 1] M <
and as in (2.5.19) for M < B; M < A. Similar arguments yield that, for the case a = 0, only a nite number of points s = bjl and s = aik may lie in the corresponding strips and we can choose Li 1 with in these strips. According to (2.5.18), (2.5.20), (2.5.21) we have
< M ( > 0);
> M ( < 0);
(2.5.22)
which is equivalent to + Re() < ;1. So in all cases above a = 0 and + Re() < ;1 (with di erent in the strips) and hence by Theorem 1.1 the H -functions in the left and the right sides of (2.5.16) exist. m;n (x) has Due to Corollaries 1.11.1, 1.12.1 and 1.13.1 and Remark 1.5, the H -function Hp;q the asymptotic behavior near zero of the form (1.8.8), (1.8.14) or (1.9.14), where
=
"
min Re bj 15j 5 m j
!#
in the cases = 0 or < 0; a > 0; and is given by (1.9.14) for < 0; a = 0. Therefore the integral in the left side of (2.5.16) exists. Now the relation (2.5.16) is proved directly by using (2.5.2), (1.1.1), (1.1.2) and changing the order of integration: m;n LHp;q
(a ; ) x i i 1;p (bj ; j )1;q
"
#!
(t)
47
2.5. Mellin and Laplace Transforms of the H -Function " Z (ai; i )1;p # Z 1 ;s ;tx 1 m;n H (b ; ) s ds 0 x e dx = 2i Li 1 p;q j j 1;q # " ;s Z ( a ; ) i i 1 ;p 1 1 ds; 1 m;n H = t 2i s ;(1 ; s) p;q t Li 1 (bj ; j )1;q which gives (2.5.16). This completes the proof of Theorem 2.3.
Corollary 2.3.1. Let either a > 0 or a = 0; and Re() < ;1: Let us assume ! 2 C ;
a > 0 and > 0 are such that
#
"
min Re( bj ) + Re(! ) > ;1; 15j 5 m j when a > 0; or a = 0; = 0; and # " Re( ) + 1 = 2 Re( b ) j + Re(! ) > ;1; min ; 15j 5 m j when a = 0; < 0. Then the relation " " #! (;!; ); (a ; ) (a ; ) i i 1;p i i 1;p a 1 m;n +1 ! m;n H Lx Hp;q ax ( t ) = p +1;q ! +1 (b ; ) t t (bj ; j )1;q j j 1;q holds for t 2 C (Re(t) > 0).
(2.5.23)
(2.5.24) #
(2.5.25)
Remark 2.2. The relations (2.5.7) and (2.5.16) were indicated by Srivastava, Gupta and Goyal [1, (2.4.1) and (2.4.2)] provided that > 0; a > 0; and the formulas of the form (2.5.12) and (2.5.25) were listed in Prudnikov, Brychkov and Marichev [3, (2.25.2.1) and m;n (z ) at zero in Sections 1.5 and (2.25.2.3)] provided a > 0. The asymptotic estimates of Hp;q 1.6 allow us to extend (in Theorems 2.2 and 2.3) these formulas to the case a = 0. by
In what follows the so-called generalized Laplace transform will be treated, which is de ned
Lk; f
(t ) =
Z
1 0
(xt); e;jkj(xt)1=k f (x)dx (t > 0)
(2.5.26)
for a function f (x) (x > 0) and for k; 2 R (k 6= 0). For such a transform a similar result to Theorem 2.3 may be derived.
Theorem 2.4. Let either a > 0 or a = 0; and Re() < ;1: Let k; 2 R (k 6= 0) be
such that
"
#
k min Re( bj ) > k( ; 1); 15j 5 m j when a > 0 or a = 0; = 0; while # " Re( ) + 1 = 2 Re( b ) j > k( ; 1); k min ; ; 1 5j 5 m j
(2.5.27)
(2.5.28)
48
Chapter 2. Properties of the H -Function
when a = 0; < 0. Then the generalized Laplace transform of the H -function exists and the following relations hold for t > 0: " #! (a ; ) i i 1;p m;n Lk; Hp;q x (t) (b ; ) j j 1;q " ;k (k( ; 1) + 1; k); (ai; i)1;p # k( ;1)+1 k m;n +1 k ; (2.5.29) = t Hp+1;q t (bj ; j )1;q if k > 0 and " #! (a ; ) i i 1;p m;n Lk; Hp;q x (t) (b ; ) j j 1;q # k( ;1)+1 m+1;n " jkj;k (ai ; i)1;p j k j Hp;q+1 (2.5.30) = t t (jkj( ; 1); jkj); (bj; j )1;q ; if k < 0:
Proof. Theorem 2.4 is proved similarly to Theorem 2.3 by using (1.1.1){(1.1.2), Theorem
1.1 and the asymptotic estimates near zero given in Sections 1.8 and 1.9.
2.6. Hankel Transforms of the H -Function
The Hankel transform of a function f (x) (x > 0) is de ned by
H f
(x) =
1
Z
0
(xt)1=2J (xt)f (t)dt;
(2.6.1)
where J (z ) is the Bessel function of the rst kind of order 2 C (Re( ) > ;1) (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2(2)]) de ned by 2k + 1 k X : (2.6.2) J (z) = ;( +(;k1)+ 1)k! 2z k=0 One may nd the theory of this transform in the books by Ditkin and Prudnikov [1] and Sneddon [1]. In this section we shall consider the H -function, provided that the conditions in (1.1.6) are ful lled. Using the asymptotic estimates of the H -function at zero and in nity given in Theorems 1.12 and 1.7 as well as the asymptotic estimates of J (z ) (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.13(3)]) J (z ) = O(z ) (jzj ! 0); J (z ) = O z ;1=2 (jz j ! 1; j arg(z)j < ); (2.6.3) and the known formula in Prudnikov, Brychkov and Marichev [2, 2.12.2.2] + 1 + Z 1 ; (2.6.4) xJ (ax)dx = 2a;;1 ;2 ; 1 0 ; 1+ 2 (a > 0; ;Re( ) ; 1 < Re() < 1=2);
49
2.6. Hankel Transforms of the H -Function
we obtain the following result:
Theorem 2.5. Let us assume either a > 0 or a = = 0; and Re() < ;1. Let 2 C
be such that
"
#
Re( ) > ; 21 ; Re( ) + min Re( bj ) > ; 23 ; 15j 5 m j
1 ; Re( a ) i min > 1: i 15i5 n
Then the Hankel transform of the H -function exists and the relation " #! (a ; ) i i 1;p m;n H Hp;q t (x) (b ; ) j j 1;q 2 p 1 1 1 1 ; ; ; (ai; i)1;p; 4 + 2 ; 2 +1 4 2 = x2 Hpm;n +2;q x (b4j ; j )21;q2
(2.6.5)
3
(2.6.6)
5
holds for x > 0. Proof. By (2.6.3), (1.8.8) and (1.5.13) there hold the following asymptotic estimates near zero and in nity: (xt) and
= J (xt)H m;n (xt) = O t ++1=2 p;q
1 2
(t ! +0);
=
"
min Re( bj ) 15j 5m j
#
m;n(xt) = O (t ) (t ! +1); = ; min 1 ; Re(ai ) (xt)1=2J (xt)Hp;q i 15i5 n
with addition of the multipliers [log(x)]N and [log(x)]N ; respectively, in the cases when the conditions in (1.3.1) and (1.3.2) are not valid, on which one may consult Theorems 1.8 and 1.12. Therefore in accordance with (2.6.5) the integral in the left side of (2.6.6) is convergent. For bjl in (1.1.4) and aik in (1.1.5), the assumption (2.6.5) implies "
#
Re(bjl) 5 ; min Re( bj ) < Re( ) + 23 (1 5 j 5 m; l = 0; 1; 2; ) 15j 5 m j and
ai) > 1 (1 5 i 5 n; k = 0; 1; 2; ): Re(aik ) = min 1 ; Re( i 15i5 n
Since only a nite number of points bjl and aik can lie in the strip 1 < Re(s) < Re( ) + 3=2; we can choose the contour Li 1 with (2.6.7) 1 < < Re( ) + 23 such that all poles bjl of the gamma functions ;(bj + j s) (1 5 j 5 m) lie in the left of the contour Li 1 while all poles aik of ;(1 ; ai ; i s) (1 5 i 5 n) lie in the right of Li 1 . Since Re( ) + 3=2 > 0; all poles ch = + 2h + 3=2 (h = 0; 1; 2; ) of ;(3=4 + =2 ; s=2) also lie in the right of Li 1 . Hence for the H -functions in the left and right sides of (2.6.6) the contour
50
Chapter 2. Properties of the H -Function
L = Li 1 of the integral (1.1.1) can be choosen as 0 < Re(s) < Re( ) + 3=2. Further, if we
denote by a0 ; 0 and 0 the constants (1.1.7), (1.1.8) and (1.1.10) for the H -function in the right side of (2.6.6), then it is directly veri ed that a0 = a ; 0 = ; 1 and 0 = + 1=2. Then in accordance with (1.2.20) and (1.2.21) the H -functions in the left and right side of (2.6.6) exist provided that a > 0; or a = = 0 and Re() < ;1. Now the relation (2.6.6) is proved directly by using (2.6.1) and (1.1.1){(1.1.2), and by applying the relation (2.6.4), which holds for Re(s) = under (2.6.7), such that " #! (a ; ) i i 1;p m;n H Hp;q t (x) (b ; ) j j 1;q " Z (ai ; i)1;p # Z 1 1=2 1 m;n H (xt) J (xt)t;s dt = 2i s ds Li 1 p;q (bj ; j )1;q 0 3 + ; s # " Z ; m;n (ai ; i)1;p s xs;1 2;s+1=2 4 2 2 ds; H = 21i p;q Li 1 (bj ; j )1;q ; 41 + 2 + 2s which gives (2.6.6).
Corollary 2.5.1. Let a > 0 or a = = 0 and Re() < ;1. Let ; ! 2 C ; > 0 and
> 0 be such that
"
and
Re( ) > ; 12 :
Then for a > 0; b > 0 Z 0
1
m;n (xt)! J [a(xt) ] Hp;q
1 2 = 2x a
#
Re(bj ) > ;1; Re( ) + Re(! ) + 15min j j 5m 1 ; Re(ai ) > Re(! ) ; + 1 1min i 2 5i5n
!
=
( +1)
"
bt
(2.6.8) (2.6.9) (2.6.10)
(ai; i )1;p # dt (bj ; j )1;q 2
+1 4 Hpm;n b a2 +2;q
! + 1 1 1; ; ; ; (ai; i)1;p; x (bj ; j )12;q 2 2 3 ! + 1 1 ; 2 + 2 ; 2 5 (x > 0): (2.6.11)
=
Proof. Corollary 2.5.1 may be established similarly to Theorem 2.5 if we use the asymp-
totic estimates (1.8.8), (1.5.13) and (2.6.3) and the relations # " Re() + Re(! ) + 1 (1 5 j 5 m; l = 0; 1; 2; ); Re( b ) j < Re(bjl ) 5 ; min j 15j 5 m
2.7. Fractional Integration and Di erentiation of the H -Function
51
ai ) > Re(!) ; =2 + 1 (1 5 i 5 n; k = 0; 1; 2; ); Re(aik ) = min 1 ; Re( i 15i5 n following from (1.1.4), (1.1.5), (2.6.8) and (2.6.9), and choose by Re(! ) ; =2 + 1 < < Re( ) + Re(! ) + 1 in view of (2.6.10). Note that, for the H -function in the right side of (2.6.11), a0 = a ; 0 = ; = and 0 = + (! + 1)= ; 1.
In what follows, the so-called generalized Hankel transform will be used which is de ned, for k 2 R (k 6= 0) and 2 C (Re( ) > ;3=2); by
H k; f
(x) =
1
Z
0
(xt)1=k;1=2J (jkj (xt)1=k )f (t)dt:
(2.6.12)
For such a transform a similar result to Theorem 2.5 holds.
Theorem 2.6. Let a > 0 or a = = 0 and Re() < ;1. Let 2 C ; k 2 R (k 6= 0) be
such that
"
#
ai ) > 1 + 1 ; (2.6.13) min 1 ; Re( i 2k 2 15 i5n (2.6.14) Re( ) > ; 12 : Then the generalized Hankel transform of the H -function exists and the following relation holds " #! (ai; i )1;p m;n H k; Hp;q t (x) (b ; ) j j 1;q 3 2 k=2 k 1 k k k k 1 1 m;n+1 4 2 1 ; ; ; ; (ai; i )1;p; ; + ; = jk2j 2 4 2 2 5 (2.6.15) x Hp+2;q jkj x (b2j ; j )41;q 2 2
Re( ) + min Re(bj ) > ; 1 ; 1 ; k j k 2 1 5j 5 m
for x > 0.
Proof. When k > 0, Theorem 2.6 follows from Corollary 2.5.1 when ! = 1=k ; 1=2;
a = k; = 1=k and b = = 1. If k < 0; the result is obtained similarly to the proof of Theorem 2.5.
2.7. Fractional Integration and Di erentiation of the H -Function For 2 C (Re( ) > 0); the Riemann{Liouville fractional integrals and derivatives are de ned
as follows (see Samko, Kilbas and Marichev [1, Sections 2.3, 2.4 and 5.1]): Z x 1 I0+ f (x) = ;( ) (x ;f (tt))1; dt (x > 0); 0 Z 1 f (t) dt (x > 0); I; f (x) = ;(1 ) x (t ; x)1;
(2.7.1) (2.7.2)
52
Chapter 2. Properties of the H -Function
and [Re( )]+1 Z x 1 f (t) d f ( x ) = 0+ dx ;(1 ; + [Re( )]) 0 (x ; t) ;[Re( )] dt d [Re( )]+1 I 1; +[Re( )]f (x) (x > 0); (2.7.3) = dx 0+ [Re( )]+1 Z 1 1 f (t) d D; f (x) = ; dx ;(1 ; + [Re( )]) x (t ; x) ;[Re( )] dt d [Re( )]+1 I 1; +[Re( )]f (x) (x > 0); (2.7.4) = ; dx ; respectively, where [Re( )] is the integral part of Re( ). In particular, for real > 0; (2.7.3) and (2.7.4) take the simpler forms
D
[ ]+1 Z x 1 f (t) dt (x > 0); f (x) = d D0+ dx ;(1 ; f g) 0 (x ; t)f g [ ]+1 Z 1 1 f (t) dt (x > 0); d D; f (x) = ; dx ;(1 ; f g) x (t ; x)f g
(2.7.5) (2.7.6)
where [ ] and f g are the integral and fractional parts of ; respectively. As in Sections 2.5 and 2.6 we consider the H -function under the conditions in (1.1.6). Using (1.1.1), (1.1.2), Theorem 1.1 and the asymptotic estimates for the H -function at in nity and zero given in Sections 1.5, 1.6 and 1.8, 1.9, we obtain the result for fractional integration.
Theorem 2.7. Let 2 C (Re( ) > 0); ! 2 C and > 0. Let us assume either a > 0
or a = 0; Re() < ;1. Then the following statements are valid: (i) If "
#
min Re( bj ) + Re(! ) > ;1 15j 5 m j
(2.7.7)
for a > 0 or a = 0; = 0; while "
#
min Re( bj ) ; Re()+ 1=2 + Re(!) > ;1 15j 5 m j
(2.7.8)
of the H -function exists for a = 0 and < 0; then the fractional integration transform I0+ and there holds the relation " #! (ai ; i)1;p ! m;n I0+ t Hp;q t (x) (bj ; j )1;q " # (;!; ); (ai; i)1;p m;n +1 = x!+ Hp+1;q+1 x : (2.7.9) (bj ; j )1;q ; (;! ; ; )
2.7. Fractional Integration and Di erentiation of the H -Function
(ii) If
53
Re( a ) ; 1 i + Re(! ) + Re( ) < 0 (2.7.10) max i 15i5 n for a > 0 or a = 0; 5 0; while Re(ai ) ; 1 ; Re() + 1=2 + Re(! ) + Re( ) < 0 (2.7.11) 1max i 5i5n for a = 0 and > 0; then the fractional integration transform I; of the H -function exists and there holds the relation " #! (ai ; i)1;p ! m;n I; t Hp;q t (x) (bj ; j )1;q " # (ai; i )1;p; (;!; ) m +1;n ! + = x Hp+1;q+1 x : (2.7.12) (;! ; ; ); (bj ; j )1;q Proof. First we note that if we denote by a1; 1; 1 and by a2; 2; 2 the constants (1.1.7), (1.1.8) and (1.1.10) for the H -functions in the right sides of (2.7.9) and (2.7.12), then it is directly veri ed that
a1 = a2 = a ; 1 = 2 = ; 1 = 2 = ; : (2.7.13) First we prove (i). For the H -functions in both sides of (2.7.9) we take the contour L = Li 1 ; where the choice of will depend on the relations between the constant A; B; M given in (2.5.14) and the constant C de ned by (2.7.14) C = Re(!) + 1 ; for which by (1.1.1), (1.1.2), (2.5.6), (2.5.7) and (2.7.7), (2.7.8) there hold the relations Re(bjl) 5 B < C; Re(aik ) = A; Re(ch ) = C (2.7.15) for the poles bjl (1 5 j 5 m; l = 0; 1; 2; ) of the gamma functions ;(bj + j s) (1 5 j 5 m); for the poles aik (1 5 i 5 n; k = 0; 1; 2; ) of ;(1 ; ai ; i s) (1 5 i 5 n) and for the poles ch = (! + 1 + h)= (h = 0; 1; 2; ) of ;(1 + ! ; s). Now we can choose the contour Li 1 if we put similarly as in the proof of Theorem 2.3: if a > 0 B < < min[A; C ] (B < A); B< A); if a = 0 and > 0
<M (M 5 B; M 5 A); A< <M (M 5 B; M > A); (2.7.17) B < < min[M; C ] (M > B; M 5 A); B < < min[A; C ] (M > B; M > A);
54
Chapter 2. Properties of the H -Function
if a = 0 and < 0;
M < M < < min[A; C ] M <
(M = B; M = A); (M = B; M < A); (M < B; M = A);
(2.7.18)
and as in (2.7.16) for M < B; M < A. So by Theorem 1.1 in all cases above the H -function in the left side of (2.7.9) exists. The right side also exists, because in view of (2.7.13) a0 = a > 0 and the condition a = 0; + Re() < ;1 means a0 = 0; + Re( ; ) < ;1. m;n (x) has asymptotic Due to Corollaries 1.11.1, 1.12.1 and 1.13.1 and Remark 1.5, Hp;q behavior near zero of the form (1.8.8), (1.8.14) or (1.9.13), where
=
"
min Re( bj ) 15j 5 m j
#
in the cases = 0 or < 0; a > 0; and is given by (1.9.14) for < 0; a = 0. Therefore the integral in the left side of (2.7.9) exists and this relation is proved directly by using (2.7.1) and (1.1.1), (1.1.2), by changing the order of integration and by applying the formula (Samko, Kilbas and Marichev [1, (2.44)]): t ;1 (x) = ;( ) x + ;1 (Re( ) > 0): I0+ ;( + )
(2.7.19)
Namely, we have "
(ai ; i)1;p #! (x) (bj ; j )1;q " Z (ai ; i)1;p # ; !;s 1 m;n H (x)ds = 2i s I0+ t Li 1 p;q (bj ; j )1;q # " Z ( a ; ) i i 1;p ;(! + 1 ; s) x;s ds; 1 m;n H = x +! 2i s p;q ;( + ! + 1 ; s) Li 1 (bj ; j )1;q
t! H m;n t I0+ p;q
(2.7.20)
which gives (2.7.9). The assertion (ii) is proved similarly. In fact, the existence of the H -functions in the left and right sides of (2.7.12) is proved by choosing L = Li 1 with in certain intervals and by using Theorem 1.1. For the left side integral of (2.7.12), the existence can be proved on the basis of the asymptotic behavior near in nity of the form (1.5.13), (1.5.19) or (1.6.33). The relation (2.7.12) is shown directly as (2.7.20) by using the relation (Samko, Kilbas and Marichev [1, Table 9.3(1)]):
I; t ;1 (x) = ;(1;(1; ; ; ) ) x + ;1 (Re( ) > 0; Re( + ) < 1):
(2.7.21)
2.7. Fractional Integration and Di erentiation of the H -Function
55
A similar statement for fractional di erentiation follows from Theorem 2.7 by using the relations (2.7.3), (2.7.4), if we take the formulas (2.2.1), (2.2.2), (2.1.1) and (2.1.2) into account.
Theorem 2.8. Let 2 C (Re( ) > 0); ! 2 C and > 0. Let us assume either a > 0
or a = 0; Re() < ;1. Then the following statements are valid: (i) If the condition in (2:7:7) is satis ed for a > 0 and a = 0; = 0 and the condition of the in (2:7:8) holds for a = 0 and < 0; then the fractional di erentiation transform D0+ H -function exists and there holds the relation " #! (ai ; i )1;p ! m;n D0+t Hp;q t (x) (bj ; j )1;q # " (;!; ); (ai; i)1;p m;n +1 ! ; : (2.7.22) = x Hp+1;q+1 x (bj ; j )1;q ; (;! + ; ) (ii) If (2.7.23) max Re(a i ) ; 1 + Re(! ) + 1 ; fRe( )g < 0 15i5 n i for a > 0 and a = 0; 5 0; while Re( ) + 1 = 2 Re( a ) ; 1 i + Re(! ) + 1 ; fRe( )g < 0 (2.7.24) max i ; 15i5 n for a = 0 and > 0; where fRe( )g stands for the fractional part of Re( ); then the fractional di erentiation transform D; of the H -function exists and there holds the relation " #! (ai ; i)1;p ! m;n D; t Hp;q t (x) (bj ; j )1;q " # (ai; i )1;p; (;!; ) m +1 ;n = x!; Hp+1;q+1 x : (2.7.25) (;! + ; ); (bj ; j )1;q Proof. We rst prove (2.7.25). Using (2.7.4), (2.7.12) with being replaced by = 1 ; + [Re( )]; (2.2.2) and (2.1.2) we have " #! (ai ; i)1;p ! m;n D; t Hp;q t (x) (bj ; j )1;q " #! [Re( )]+1 (ai ; i)1;p d ! m;n I;t Hp;q t (x) = ; dx (bj ; j )1;q " #) [Re( )]+1 ( (ai ; i )1;p; (;!; ) d m +1;n ! + x Hp+1;q+1 x = ; dx (;! ; ; ); (bj; j )1;q " # (ai ; i)1;p; (;!; ); (;! ; ; ) m +2;n ! + ;[Re( )];1 =x Hp+2;q+2 x ([Re( )] + 1 ; ! ; ; ); (;! ; ; ); (bj; j )1;q " # (ai ; i)1;p; (;!; ) m +1 ;n = x!; Hp+1;q+1 x ; (;! + ; ); (bj; j )1;q
56
Chapter 2. Properties of the H -Function
which is (2.7.25). The relation (2.7.22) is proved similarly by using (2.7.3), (2.7.9), (2.2.1) and (2.1.1). This completes the proof of the theorem.
Remark 2.3. When = k = 1; 2; ; the relations (2.7.22) and (2.7.25) coincide with
(2.2.1) and (2.2.2).
Remark 2.4. In the case a > 0 a relation more general than (2.7.9) was indicated by
Prudnikov, Brychkov and Marichev [3, (2.25.2.2)]. The formula (2.7.12) with real > 0 was given by Raina and Koul [3, (2.5)], but the conditions for its validity have to be corrected in accordance with (2.7.10) which for real takes the form Re( a ) ; 1 i + Re(! ) + < 0: (2.7.26) max i 15i5 n The result in (2.7.22) for a > 0 was obtained by Srivastava, Gupta and Goyal [1, (2.7.13)], but the conditions should be corrected as (2.7.7), too. The relation of the form (2.7.25) being proved for a > 0 by Raina and Koul [2, (14a)] (see also Raina and Koul [3, (2.2)] and Srivastava, Gupta and Goyal [1, (2.7.9)]) contains mistakes, and it should be replaced by (2.7.25) under the condition (2.7.27) max Re(a i) ; 1 + Re(! ) + 1 ; f g < 0: 15 i5n i
2.8. Integral Formulas Involving the H -Function
In Sections 2.5{2.7 we have proved various formulas which present the integrals of the H -function. Here we give two further integrals which generalize these relations. First we# " M;N z (ci ; i)1;P consider the integral involving the product of two H -functions. Let HP;Q (dj ; j )1;Q be the second H -function de ned by (1.1.1), which also satis es the conditions of the form (1.1.6). Let a0 be the constant a in (1.1.7) for the second H -function.
Theorem 2.9. Let a > 0, a > 0 and let 2 C , > 0, z; w 2 0
j arg(z)j < a=2;
be such that
#
"
Re(bj ) < min 1 ; Re(ai ) ; ; 15min j i 15i5n j 5m "
1 ; Re(ci ) < min Re(dj ) ; 15min
i j 15j 5M i5N
and
C
"
#
"
#
(2.8.1) (2.8.2)
#
Re(bj ) ; min Re(dj ) ; 15min j j 15 j 5 M j 5m 1 ; Re(ai ) + min 1 ; Re(ci ) : < Re() < 1min i
i 15i5N 5i5n
(2.8.3)
2.8. Integral Formulas Involving the H -Function
57
Then there holds the relation " # " # Z 1 (ai ; i)1;p (ci; i)1;P M;N ;1 m;n t Hp;q zt HP;Q wt dt 0 (bj ; j )1;q (dj ; j )1;Q " # (ai ; i)1;n ; (1 ; dj ; j ; j )1;Q; (ai; i )n+1;p m + N;n + M = w; Hp+Q;q+P zw; : (2.8.4) (bj ; j )1;m; (1 ; ci ; i; i)1;P ; (bj ; j )m+1;q Proof. First we note that, according to Corollaries 1.11.1, 1.12.1, 1.7.1 and 1.8.1, two m;n (z ) and H M;N (z ) have the asymptotic estimates at zero of the form (1.8.8) H -functions Hp;q P;Q or (1.8.14) with # " # " Re( d ) Re( b ) j j and % = min % = 15min j j ; 15j 5M j 5m respectively, and asymptotics at in nity of the form (1.5.13) or (1.5.19) with 1 ; Re( c ) 1 ; Re( a ) i i and % = ; min ; % = ; min i
i 15i5N 15i5n respectively. Then the integral in the left side of (2.8.4) exists provided that the condition (2.8.3) is satis ed. The proof of the formula (2.8.4) is based on Theorem 2.2 and Corollary 2.2.1 and on the Mellin convolution relation (Titchmarsh [3, Theorem 44]) Z 1 Mfk f g (s) = Mk (s) Mf (s) for (k f )(x) = k xt f (t) dtt : (2.8.5) 0 " # (ci; i)1;P M;N Applying the translation formula (1.8.15) to HP;Q wt (d ; ) and making the change j j 1;Q of variable t = ;1= ; we rewrite the left side of (2.8.4) in the form (2.8.5): " # " # Z 1 (ai ; i)1;p (ci ; i)1;P M;N m;n zt t;1Hp;q HP;Q wt dt (b ; ) 0 (dj ; j )1;Q j j 1;q # " # " Z 1 (1 ; dj ; j )1;Q (ai ; i)1;p 1 N;M ;1 m;n dt = t Hp;q zt HQ;P wt 0 (1 ; ci ; i)1;P (bj ; j )1;q " # " # Z 1 (ai ; i)1;p (1 ; dj ; j )1;Q 1 = z d : 1 N;M m;n ; = Hp;q HQ;P w = 0 (bj ; j )1;q (1 ; ci ; i)1;P Then the Mellin transform of the left side of (2.8.4) leads to " # " # ! Z 1 (ai ; i)1;p (ci; i)1;P M;N ;1 m;n M t Hp;q zt HP;Q wt dt (s) 0 (bj ; j )1;q (dj ; j )1;Q " #! (ai ; i)1;p 1 m;n (s) = MHp;q z (bj ; j )1;q " 1= (1 ; dj ; j )1;Q #! N;M (s): (2.8.6) M ;= HQ;P w (1 ; ci ; i)1;P
58
Chapter 2. Properties of the H -Function
According to (2.8.1) and (2.8.2) we can choose s 2 C such that "
#
Re(bj ) < Re(s) < min 1 ; Re(ai ) ; 15min j i 15i5n j 5m and
"
(2.8.7) #
1 ; Re( c ) i < Re(s) ; Re( ) < min Re( dj ) : ; 15min
15j 5M i5N i j
(2.8.8)
Now we can use Theorem 2.2 for the rst term and Corollary 2.2.1 for the second, where the conditions (2.5.5) and (2.5.10) are certi ed by (2.8.7) and (2.8.8). Applying the relations (2.5.7) and (2.5.12), we obtain "
(ai; i )1;p # M;N " (ci; i)1;P # ! HP;Q wt dt (s) (b ; ) (dj ; j )1;Q j j 1;q " # (ai ; i)1;p # N;M " (1 ; dj ; j )1;Q s ; m;n = w Hp;q s HQ;P s ; (bj ; j )1;q (1 ; ci ; i)1;P # " ( a ; ) ; (1 ; d ; ; ) ; ( a ; ) i i 1 ;n j j j 1 ;Q i i n +1 ;p m + N;n + M = ws; Hp+Q;q+P s : (bj ; j )1;m (1 ; ci ; i; i)1;P ; (bj ; j )m+1;q
1 ;1 m;n M t Hp;q 0 Z
zt
(2.8.9)
If we denote by ar the constant a in (1.1.7) for the H -function in the right side of (2.8.4), then it is directly veri ed that
ar = a + a0
(2.8.10)
and hence ar > 0. By the conditions (2.8.1) and (2.8.2) we can choose s 2 C such that "
#
1 ; Re( c ) Re( b ) i j ; 15min j ; 15min
i i5N j 5m "
Re(dj ) 1 ; Re( a ) i + min < Re(s) < 15min i j 15j 5M i5 n
#
and we can apply Corollary 2.2.1 to the right side of (2.8.4) and a direct calculation, similar to the above by using (2.5.13), shows that the Mellin transform of the right side of (2.8.4) coincides with the right side of (2.8.9). Hence by the Mellin inversion theorem, we arrive at the relation (2.8.4), which completes the proof of the theorem.
Corollary 2.9.1. If the conditions of Theorem 2:9 are satis ed; then there holds the
relation
Z
1 ;1 m;n " ; t Hp;q zt 0
(ai ; i)1;p # M;N " (ci ; i)1;P # HP;Q wt dt (bj ; j )1;q (dj ; j )1;Q " # (ai; i )1;n; (ci + i; i)1;P ; (ai; i )n+1;p m + M;n + N = w Hp+P;q+Q zw : (bj ; j )1;m ; (dj + j ; j )1;Q; (bj ; j )m+1;q
(2.8.11)
59
2.8. Integral Formulas Involving the H -Function
Proof. By virtue of the translation formula (1.8.15) we have "
(ai; i )1;p # M;N " (ci; i)1;P # I= HP;Q wt dt (b ; ) (dj ; j )1;Q j j 1;q " # " # Z 1 (1 ; bj ; j )1;q (ci; i)1;P M;N ;1 n;m ;1 = t Hq;p z t H wt dt: 0 (1 ; ai ; i )1;p P;Q (dj ; j )1;Q 1 ;1 m;n t Hp;q 0
Z
zt;
n;m (z ;1 t ) It is easy to see that the conditions of the form (2.8.1) and (2.8.2) for the function Hq;p coincide with (2.8.1) and (2.8.2). Therefore applying Theorem 2.9 and using (2.8.4), we have
I
N;m+M = w Hpn++P;q +Q
"
z;1 w;
#
(1 ; bj ; j )1;m ; (1 ; dj ; j ; j )1;Q; (1 ; bj ; j )m+1;q (1 ; ai ; i )1;n; (1 ; ci ; i; i)1;P ; (1 ; ai ; i)n+1;p
and, then, again by the translation formula (1.8.15), the relation (2.8.11) is obtained. For z = x 2 R and w = y 2 R; Theorem 2.9 remains true in the case when a = 0 or a0 = 0. We note that, if a = 0; from Sections 1.9 and 1.6 the asymptotic estimates of the m;n (z ) at zero and in nity are known when > 0 and < 0; respectively. Since H -function Hp;q for the convergence of the integral in the left side of (2.8.4) we have to take into account the asymptotic estimates both at zero and in nity, only the case = 0 is excepted. In this way we obtain the following result, where 0 and 0 denote the constants in (1.1.8) and (1.1.10) M;N (z ). for the H -function HP;Q
Theorem 2.10. Let either (a) a = = 0; Re() < ;1 and a0 > 0; (b) a > 0 and a0 = 0 = 0; Re(0) < ;1; or (c) a = = 0; Re() < ;1 and a0 = 0 = 0; Re(0) < ;1.
Let 2 C ; > 0 and x 2 R be such that the conditions in (2:8:1){(2:8:3) are satis ed. Then there holds the relation (2:8:4) for real x and y :
(ai ; i )1;p # M;N " (ci; i)1;P # dt HP;Q yt (dj ; j )1;Q (bj ; j )1;q " # (ai; i )1;n; (1 ; dj ; j ; j )1;Q; (ai; i)n+1;p m + N;n + M ; ; = y Hp+Q;q+P xy : (bj ; j )1;m ; (1 ; ci ; i; i)1;P ; (bj ; j )m+1;q 1 ;1 m;n " t Hp;q xt 0
Z
(2.8.12)
Proof. When a = = 0 or a0 = 0 = 0; then by Corollaries 1.11.1, 1.12.1, 1.7.1
m;n (z ) and H M;N (z ) at zero and and 1.8.1 we have asymptotic estimates for the H -funtions Hp;q P;Q in nity, as indicated in the proof of Theorem 2.9 and hence the integral in the left side of (2.8.12) converges. The next part of the proof is similar to that in Theorem 2.9, if we take into account the relations
r = ; 0; r = + 0 + 0;
(2.8.13)
60
Chapter 2. Properties of the H -Function
where r and r denote the constants in (1.1.8) and (1.1.10) for the H -function in the right side of (2.8.12). Applying the Mellin convolution theorem (2.8.5), Theorem 2.2 and Corollary 2.2.1 for the functions in the left side of (2.8.12) in the cases a = 0 and a0 = 0; respectively, we come to the relation (2.8.9) with w = y . The Mellin transform of the H -function in the right side of (2.8.12) gives the same result by using Corollary 2.2.1 if we take into account (2.8.10) and (2.8.13), ar > 0 in the cases (a) and (b), while in the case (c) ar = r = 0 and Re(r ) = Re( + 0 ) < ;2.
Corollary 2.10.1. If the conditions of Theorem 2:10 are satis ed; then there holds the
relation for real x and y :
(ai ; i)1;p # M;N " (ci; i)1;P # HP;Q yt dt (bj ; j )1;q (dj ; j )1;Q " # (ai ; i)1;n; (ci + i; i)1;P ; (ai; i )n+1;p m + M;n + N = y Hp+P;q+Q xy : (2.8.14) (bj ; j )1;m ; (dj + j ; j )1;Q; (bj ; j )m+1;q Proof. The proof is the same as in Corollary 2.9.1 by using (1.8.15) and Theorem 2.10. Z
1 ;1 m;n " ; t Hp;q xt 0
The results in Theorems 2.9 and 2.10 generalize those in Sections 2.5 and 2.6 (see Remark 2.5 below). Now we present a generalization of the result in Section 2.7.
Theorem 2.11. Let either a > 0 or a = 0; Re() < ;1: Let ; w; a 2 C ; > 0 and
> 0 be such that
"
#
"
#
min Re( bj ) + Re(w) > ;1; min Re( bj ) + Re( ) > 0 15j 5m 15j 5m j j for a > 0 and a = 0; = 0; while "
#
(2.8.15)
Re(bj ) ; Re() + 1=2 + Re(w) > ;1; 15min j j 5m # " (2.8.16) Re( ) + 1 = 2 Re( b ) j + Re( ) > 0
min ; 15j 5m j for a = 0 and < 0. Then the relation # " Z x (ai ; i)1;p w ;1 m;n
dt t (x ; t) Hp;q at (x ; t) 0 (bj ; j )1;q " # (;w; ); (1 ; ; ); (ai; i )1;p m;n +2 w + +
= x Hp+2;q+1 ax (2.8.17) (bj ; j )1;q ; (;w ; ; + ) holds for x > 0. Proof. First we note that if we denote by a0; 0; 0 the constants (1.1.7), (1.1.8) and (1.1.10) for the H -function in the right side of (2.8.17), then (2.8.18) a0 = a ; 0 = ; 0 = ; 21 :
2.8. Integral Formulas Involving the H -Function
61
By (1.1.1) and (1.1.2) for the H -functions in the left and right sides of (2.8.17) we take the contour L = Li 1 ; where the choice of will depend on the relations between the constants A; B and M given in (2.5.17), C in (2.7.14) and D by (2.8.19) D = Re( ) ; for which (2.7.15) and (2.8.15) imply the relations Re(bjl) 5 B < C; Re(aik ) = A; Re(cm) = C; Re(dn ) = D > B
(2.8.20)
for the poles bjl (1 5 j 5 m; l = 0; 1; 2; ) of the gamma functions ;(bj + j s) (1 5 j 5 m); for aik (1 5 i 5 n; k = 0; 1; 2; ) of ;(1 ; ai ; i s) (1 5 i 5 n); for cm = (w + 1 + m)= (m = 0; 1; 2; ) of ;(1 + w ; s) and for dn = ( + n)= (n = 0; 1; 2; ) of ;( ; s). Since B < min[C; D]; we can choose L = Li 1 in the same way as was done in the proof of Theorem 2.7(i), In fact,
B < < min[A; C; D] (B < A); B < < min[C; D] (B = A); (2.8.21) A< A): m;n (x) has the asymptotic From Corollaries 1.11.1 and 1.12.1 and Remark 1.5 the H -function Hp;q behavior at zero of the form (1.8.8) or (1.8.14), where % = min15j 5m [Re(bj = j ] in the cases = 0 or > 0; a = 0; and % is given by (1.9.14) for < 0 and a = 0. Therefore the integral in the left side of (2.8.17) exists and this relation is proved directly by using (1.1.1), (1.1.2), changing the order of integration and applying (2.7.19): # " Z x (ai ; i )1;p w ;1 m;n
dt t (x ; t) Hp;q at (x ; t) 0 (bj ; j )1;q " Z (ai ; i)1;p # 1 ; s tw;s (x)a;s ds m;n H s ;( ;
s ) I = 2i p;q 0+ Li 1 (bj ; j )1;q # " Z ( a ; ) i i 1 ;p ;( ; s);(w + 1 ; s) ;ax+ ;s ds: 1 m;n H = x +w 2i s p;q ;( + w + 1 ; s ; s) Li 1 (bj ; j )1;q
Remark 2.5. The relations (2.5.7), (2.5.12), (2.5.16), (2.5.25), (2.5.29), (2.5.30), (2.6.6), M;N [wt] with (2.6.11) and (2.6.15) can be obtained from (2.8.4) if we take the function HP;Q special parameters to coincide with one of the functions xw+s;1 ; xw e;px and xw J (x) (see the relations (2.9.4), (2.9.6) and (2.9.18) below). It should also be noted that many known integrals presented in the books by Prudnikov, Brychkov and Marichev [1]{[3], can be obtained from (2.8.4) by taking H -functions as certain elementary or special functions. Remark 2.6. The relation (2.8.4) was proved by K.C. Gupta and U.C. Jain [1] provided that a > 0; a0 > 0; > 0 and 0 > 0; while the formula (2.8.17) was obtained by G.K. Goyal [1] for a > 0; > 0 (see also Srivastava, Gupta and Goyal [1, (5.1.1) and (5.2.3)]). The
62
Chapter 2. Properties of the H -Function
relations (2.8.4) and (2.8.17) were indicated in Prudnikov, Brychkov and Marichev [3, 2.25.1.1 and 2.25.2.2] provided that a > 0; a0 > 0 and a > 0; respectively. But the conditions in the above papers and books have to be corrected in accordance with the conditions of Theorems 2.9 and 2.11.
2.9. Special Cases of the H -Function The H -function, being in generalized form, contains a vast number of special functions as its particular cases. First of all, when i = j = 1 (i = 1; ; p; j = 1; ; q ); it reduces to the Meijer G-function. Namely, " m;n p;q
H
(ai ; 1)1;p # m;n " (ai )1;p # m;n " z = Gp;q z = Gp;q z (bj ; 1)1;q (bj )1;q m Y Z 1 2i L
j =1 p Y i=n+1
;(bj + s)
;(ai + s)
n Y
a1; ; ap b1 ; ; bq
;(1 ; ai ; s)
i=1 q Y
j =m+1
;(1 ; bj ; s)
#
z ;s ds;
(2.9.1)
where L is the same contour taken for the H -function in Section 1.2. The theory of the G-function (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, Sections 5.3{5.6]) can be found in Luke [1, Chapter V], Mathai and R.K. Saxena [2], Prudnikov, Brychkov and Marichev [3, Sections 8.2 and 8.4]. We only note that some properties of such a function can be deduced from the corresponding properties of the H -function given in Sections 1.2{1.8 and in 2.1{2.8. The G-function is a generalization of a number of known special functions, in particular of the Gauss hypergeometric function 2F1 (a; b; c; z ) or the more general hypergeometric function p Fq (a1; ; ap; b1; ; bq ; z ) de ned by the series of z 2F1 (a; b; c; z ) =
1 X
(a)k (b)k z k (a; b; c 2 C ; c 6= 0; ;1; ;2; ); k=0 (c)k k!
p Fq (a1; ; ap; b1; ; bq ; z ) =
1 X
(a1)k (ap )k z k k=0 (b1)k (bq )k k!
(2.9.2) (2.9.3)
(ai ; bj 2 C ; ai ; bj 6= 0; ;1; ;2; (i = 1; ; p; j = 1; ; q )); where the Pochhammer symbol (a)k (k 2 N0 ) is given in (2.4.12). The theory of these functions is given in Erdelyi, Magnus, Oberhettinger and Tricomi [1, Chapters II and IV]. In particular, the series (2.9.2) converges for jz j < 1 and for jz j = 1; Re(c ; a ; b) > 0 and the series (2.9.3) converges for all nite z if p 5 q and for jz j < 1 if p = q + 1. A detailed account of the special cases of the G-function is available in Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 5.6], Luke [1, Section 6.4] and Mathai and R.K. Saxena [2, Chapter II]. Since all elementary and special functions as special cases of the G-function are also considered as special cases of the H -function due to the relation (2.9.1), we can write all special functions in terms of the H -function. We list here a few interesting cases of the
2.9.
Special Cases of the
63
H -Function
H -function which may be useful for the workers on integral transforms and special functions.
First we begin with the elementary functions: # " 1;0 = 1 z b= exp(;z 1= ); H0;1 z (b; ) " # (1 ; a; 1) 1;1 H1;1 z = ;(a)(1 + z );a = ;(a) 1 F0 (a; ;z ); (0; 1) " # ( + + 1; 1) 1;0 H1;1 z = z (1 ; z ) ; ( ; 1) 2 106 02 4 2
H
z
; ;
4
H
2
H01;;20 64;
z
2
4
2
2
(2.9.6) (2.9.7)
3
1 7 5 = p cos z ; 1 4 (0; 1); ; 1 2
z
; ;
(2.9.5)
3
1 7 1 ; 1 ; (0; 1) 5 = p sin z ; 2
2 106 02 4 2
(2.9.4)
(2.9.8)
3
i 7 1 ; 1 ; (0; 1) 5 = p sinh z ; 2 3
(2.9.9)
1 7 (2.9.10) 4 (0; 1); 1 ; 1 5 = p cosh z ; 2 " # (1; 1); (1; 1) 1;0 H2;2 z = log(1 z ); (2.9.11) (1; 1); (0; 1) 2 1 ; 1 ; 1 ; 1 3 7 6 (2.9.12) H21;;22 64;z 2 2 12 75 = 2 arcsin z ; (0; 1); ; ; 1 2 2 1 ; 1 ; (1; 1) 3 7 6 7 = 2 arctan z: (2.9.13) H21;;22 64z 2 12 5 2 ; 1 ; (0; 1) Next we present the H -functions reducible to the hypergeometric functions (2.9.2) and (2.9.3): " # (1 ; a; 1) a) 1;1 F (a; c; ;z ); (2.9.14) H1;2 z = ;( ;( c) 1 1 (0; 1); (1 ; c; 1) which is the so-called con uent hypergeometric function of Kummer (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 6.1]), " # (1 ; a; 1); (1 ; b; 1) a);(b) 1;2 F (a; b; c; ;z ); (2.9.15) H2;2 z = ;(;( c) 2 1 (0; 1); (1 ; c; 1) H01;;20 64;
z
64
Chapter 2.
p
Hp;q;p+1 1
"
# (1 ; ai ; 1)1;p z = (0; 1); (1 ; bj ; 1)1;q
Y
i=1 q Y j =1
;(ai ) ;(bj )
Properties of the
p Fq (a1; ; ap; b1; ; bq ; ;z ):
H -Function
(2.9.16)
The following H -function is also reduced to a function of generalized hypergeometric type: " # (1; 1); (b ; 1) j 1;q p; 1 Hq+1;p z = E (a1; ; ap : b1 ; ; bq : z ); (2.9.17) (ai; 1)1;p where E (a1; ; ap : b1; ; bq : z ) is the MacRobert E -function (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 5.2]). Now we give the H -functions which are reduced to Bessel type functions: 2
H
; ;
106 02 4
z
2
4
3
a+
;1 ;
a;
7 5
;1
z a
= 2
2 2 where J (z ) is the Bessel function of the rst kind (2.6.2); 2
H
; ;
206 02 4
z
2
4
3
a;
;1 ;
a+
7 5
;1
z a
J (z );
= 2 2 K ( z );
(2.9.18)
(2.9.19)
2 2 where K (z ) is the modi ed Bessel function of the third kind or Macdonald function (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, Section 7.2.2] and (8.9.2)); 3 2 a;;1 a ; 1 2 7 6z z (2.9.20) H12;;30 64 a ; 2 a + a ; ; 1 75 = 4 2 Y (z ); ;1 ; ;1 ; ;1 2 2 2 where Y (z ) is the Bessel function of the second kind or the Neumann function (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, Section 7.2.1] and (8.7.2)); 3 2 (a ; + 1; 1) 7 a ;z=2 W (z ); (2.9.21) H12;;20 64z 5 = z e ; 1 1 a+ + ;1 ; a; + ;1 2 2 where W; (z ) is the Whittaker function (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 6.9] and (7.2.2)); 3 2 1 + ; 1 7 6 z2 H13;;31 64 1 +2 75 4 2 ; 1 ; 2; 1 ; ;2; 1 (2.9.22) = 21; ; 12 ; 2 ; 2 ; 21 ; 2 + 2 s; (z ); where s; (z ) is the Lommel function (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, Section 7.5.5]).
2.9.
Special Cases of the
65
H -Function
Finally we present the special cases of the H -function which cannot be obtained from the G-function: H
; ;
"
z
10 02
#
(0; 1); (;; )
where J ; (z ) =
= J ; (z );
(2.9.23)
1
(;z )k k=0 ;(k + + 1) k! X
(2.9.24)
is the Bessel{Maitland function (see Marichev [1, (11.63)]); 2 6 116 13 4 2
H
; ;
z
4
+ ;1 2 + ; 1 ; ; 1 ; + ; ; ;
where (z ) = J;
2
2
2
3 7 7 5
(z ); = J;
1
+2+2k z (;1)k k=0 ;(k + + + 1);(k + + 1) 2 X
is the generalized Bessel{Maitland function (see Marichev [1, (8.2)]); " # (0; 1) 1;1 H1;2 ;z = E;(z ); (0; 1); (1 ; ; ) where E; (z ) =
1
zk k=0 ;(k + ) X
(2.9.25)
(2.9.26)
(2.9.27)
(2.9.28)
is the Mittag{Leer function (see Erdelyi, Magnus, Oberhettinger and Tricomi [3, Section 18.2]); " # " (1 ; a ; ) (ai ; i )1;p; # i i 1;p 1;p Hp;q+1 z = p q z ; (2.9.29) (0; 1); (1 ; bj ; j )1;q (bj ; j )1;q ; where p
Y
"
p q
;(ai + k i ) k 1 X (ai ; i)1;p; z i =1 z = q Y k! (bj ; j )1;q ; k=0 ;(b + k ) #
j =1
j
(2.9.30)
j
is Wright's generalized hypergeometric function (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 4.1]); 2
H02;;20 64z
3
(0; 1); ; 1
7 5
= Z (z )
(2.9.31)
66
Chapter 2.
with Z (z ) = 2
H12;;20 64z 6
with n
( )
Z 0
1 ;1 z t exp ;t ; dt
t
1 1
+1; ;
Properties of the
( 2 C ; > 0);
n n ( n; 1); 0; n1
7 7 5
= (2 )(1;n)=2n n+1=2 ( n) (z )
p
n Z (n;1)=2 1 n z n (2 ) (t ; 1) ;1=ne;zt dt (z ) = 1 n 1 ; +1; n
with ) (z ) = ( ;
Z
; + 1 ; 1
(2.9.33)
(2.9.34)
1 n 2 N; Re( ) > ; 1; Re(z ) > 0 ; n
+1 1 ; 1 ; 6 H12;;20 64z 1 (0; 1); ; ; ; 2
(2.9.32)
3
H -Function
1
3 7 7 5
) (z ) = ( ;
(2.9.35)
1 (t ; 1) ;1= t e;zt dt
(2.9.36)
> 0; Re( ) >
1 ; 1; 2 C ; Re(z ) > 0 :
According to the following integral representations in Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.12(23) and 7.12(19)] for the modi ed Bessel function of the third kind or the Macdonald function K (z ): Z 1 1 ;z(t+1=t)=2 t; ;1 dt (2.9.37) K (z ) = 2 0 e p 2 Z 1 e;zt (t2 ; 1); ;1=2 dt (Re(z ) > 0); (2.9.38) = 1 z 1 ; 2 ; the functions (2.9.34), (2.9.32) and (2.9.36) are connected with the function K; (z ) by the relations Z 1
z2
!
z
4 =2 2
(2)
(z ) = 2
z
2
K; (z );
K; (z );
2 K (z ): 2 ; (z ) = p ; z (2) 0
(2.9.39) (2.9.40) (2.9.41)
2.10. Bibliographical Remarks and Additional Information on Chapter 2 We also note that the function
= 0 and = n 2 N :
67
) ( n)(z ) in (2.9.34) is expressed via ( ; (z ) in (2.9.36) when
( n) (z ) = (2 )(n;1)=2n;( n+1=2) z n ( ;n0)(z ):
(2.9.42)
2.10. Bibliographical Remarks and Additional Information on Chapter 2 For Section 2.1. The elememtry properties of the H -function given in Section 2.1 were shown by many authors (see the books by Mathai and R.K. Saxena [2, Section 1.2] and Srivastava, Gupta and Goyal [1, Section 2.3]). Other various elementary properties of the H -function were given by Braaksma [1], Gupta [2], K.C. Gupta and U.C. Jain [1], [3], Lawrynowicz [1], Anandani [2], [3], Bajpai [1], Skibinski [1] and Chaurasia [1]. For Section 2.2. The di erentiation formulas (2.2.1){(2.2.5) were proved by K.C. Gupta and U.C. Jain [2], Nair [1], [2] and Oliver and Kalla [1], respectively. The relations (2.2.4), (2.2.5) and (2.2.6) were given in the book by Prudnikov, Brychkov and Marichev [3, (8.3.2.20), (8.3.2.18) and (8.3.2.19)]. The formulas (2.2.7){(2.2.10) were obtained by Lawrynowicz [1] (see also (2.2.7) and (2.2.9) in Prudnikov, Brychkov and Marichev [3, (8.3.2.17) and (8.3.2.16)]). Other di erentiation relations were also presented in the papers above and in the papers by A.N. Goyal and G.K. Goyal [1], Anandani [6] (see Mathai and R.K. Saxena [2, Section 1.3] and Srivastava, Gupta and Goyal [1, Section 2.7]). We also note that partial derivatives of the H -function with respect to parameters were investigated by Buschman [3], while Pathak [4] established the di erential equations for the H -function (1.1) with positive rational i and j . For Section 2.3. A number of recurrence relations for the H -function were obtained by Gupta [2], U.C. Jain [1], Agrawal [1], Anandani [2], [3], Mathur [1], Bora and Kalla [1], A. Srivastava and Gupta [1], Raina [1] and other authors (see the bibliography in the books of Mathai and R.K. Saxena [2] and of Srivastava, Gupta and Goyal [1]). They used methods based on the evaluation of an integral of a product of the H -function and some other special functions and have applied the known identities for the latter. Buschman [2] has used another simpler method, obtained 30 so-called contiguous relations and gave applications to nd nite series expansions. We present two such formulas in (2.3.1) and (2.3.2) and six nite series expansions (2.3.3){(2.3.5) and (2.3.9){(2.3.11), which hold for any r 2 N. We also indicate that the particular case r = n of the relations (2.3.3){(2.3.5) was given by Srivastava, Gupta and Goyal [1, (2.9.6){(2.9.8)]. In the proof of Theorem 2.1 we follow the method analogous to that adopted by Meijer [5] for the G-function (2.9.1). The relations (2.3.12){(2.3.15) were rst proved by Lawrynowicz [1] under some additional conditions to those given in Theorem 2.1. Shah [1]{[3] and A. Srivastava and Gupta [1] have obtained some other elementary expansion formulas (see Mathai and R.K. Saxena [2, Section 1.5] and Srivastava, Gupta and Goyal [1, Section 2.9]). Many authors have investigated the expansions of the H -functions in series of orthogonal functions such as Fourier series, Fourier{Bessel series, Fourier{Jacobi series, Neumann series, etc. Bajpai [1]{[3] has obtained expansions of the H -functions in terms of Jacobi polynomials, sine- and cosine-functions and Bessel functions. Shah [1] and Anandani [8] have proved the expansions of the H -functions in terms of the associated Legendre functions, while S.L. Soni [1] and Shah [2] derived such results in terms of Gegenbauer polynomials (see, for the formulas, other results and bibliography, Mathai and R.K. Saxena [2, Chapter 3] and Srivastava, Gupta and Goyal [1, Chapter 5]). We only note that Shah [4] considered some extensions of Theorem 2.1 and Anandani [1] has established the general formulas which give the expansion of the H -function in series of products of the generalized hypergeometric function p Fq (a1 ; ; ap; b1; ; bq ; z ) and the H -functions of lower order (see Srivastava, Gupta and Goyal [1, (5.6.2){(5.6.3)]).
Chapter 2. Properties of the H -Function
68
For Section 2.4. The multiplication formulas (2.4.5) and (2.4.10) were proved by K.C. Gupta and U.C. Jain [1], [3]. In [3] from (2.4.10) they deduced a relation between the H -function and the Meijer G-function (see Srivastava, Gupta and Goyal [1, (2.5.4)]). Such a result for rational i j (i = 1; ; p; j = 1; ; q) was proved earlier by Boersma [1], and on the basis of this result Pathak [4] established the di erential equation for the H -function when i and j (i = 1; ; p; j = 1; ; q) are positive rational numbers. Bajpai [4] and S.P. Goyal [1] have proved certain transformations of in nite series involving the H -function. In (2.4.11) we present one such result. Various nite and in nite series for the H -functions were given by R.N. Jain [1], M.M. Srivastava [1], Anandani [3]{[5], [7], Olkha [1], S.P. Goyal [1], R.K. Saxena and Mathur [1], Skibinski [1], Gupta and A. Srivastava [1], Taxak [1], and others (see Srivastava, Gupta and Goyal [1, Section 2.11] in this connection). It should be noted that many authors have investigated nite and in nite series for the H -function (see the results and bibliography in the books by Mathai and R.K. Saxena [2, Chapter 3] and Srivastava, Gupta and Goyal [1, Chapter 5]).
The relation (2.5.7) for the Mellin transform is well known and can be formally deduced from the Mellin inversion theorem (see, for example, the books by Titchmarsh [3], Sneddon [1], Ditkin and Prudnikov [1]). The formulas (2.5.12) and (2.5.25) for the Mellin and Laplace transforms of the H -function were presented in the book by Srivastava, Gupta and Goyal [1, (2.4.1) and (2.4.2)] under the conditions (2.5.10) and (2.5.23), respectively in the case when a > 0 and > 0. For a > 0 the relation (2.5.12) with w = 0; = 1 and (2.5.25) were also given by Prudnikov, Brychkov and Marichev [3, (2.25.2.1) and (2.25.2.3)]. The asymptotic results for the H -function at in nity and zero, given in Sections 1.5, 1.6 and 1.8, 1.9, allow us to extend (2.5.7), (2.5.12), (2.5.16) as well as (2.5.25) to the case when a = 0. For Section 2.5.
For Section 2.6. The formula of the form (2.6.11) with a = = 1 was given in Prudnikov, Brychkov and Marichev [3, (2.25.3.2)] without any condition of the form (2.6.10). The asymptotic estimates for the H -function at zero and in nity given in Sections 1.5 and 1.8 allow us to extend (2.6.11) as well as (2.6.6) to the case when a = = 0. We also indicate that O.P. Sharma [1] obtained the Hankel transform of the H -function (4.11.4) considered by Fox [2], and showed that the function # " x2 (ai; i)1;p;1; (ap ; 1) n +1 ;n 1 = 2 ; ; 2 (2.10.1) f (x) = x Hp;p+1 2 ( + ; 1); (bj ; j )1;p;1; (bp ; 1) is a self-reciprocal function (see (8.14.30)) with respect to the Hankel transform:
H f
(x) = f (x) (x > 0);
(2.10.2)
where bj = 1 ; aj + (2 + ; 1) j (1 5 j 5 n ; 1); bp = 1 ; ap + (2 + ; 1) 1; provided that p > n = 0; 2 C (Re() > ;1); 2 C and 2
n
X
i=2
i ;
pX ;1 i=n+1
!
i > ;1; Ref2 ; ap + (2 + ; 1) 1g > 0;
Re + + 1 ; ai > 0 (i = 1; 2; ; n):
(2.10.3)
i
In the case a > 0, fractional integration and di erentiation of the H -function were considered by Raina and Koul [1]{[3], Srivastava, Gupta and Goyal [1] and Prudnikov, Brychkov and Marichev [3]. Raina and Koul [2] probably rst considered fractional di erentiation D; in (2.7.6) with real > 0 of the H -function. However their result in [2, (14a)] (presented also in Raina and Koul [3, (2.2)] and Srivastava, Gupta and Goyal [1, (2.7.9)]) contains a mistake and should be replaced by (2.7.25) with the conditions in (2.7.23). For real > 0 the formula (2.7.12) was given by Raina and Koul [3, (2.5)], but the conditions for its validity should be corrected in line with (2.7.26). The For Section 2.7.
2.10. Bibliographical Remarks and Additional Information on Chapter 2
69
relation (2.7.22) was obtained by Srivastava, Gupta and Goyal [1, (2.7.13)], but the conditions should also be corrected in accordance with (2.7.7). A formula more general than (2.7.9) was indicated by Prudnikov, Brychkov and Marichev [3, (2.25.2.2)]. Due to the asymptotic behavior of the H -function at in nity and zero given in Sections 1.5, 1.6 and 1.8, 1.9, the formulas (2.7.9), (2.7.11), (2.7.22) and (2.7.25) can be extended to the case when a = 0. The results of this section are based on those obtained in our papers Kilbas and Saigo [4], [5], where, in the case a = 0, instead of the condition Re() < ;1 we have used the condition + Re() < ;1 while considering the H -function (1.1.1) with L = Li 1 . In our paper Saigo and Kilbas [4], these results were extended to generalized fractional integrals and derivatives with the Gauss hypergeometric function (2.9.2) in the kernel, introduced by Saigo [1] (see (7.12.45), (7.12.46) and Samko, Kilbas and Marichev [1, Section 23.2, note 18.6]). Such a generalized fractional integration and di erentiation of the H -function H2q;pp;2q (x) given by (1.11.1) was considered by Saigo, R.K. Saxena and Ram [1]. R.K. Saxena and Saigo [2] extended the results in Saigo and Kilbas [4] to generalized fractional integration and di erentiation operators with the Appell function F3 (a; a0; b; b0; c; x; y) in the kernel (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 5.7.1(8)]): F3(a; a0; b; b0; c; x; y) =
1 (a) (a0 ) (b) (b0 ) k l k l xk yl (0 < x; y < 1); ( c)k+l k! l! k;l=0 X
(2.10.4)
where (a)k is the Pochhammer symbol (2.4.12). For Section 2.8. The integral formula (2.8.4) was proved by K.C. Gupta and U.C. Jain [1] provided that a > 0, a0 > 0, > 0 and 0 > 0, and the relation (2.8.17) was obtained by G.K. Goyal [1] for a > 0 and > 0 (see also Srivastava, Gupta and Goyal [1, (5.2.1) and (5.2.3)]). Prudnikov, Brychkov and Marichev [3, (2.25.1.1) and (2.25.2.2)] indicated that the formulas (2.8.4) and (2.8.17) hold for a > 0, a0 > 0 and a > 0, respectively. By the asymptotic estimates of the H -function at in nity and zero given in Sections 1.5, 1.6 and 1.8, 1.9, the relations (2.8.4) and (2.8.17) are extended to the case a = 0, though the former is given in Theorem 2.10 only for positive z = x > 0. Many known integrals presented in the three-volume work by Prudnikov, Brychkov and Marichev [1]{[3] can be obtained from the integrals in (2.8.4) and (2.8.17) by taking the H -function as certain elementary or special function. It should be noted that there is a wide list of papers devoted to various integral formulas ( nite and in nite) involving the H -function. See the books by Mathai and R.K. Saxena [2, Chapter 2], Srivastava, Gupta and Goyal [1, Chapter 5] and Prudnikov, Brychkov and Marichev [3]. We also note that R.K. Saxena and Saigo [1] evaluated the integral of the form
"
m;n a(t ; a) (x ; t) (ct + d); (ai ; i)1;p (t ; a)! (x ; t) ;1(ct + d) Hp;q (b ; ) a j j 1;q
Z
x
#
(2.10.5)
more general than that in (2.8.17). Laddha [1] also calculated the Erdelyi{Kober type integrals generalizing the operators in (3.3.1) and (3.3.2) and involving the generalized polynomial sets of the H -function. The particular cases of the H -function as the Meijer G-function were rst given by Erdelyi, Magnus, Oberhettinger and Tricomi [1, Section 5.6] and then presented in the books by Mathai and R.K. Saxena [1, Chapter II], Mathai and R.K. Saxena [2, Section 1.7], Srivastava, Gupta and Goyal [1, Section 2.6] and Prudnikov, Brychkov and Marichev [3, Section 8.4.52]. Some of these cases were presented in the formulas (2.9.4){(2.9.22). The relations (2.9.23) and (2.9.29), when the H -function is not reduced to the G-function, were also considered in Mathai and R.K. Saxena [2, (1.7.8){(1.7.9)], Srivastava, Gupta and Goyal [1, (2.6.10){(2.6.11)] and Prudnikov, Brychkov and Marichev [3, (8.4.51.4)], while the relations (2.9.25) and (2.9.27) are found in Prudnikov, Brychkov and Marichev [3, (8.4.51.7) and (8.4.51.6)]. The formulas (2.9.31), (2.9.33) and (2.9.35) are never mentioned in the monograph literature. The modi ed Bessel type functions (2.9.32) and (2.9.34) were introduced by Kratzel in [5] and [1], For Section 2.9.
70
Chapter 2. Properties of the H -Function
respectively, who also investigated the properties of the former function in [5] and of the latter in [1]{[4]. The function in (2.9.36) was introduced by the authors and Glaeske in Kilbas, Saigo and Glaeske [1] and Glaeske, Kilbas and Saigo [1], where the relations (2.9.40){(2.9.42) were proved. Such a function was used by Bonilla, Kilbas, Rivero, Rodriguez and Trujillo [2] to solve some homogeneous di erential equations of fractional order and Volterra integral equations.
Chapter 3 H -TRANSFORM ON THE SPACE L;2 3.1. The H -Transform and the Space L;r This and the next chapters deal with the integral transform of the form
"
H f (x) =
Z
(a ; ) 1 m;n i i 1;p Hp;q xt 0 (bj ; j )1;q
"
#
f (t)dt;
(3.1.1)
#
m;n z (ap ; p) is the H -function de ned in (1.1.1). Such a transform is called an where Hp;q (bq ; q) H -transform. Most of the known integral transforms can be put" into the form# (3.1.1). In fact, for ( a m;n z i ; i)1;p is interpreted as the i = j = 1 (1 5 i 5 p; 1 5 j 5 q ) the function Hp;q (b ; ) "
j j 1;q
#
(ai )1;p Meijer G-function Gm;n p;q z (bj )1;q given in (2.9.1). Then (3.1.1) is reduced to the so-called integral transform with G-function kernel or G-transform
Gf (x) =
(a ) 1 m;n i 1;p Gp;q xt 0 (bj )1;q "
Z
#
f (t)dt:
(3.1.2)
Such a transform includes the classical Laplace and Hankel transforms given in (2.5.2) and (2.6.1). The Riemann{Liouville fractional integrals (2.7.1) and (2.7.2) and other integral transforms can be reduced to this G-transform. For the theory and historical notes the reader is referred to Samko, Kilbas and Marichev [1, xx36, 39]. There are other transforms which cannot be reduced to G-transforms but can be put into the H -transforms given in (3.1.1). They are the generalized Laplace and Hankel transforms, the Erdelyi{Kober type fractional integration operators, the transforms with the Gauss hypergeometric function as kernel, the Bessel-type integral transforms, etc. (see Sections 3.3, 3.7 and Chapters 7 and 8 below). In Chapter 5 we consider such former and latter particular cases of the H -transform (3.1.1) more precisely. In the present chapter, we study the H -transform (3.1.1) on the summable space L;2 ( 2 R), while the next chapter is devoted to that on L;r ( 2 R; 1 5 r < 1). Here, the space L;r consist of those Lebesgue measurable complex valued functions f for which
kf k;r =
1 dt 1=r r <1 jt f (t)j
Z 0
t
71
(1 5 r < 1; 2 R):
(3.1.3)
72
Chapter 3.
H -Transform on the Space L
;2
In particular, when = 1=r the space L1=r;r coincides with the space Lr (R+ ) of r-summable functions on R+ with the norm
kf kr =
1
Z
0
=r
1
jf (t)jr dt
< 1 (1 5 r < 1):
(3.1.4)
Further we shall investigate the particular aspects of the H -transforms (3.1.1) on L;r together with the main problems such as the existence, boundedness, representation, range and invertibility. We have said that the transform H under discussion is \formally" de ned by (3.1.1), and we must make this more precise. If we formally take the Mellin transform M of (3.1.1), we obtain # " ( a ; ) i i 1 ;p MH f (s) = Hm;n s M f (1 ; s); (3.1.5) p;q (bj ; j )1;q
"
#
(ai; i )1;p s is given in (1.1.2). When there is no confusion, we denote such where (bj ; j )1;q a function simply by H(s). It transpires that, for certain ranges of the parameters in H(s), (3.1.5) can be used to de ne the transform H on L;r . Namely, for certain h 2 R n f0g and 2 C , we have
Hm;n p;q
H f (x)
= hx ;
"
Z 1 +1 =h d x(+1)=h Hpm;n +1;q +1 xt dx 0
1 ( +1)
# (;; h); (ai; i)1;p f (t)dt (bj ; j )1;q ; (; ; 1; h)
(3.1.6)
or
H f (x)
= ;hx ;
1 ( +1)
Z =h d x(+1)=h 1 H m+1;n xt (ai ; i )1;p; (;; h) p+1;q+1 dx 0 (; ; 1; h); (bj ; j )1;q "
#
f (t)dt:
(3.1.7)
Due to (2.2.1), (2.2.2), (2.1.1) and (2.1.2), formal di erentiation with respect to x under the integral sign in (3.1.6) and (3.1.7) yields (3.1.1). Later we give conditions for the representability of (3.1.6), (3.1.7) as well as (3.1.1) being valid. Our main tool for studying the H -transform on L;r -space is based on the Mellin transform to which more precise investigation should be made for such spaces.
3.2. The Mellin Transform on L;r The Mellin transform M is usually de ned by (2.5.1), namely
Mf (s) =
1
Z 0
f (x)xs;1 dx
(3.2.1)
73
3.2. The Mellin Transform on L;r
for complex s = + it (; t 2 R). However, unless f 2 L;1 , the integral in (3.2.1) does not exist. But if we denote by F the Fourier transform of a function F on R de ned by
FF (x) =
Z +1
;1
F (t)eitx dt
(3.2.2)
and take f 2 L;1 , then by an elementary change of variable we obtain
Mf ( + it) = FC f (t);
where
(3.2.3)
C f (x) = ex f (ex ): (3.2.4) It is shown in Rooney [2, Lemma 2.1] that C is an isometric isomorphism of L;r onto Lr (R). Since the Fourier transform is de ned on Lr (R) for 1 5 r 5 2, the right-hand side of (3.2.3) makes sense for f 2 L;r ( 2 R; 1 5 r 5 2). From here we come to the following de nition.
De nition 3.1. For f 2 L;r ( 2 R; 1 5 r 5 2), we de ne the Mellin transform M of f
by the relation
Mf ( + it) =
Z1
;1
e(+it) f (e )d :
(3.2.5)
The relation (3.2.5) is also written as Mf (s) with Re(s) = . In particular, if f 2 L;2 \L;1 , the Mellin transform Mf (s) is given by the usual expression (2.5.1) for Re(s) = :
Property 3.1. The Mellin transform (3.2.5) has the properties (a) M is a unitary mapping of L; onto L (R): (b) For f 2 L; , there holds 2
2
2
Z +iR 1 Mf (s)x;s ds; (3.2.6) f (x) = 2i Rlim !1 ;iR where the limit is taken in the topology of L;2 and where, if F ( + it) 2 L1 (;R; R), Z +iR
;iR
F (s)ds = i
ZR
;R
F ( + it)dt:
(3.2.7)
(c) For f 2 L; and g 2 L ;; ; there holds 2
Z1 0
1
2
Z +i1 1 Mf (s) Mg (1 ; s)ds: f (x)g(x)dx = 2i ;i1
(3.2.8)
In the theory of H -transforms on L;r -spaces we require a multiplier theorem for the Mellin transform. First we give a de nition.
De nition 3.2. We say that a function m belongs to the class A; if there are extended
real number (m) and (m) with (m) < (m) such that
74
Chapter 3.
H -Transform on the Space L
;2
(a) m(s) is analytic in the strip (m) < Re(s) < (m). (b) m(s) is bounded in every closed substrip 5 Re(s) 5 , where (m) 5 5 1
5 (m).
2
1
2
(c) jm0( + it)j = O(jtj; ) as jtj ! 1 for (m) < < (m). 1
For two Banach spaces X and Y we use the notation [X; Y ] to denote the collection of bounded linear operators from X to Y , and [X; X ] is abbreviated to [X ]. There holds the following multiplier theorem in Rooney [2, Theorem 1].
Theorem 3.1. Suppose m 2 A. Then there is a transform Tm 2 [L;r ] with (m) < < (m) and 1 < r < 1 so that; if f 2 L;r with (m) < < (m) and 1 < r 5 2; there holds
the relation
MTm f (s) = m(s) Mf (s) (Re(s) = ):
(3.2.9)
For (m) < < (m) and 1 < r 5 2; the transform Tm is one-to-one on L;r ; except when m = 0. If 1=m 2 A, then for max[ (m); (1=m)] < < min[ (m); (1=m)] and for 1 < r < 1; Tm maps L;r one-to-one onto itself; and for the inverse operator Tm;1 there holds the formula
Tm;1 = T1=m:
(3.2.10)
3.3. Some Auxiliary Operators In the discussions of the next chapter we shall use special integral operators. The rst of them are the Erdelyi{Kober type fractional integrals (see Samko, Kilbas and Marichev [1, x18.1]) de ned by
;( +) Z x (x ; t ) ;1t+;1 f (t)dt;
x I0+; ; f (x) = ;( )
0
(3.3.1)
Z 1 x (3.3.2) (x) = ;( ) (t ; x ) ;1t(1; ;);1 f (t)dt x for Re( ) > 0; > 0; 2 C and x 2 R+ . We shall also work with the generalized Laplace transform de ned in (2.5.23), that is
I; ;; f
Z1 Lk; f (x) = (xt); e;jkj(xt)1=k f (t)dt 0
(3.3.3)
for k 2 Rnf0g; 2 C ; x 2 R+ , and with the generalized Hankel transform de ned in (2.6.11) Z1 H k; f (x) = (xt)1=k;1=2J jkj(xt)1=k f (t)dt 0
(3.3.4)
75
3.3. Some Auxiliary Operators
for k 2 R n f0g; Re( ) > ;3=2; x 2 R+ . The transforms (3.3.1){(3.3.4) are de ned for continuous functions f with compact support on R+ under the parameters indicated.
De nition 3.3. For 2 R we denote by L;1 the collection of functions f , measurable +
on R+ , such that
kf k;1 = ess sup jx f (x)j < 1: x2R
(3.3.5)
The boundedness properties of the transforms (3.3.1){(3.3.4) and their Mellin transforms are given by the following results in Rooney [6, Theorem 5.1].
Theorem 3.2. The following statements are valid: (a) If 1 5 r 5 1; Re( ) > 0 and < (1 + Re()); then for all s = r such that 1=s >
1=r ; Re( ); the operator I0+; ; belongs to [L;r ; L;s ] and is one-to-one. For 1 5 r 5 2 and f 2 L;r ; there holds the relation
; 1 + ; s (3.3.6) MI0+; ; f (s) = s Mf (s) (Re(s) = ): ; 1++ ; (b) If 1 5 r 5 1; Re( ) > 0 and > ;Re(); then for all s = r such that 1=s > 1=r ; Re( ); the operator I; ;; belongs to [L;r ; L;s ] and is one-to-one. For 1 5 r 5 2 and f 2 L;r ; there holds the relation s ; + Mf (s) (Re(s) = ): (3.3.7) MI; ;; f (s) = ; + + s (c) If 1 5 r 5 s 5 1; and if < 1 ; Re( ) for k > 0 and > 1 ; Re( ) for k < 0; then the operator Lk; belongs to [L;r ; L1;;s ] and is one-to-one. If 1 5 r 5 2 and f 2 L;r ; then there holds the relation MLk; f (s) = ;[k(s ; )]jkj1;k(s; ) Mf (1 ; s) (Re(s) = 1 ; ): (d) If 1 < r < 1 and (r) 5 k( ; 1=2) + 1=2 < Re() + 3=2; where 1 1 1 + 1 = 1;
(r) = max ; ;
(3.3.8) (3.3.9)
r r0 r r0 then for all s = r such that s0 = (k( ; 1=2) + 1=2);1 and 1=s + 1=s0 = 1; the operator H k; belongs to [L;r ; L1;;s ] and is one-to-one. If 1 < r 5 2 and f 2 L;r ; then there holds the
relation
MH k; f (s) =
2
jkj
1 + k s ; 1 + 1 2 Mf (1 ; s) 2 ; 21 ; k s ; 21 + 1 (Re(s) = 1 ; ):
k(s;1=2) ;
(3.3.10)
76
Chapter 3.
H -Transform on the Space L
;2
For further investigation we also need certain elementary operators. For a function f being de ned almost everywhere on R+ we denote the operators M , W and R as follows:
M f (x) = x f (x) ( 2 C ); W f (x) = f
x
(3.3.11)
( 2 R+ );
(3.3.12)
1 : 1 Rf (x) = f x x
(3.3.13)
It is easy to check that these operators have the following properties:
Lemma 3.1. Let 2 R and 1 5 r < 1. Then we have the following statements: (i) M is an isometric isomorphism of L;r onto L; ;r; and if f 2 L;r (1 5 r 5 2); Re( )
then
(ii)
MM f (s) = Mf (s + )
W is a bounded isomorphism of L;r onto itself; and if f
MW f (s) = s Mf (s)
(iii)
(Re(s) = ; Re( )):
2 L;r (1 5 r 5 2); then
(Re(s) = ):
R is an isometric isomorphism of L;r onto L1;;r ; and if f
MRf (s) = Mf (1 ; s)
(3.3.14) (3.3.15)
2 L;r (1 5 r 5 2); then
(Re(s) = 1 ; ):
(3.3.16)
The compositions between the operators R; W ; M ; I0+; ; , I;;; , Lk; and H k; will be employed in the next chapters. Note that the operator H k; cannot be commutated with M :
Lemma 3.2. Under the existence conditions of the operators I
H k; ; there
hold the following formulas:
RI0+; ; = I;;;+1;1= R;
; , I;;; , Lk;
0+;
and
RI; ;; = I0+; ;;1+1= R;
(3.3.17)
RH k; = H ;k; R;
(3.3.18)
W I0+; ; = I0+;; W ;
W I; ;; = I; ;; W ;
(3.3.19)
W Lk; = Lk; W1= ;
W H k; = H k; W1= ;
(3.3.20)
RM = M; R;
(3.3.21)
M Lk; = Lk; ; M; ;
(3.3.22)
M I; ;; = I; ;;+= M :
(3.3.23)
RLk; = L;k;1; R;
RW = W1= R; W M = ; M W ; M I0+; ; = I0+;;;= M ;
77
3.4. Integral Representations for the H -Function
= M I , I = I M and L = L1;0, then from Theorem 3.2(a),(b) and Since I0+ 0+;1;0 ; ;;1;0 Lemma 3.1(c) we have:
Corollary 3.2.1. The following statements are valid: (a) If 1 5 r 5 1; Re( ) > 0 and < 1; then for all s = r such that 1=s > 1=r ; Re( );
belongs to [L;r ; L ;Re( );s ] and is one-to-one. For 1 5 r 5 2 and f 2 L;r ; the operator I0+ there holds the relation ;MI f (s) = ; (1 ; ; s) Mf (s + ) (Re(s + ) = ): (3.3.24) 0+ ; (1 ; s) (b) If 1 5 r 5 1; Re( ) > 0 and > Re( ); then for all s = r such that 1=s > 1=r ; Re( ); the operator I; belongs to [L;r ; L ;Re( );s] and is one-to-one. For 1 5 r 5 2 and f 2 L;r ; there holds the relation ;MI f (s) = ; (s) Mf (s + ) (Re(s + ) = ): (3.3.25) ; ; ( + s) (c) If 1 5 r 5 s 5 1; and if < 1; then the operator L belongs to [L;r ; L1;;s ] and is one-to-one. If 1 5 r 5 2 and f 2 L;r ; then there holds the relation
MLf (s) = ;(s) Mf (1 ; s) (Re(s) = 1 ; ):
(3.3.26)
3.4. Integral Representations for the H -Function In this section we give the integral representation for the H -function. When there is no m;n (x); Hm;n (s) or H (x); H(s). Let confusion, we denote (1.1.1) and (1.1.2) simply by Hp;q p;q a ; ; ; be given in (1.1.7){(1.1.10) and let and be de ned by 8 Re(bi) > > ; min if m > 0; < (3.4.1) = > 15i5m i > : ;1 if m = 0; and
# " 8 > 1 ; Re( a ) j > if n > 0; < min j = > 15j5n > :1 if n = 0:
Theorem 3.3. Let < < . If any of the following conditions holds: (i) a > 0; (ii) a = 0; 6= 0 and Re() + 5 0;
(3.4.2)
78
Chapter 3.
H -Transform on the Space L
;2
(iii) a = 0; = 0 and Re() < 0; then for all x > 0 there holds the relation
" (a ; ) " (a ; ) # Z +iR i i 1;p i i 1 ;p 1 m;n m;n x H Hp;q p;q (bj ; j )1;q = 2i Rlim !1 ;iR (bj ; j )1;q
# s x;s ds;
(3.4.3)
except for x = in the case (iii) (when H (x) is not de ned). Proof. When a > 0, then (3.4.3) follows from the de nition of the H -function (1.1.1) with (1.1.2) and (1.2.20). We prove (3.4.3) for a = 0 and either < 0, or = 0 and x > . The proof for a = 0 and either > 0, or = 0 and 0 < x < is exactly similar. In the case under consideration, it follows from (1.1.1){(1.1.2) that Z H (x) = 21i x;s H(s)ds; L where L is a loop starting and ending at 1 and encircling all of the poles of ;(1 ; ai ; i s) (i = 1; 2; ; n) once in the negative direction, but encircling none of the poles of ;(bj + j s) (j = 1; 2; ; m). Let a a1 > max Im ; ; Im n 1 n and choose k; < k < . We choose L to be the loop consisting of the half-line Im(s) = ; from 1; i to k ; i , the segment Re(s) = k from k ; i to k + i and the half-line Im(s) = from k + i to 1 + i . For R > k ; , let LR denote the portion of L on which js ; j 5 R. It is clear that Z 1 x;s H(s)ds: (3.4.4) H (x) = 2i Rlim !1 LR For such an R we denote by the closed curve composed of the segment from ; iR to + iR on the line Re(s) = , the portion 1 of the circle js ; j = R clockwise from + iR to the intersecting point with LR , and the portion 2 of the circle js ; j = R clockwise from the intersecting point with LR to ; iR. Since < < , Cauchy's theorem implies that
Z
H
x;s (s)ds Z +iR Z ; s = x (s)ds ; x;s
;iR LR
0=
H
H(s)ds +
Z 1
x;s H(s)ds +
Z 2
x;s H(s)ds
for x > 0. In view of (3.4.4) it is sucient to show that lim R!1
Z
i
x;s H(s)ds = 0
(i = 1; 2):
(3.4.5)
Applying the relation (2.1.6), we represent H(s) as
H(s) = H1(s)H2(s);
(3.4.6)
79
3.4. Integral Representations for the H -Function
where
Yq
H1(s) =
j =1 Yp i=1
;(bj + j s) ;(ai + i s)
Yq ;
m+1 H2(s) = n+m;q j=Y n i=1
sin[(bj + j s) ]
sin[(ai + i s) ]
:
(3.4.7)
Now let us prove (3.4.5) for i = 1. We rst estimate H1 (s). From Stirling's formula (1.2.3) we have that, if = Rei (;=2 5 5 =2) and c 2 C , then uniformly in , as R ! 1,
p
;(c + ) 2e;Im(c) RR cos +Re(c);1=2e;R[cos + sin ];Re(c) : Hence, on 1, putting s = + ; = Rei , we have uniformly in , as R ! 1,
Yq
H1(s) = H1( + ) (2)(q;p)=2 jY=1p i=1
jRe(bj );1=2 ai );1=2 Re( i
8 0q 19 p < = X X exp :; Im @ bj ; ai A; RRe()+( +R cos ) j =1 i=1 8 9 0q 1 p < = X X R cos exp :;R(cos + sin ) ; Re @ bj ; aiA ; ; ; j =1
i=1
where ; and are given in (1.1.9), (1.1.8) and (1.1.10). Since jj 5 =2 on 1 , then
8 8 0 q 1 9 0q 19 p p < = < X X X X = exp :; Im @ bj ; ai A; 5 exp : 2 Im @ bj ; ai A ; : j=1 i=1 j =1 i=1
Hence there is a constant A1 such that
jH1(s)j 5 A1RRe()+( +R cos ) R cos e;R(cos + sin ) ;
(3.4.8)
if s 2 1 and R is suciently large. Now we estimate H2(s). If s 2 1 , s = + Rei = + + i , then by invoking the estimate sinh y 5 j sin(x + iy )j 5 cosh y we have
j sin[(bj + j s)]j 5 cosh[(Im(bj ) + j )] 5 Bj e j R sin with Bj = ejIm(bj )j (j = m + 1; ; q ): By virtue of the left inequality of (3.4.9) and = , we have
j sin[(ai + is)]j = sinh[(Im(ai) + i)] > 0 (i = 1; 2; ; n):
(3.4.9)
80
H -Transform on the Space L
Chapter 3.
;2
Since
d ; i sinh[(Im(a ) + ) ] = e;(2 i +Im(ai)) > 0; i i i d e then for = we have e; i sinh[(Im(ai ) + i ) ] = Ci with
Ci = e; i sinh[(Im(ai ) + i ) ] (i = 1; 2; ; n); and therefore
j sin[(ai + is)]j = Cie i R sin (i = 1; 2; ; n): Substituting these estimates into H2 (s) and taking into account the relations q p n m X X X X a = 0; j ; i = j ; i = 2 ; j =m+1
i=1
j =1
we obtain
i=n+1
Yq jH2(s)j 5 A2eR sin =2;
m+1 A2 = m+n;q j =Y n i=1
Bj
Ci
:
(3.4.10)
Since 5 0 and 0 < 5 =2, then R( ; =2) sin = 0. Therefore from (3.4.6), (3.4.8) and (3.4.10) we have
jH(s)j 5 ARRe()+( +R cos ) R cos e;R[cos +(;=2) sin ] 5 ARRe()+( +R cos ) R cos e;R cos (3.4.11) for s 2 1 and for suciently large R, say R > R0, with A = A1 A2 . Let us consider the case < 0. Remembering that Re() + 5 0 in the hypothesis (ii) of the theorem, if x > 0 and R > max[R0; K ] with K = e(x= )1=, we have Z ;R cos Z x;sH(s)ds 5 Ax; RRe()+ +1 =2 RR cos e;R cos x d 1 0 Z =2 ;
Re( )+
+1 = Ax R eR(log R;log K) cos d 0 Z =2 ;
Re( )+
+1 = Ax R eR(log R;log K) sin d 0 Z =2 5 Ax; RRe()+ +1 e2R(log R;log K)= d 0
= 2(log RA; log K ) x; RRe()+ (eR(log R;log K ) ; 1) ! 0
81
3.4. Integral Representations for the H -Function
as R ! 1, and thus (3.4.5) for i = 1 is proved when < 0. When = 0 and x > , we assumed Re() < 0 in the hypothesis (iii) of the theorem. Therefore if R > R0, then we have from (3.4.11) that Z Z ;R cos x;sH(s)ds 5 Ax; RRe()+1 =2 x d 1 0 =
Z =2 ;
Re( )+1 Ax R e;R cos log(x=)d 0
= Ax; RRe()+1
5 Ax; RRe()+1 =
Z =2 0
Z =2 0
e;R sin log(x=)d e;2R log(x=)=d
A x; RRe() 1 ; e;R log(x=) ! 0 2 log x
as R ! 1. The proof of (3.4.5) for i = 1 is completed. The proof for the case i = 2 is similar. Thus the theorem is proved.
Theorem 3.4. Suppose that < < and that either of the conditions a > 0 or
a = 0 and + Re() < ;1 holds. Then for x > 0, except for x = when a = 0 and = 0, the relation " (a ; ) # " (a ; ) # Z +i1 p p p p 1 m;n m;n H (3.4.12) Hp;q x = 2i t x;t dt p;q
; i 1 (bq ; q ) (bq ; q ) holds and the estimate " # Hp;q m;n x (ap; p ) 5 A x; (3.4.13) (bq; q) is valid, where A is a positive constant depending only on . Proof. By virtue of the assumptions, we nd that the relation (1.2.9) implies H( + it) 2 L1(;1; 1). So (3.4.12) follows from (3.4.3). The estimate (3.4.13) can be seen from the proof of Theorem 3.3. To conclude this section, we give the asymptotic estimate at in nity for the derivative of the function H(s) de ned in (1.1.2) which we need in the next chapter.
Lemma 3.3. There holds the estimate as jtj ! 1;
log + a1 log(it) ; a2 log(;it) + +it + O t12 : (3.4.14) Proof. It follows from (1.1.2) that for s = + it
H0( + it) = H( + it)
2m n H0(s) = H(s) 4X j (bj + j s) ; X i (1 ; ai ; is) j =1
i=1
82
Chapter 3.
+
q X j =m+1
j (1 ; bj ; j s) ;
p X i=n+1
H -Transform on the Space L
3 i (ai + is)5 ;
;2
(3.4.15)
where (z ) = ;0 (z )=;(z ) is the psi function de ned in (1.3.4). There exists the following asymptotic expansion of (z ) at in nity (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 1.18(7)]) 1 1 (3.4.16) (z ) = log z ; 2z + O z 2 (jz j ! 1): In accordance with (3.4.16) and (3.4.18) for c 2 C ; we have as jtj ! 1, (3.4.17) (c + it) = log(it) c + it; 1=2 + O t12 : Substituting this into (3.4.15), we arrive at (3.4.14) and the lemma is proved.
3.5.
L;2 -Theory
of the General Integral Transform
In this section we consider the general integral transform K of the form Z1 d ( +1) =h 1 ; ( +1) =h k(xt)f (t)dt; K f (x) = hx dx x 0 where the kernel k 2 L1;;2 , 2 C and h 2 R n f0g.
(3.5.1)
Theorem 3.5. (a) Let the transform K of the form (3:5:1) be in [L;2; L1;;2]; then
k 2 L1;;2 . If we set for 6= 1 ; (Re() + 1)=h
! (t) (3.5.2) + 1 ; (1 ; + it)h a.e. then ! 2 L1 (R); and for f 2 L;2 there holds the formula MK f (1 ; + it) = ! (t) Mf ( ; it) a.e. (3.5.3) (b) Conversely; for given ! 2 L1(R); 2 R and h 2 R+; there is a transform K 2 [L;2 ; L1;;2 ] so that (3:5:3) holds for f 2 L;2 . Moreover; if 6= 1 ; (Re() + 1)=h; then K f is representable in the form (3:5:1) with the kernel k given in (3:5:2): (c) Under the hypotheses of (a) or (b) with ! 6= 0 a.e.; K is a one-to-one transform from L;2 into L1;;2 ; and if in addition 1=! 2 L1 (R); then K maps L;2 onto L1;;2 . Further; for f; g 2 L;2; the relation Mk (1 ; + it) =
Z1
is valid.
0
f (x)
K g (x)dx =
Z 1 0
Kf
(x)g (x)dx
(3.5.4)
Proof. First we treat (a). We suppose that K , given in (3.5.1), is in [L;2; L1;;2], where 6= 1 ; (Re() + 1)=h. We consider the case > 1 ; (Re() + 1)=h. For a > 0, let 8 (+1)=h;1 a:
83
3.5. L;2 -Theory of the General Integral Transform
Then
kgak; =
a
Z
2
0
t2f[(Re)()+1]=h+ ;1g;1 dt
=
1 2
< 1;
which means ga 2 L;2 . Hence
Kg
d (+1)=h Z 1 x k(xt)t(+1)=h;1dt (x) = hx1;(+1)=h dx
1
d = hx1;(+1)=h dx
x
Z
0
0
(+1)=h;1k( )d = hk(x)
almost everywhere, so that K g1 = hk. Therefore since K 2 [L;2 ; L1;;2 ], we have that k 2 L1;;2 . Since f 2 L;2 and k 2 L1;;2 , by using the Schwartz inequality Z
b a
b
Z
f (x)g (x)dx 5
a
=
!1 2
jf (x)j dx 2
b
Z
a
=
!1 2
jg(x)j dx 2
(3.5.6)
(;1 5 a < b 5 1); we have
( +1)
x
=h
1
Z 0
k(xt)f (t)dt =
( +1)
x
=h
1 n 1=2;
Z
t
0
5 x[Re()+1]=h
on
k(xt)
1 1;
Z 0
t
o
t;1=2+ f (t) dt 2
k(xt)
dt 1=2 kf k;2 t
= x ;1+[Re()+1]=hkkk1;;2 kf k;2 = o(1) as x ! +0. Hence after integrating both sides of (3.5.1), we obtain for x > 0 Z 0
Z 1 x (+1)=h;1 (+1)=h t f (t)dt = hx k(xt)f (t)dt:
K
(3.5.7)
0
Now for x > 0 and Re(s) + [Re() + 1]=h > 1, we have
hx(+1)=h+s;1 : + 1 ; h(1 ; s)
Mgx (s) =
(3.5.8)
Since f 2 L;2 and gx 2 L;2 , from (3.2.8), we obtain x
Z 0
t(+1)=h;1
Kf
(t)dt =
Z
1
0
Kf
gx (t)
(t)dt
Z +i1 Mgx (s) MK f (1 ; s)ds = 21i
=
;i1 hx(+1)=h Z 1; +i1
2i
; ;i1
1
x;s MK f (s)
ds
+ 1 ; hs
hx ;1+(+1)=h Z 1 ;it MK f (1 ; + it) x dt: = 2 + 1 ; (1 ; + it)h ;1
(3.5.9)
84
Chapter 3.
Similarly, from (3.2.8) and (3.3.15) we nd hx(+1)=h
1
Z
0
k(xt)f (t)dt = hx(+1)=h =h
Z
1
H -Transform on the Space L
;2
W1=xk (t)f (t)dt
0
; +i1 ;s x Mk (s) Mf (1 ; s)ds 1; ;i1 hx ;1+(+1)=h Z 1 ;it
= hx 2i
( +1)
Z 1
x Mk (1 ; + it) Mf ( ; it)dt: 2 ;1 Substituting (3.5.9) and (3.5.10) into (3.5.7), denoting MK f (1 ; + it) ; Mk (1 ; + it) Mf ( ; it) F (t) = + 1 ; (1 ; + it)h and writing x = e;y , we obtain for all y 2 R that
=
1 iyt e F (t)dt = 0: ;1
Z +
(3.5.10)
(3.5.11) (3.5.12)
According to property (a) of the Mellin transform in Section 3.2, M 2 [L;2 ; L2(R)] for any 2 R. Therefore
MK f (1 ; + it);
Mg1 ( ; it) =
Mk (1 ; + it);
h ; + 1 ; (1 ; + it)h
Mf ( ; it)
belong to L2 (R); and F (t) in (3.5.11) is also in L2 (R). Hence (3.5.12) means that F (t) = 0 a.e. De ning ! by (3.5.2), we obtain (3.5.3) in view of (3.5.11). It remains to show that ! 2 L1 (R). It follows from (3.5.3) that, if f 2 L;2 , then ! (t) Mf ( ; it) 2 L2 (R): Due to the property (a) in Section 3.2, M maps L;2 onto L2(R) and thus ! (t) (t) 2 L2 (R) for any 2 L2 (R). Therefore from Halmos [1, Problem 51] ! 2 L1 (R). This completes the proof of (a) for > 1 ; (Re() + 1)=h. If < 1 ; (Re() + 1)=h, the proof is similar if we replace ga(t) in (3.5.5) by the function ha (t) de ned for a > 0 by 8 < 0 if 0 < t < a; ha (t) = : (+1)=h;1 (3.5.13) t if t > a: Now we prove (b). We suppose that ! 2 L1 (R) and f 2 L;2 . By the fact in Section 3.2 that M is a unitary mapping of L1;;2 onto L2 (R), there is a unique function g 2 L1;;2 such that Mg (1 ; + it) = ! (t) Mf ( ; it). We de ne K by K f = g: Then (3.5.3) holds. K is also a linear operator, namely, if fi 2 L;2 and ci 2 R (i = 1; 2), then MK [c1f1 + c2f2 ] (1 ; + it) = ! (t) M[c1f1 + c2f2 ] ( ; it)
= c1! (t) Mf1 ( ; it) + c2 ! (t) Mf2 ( ; it)
= c1 Mf1 (1 ; + it) + c2 Mf2 (1 ; + it) = M[c1K f1 + c2 K f2 ] (1 ; + it);
85
3.5. L;2 -Theory of the General Integral Transform
which implies that K (c1f1 + c2f2 ) = c1 K f1 + c2K f2 . Further, it follows from the same property in Section 3.2 that, taking ! (t) = ! (;t), we have
kK f k ;; = kMK f k = k!Mf k 5 k!k1 kMf k = k!k1 kf k; ; 1
2
2
2
2
2
where k! k1 is the L1 (R)-norm of ! . This means that K 2 [L;2 ; L1;;2 ]. We suppose that 6= 1 ; (Re() + 1)=h and let the function k(t) be de ned by (3.5.2). Then k 2 L1;;2 by Property 3.1(c), because of 1=(p + it) 2 L2(R) for a constant p 6= 0. If < 1 ; (Re() + 1)=h and ha (t) is given in (3.5.13), then
Mhx (s) =
;hx =h s; : + 1 ; h(1 ; s) ( +1)
+
1
(3.5.14)
From (3.5.13), (3.2.8), (3.5.14), (3.5.3), (3.5.2) and (3.3.15), if x > 0 then similarly to (3.5.9) we have 1 (+1)=h;1 t f (t)dt x Z 1 = hx (t) f (t)dt
K
Z
0
K
Z +i1 Mhx (s) MK f (1 ; s)ds = 21i Z = 21
;i1 1 ;hx(+1)=h+ +it;1
MK f (1 ; ; it)dt
;1 + 1 ; h(1 ; ; it) xit ; h (+1)=h+ ;1 Z 1 ! (t) Mf ( + it)dt = 2 x ;1 + 1 ; h(1 ; ; it) Z 1 xit Mk (1 ; ; it) Mf ( + it)dt = ;2h x(+1)=h+ ;1 ;1 Z 1; +i1 x1; ;s Mk (s) Mf (1 ; s)ds = 2;ih x(+1)=h+ ;1 1; ;i1 Z 1; +i1 MW1=xk (s) Mf (1 ; s)ds = 2;ih x(+1)=h 1; ;i1 h (+1)=h Z 1; +i1 Mk(xt) (s) Mf (1 ; s)ds = ; 2i x 1; ;i1 Z 1 (+1)=h
= ;hx
0
k(xt)f (t)dt:
Di erentiating this relation, we arrive at (3.5.1). Similarly for the case > 1 ; (Re()+1)=h, the formula (3.5.8) for the function ga(t) in (3.5.5) is used, and the precise calculations are omitted. Finally we prove (c). We suppose that ! 6= 0 a.e. Then if f 2 L;2 and K f = 0, it follows from (3.5.3) that ! (t) Mf ( ; it) = 0 a.e., and hence Mf ( ; it) = 0 a.e. This implies that f = 0 a.e. which means that K is one-to-one. We suppose that 1=! 2 L1 (R).
86
Chapter 3.
H -Transform on the Space L
;2
In accordance with (b), there is a transform T 2 [L1;;2 ; L;2 ] such that if g 2 L1;;2 , then 1 Mg (1 ; ; it) a.e. MT g ( + it) = ! (;t) Thus by (3.5.3), we have MK T g (1 ; + it) = ! (t) MT g ( ; it) = Mg (1 ; + it):
So for all g 2 L1;;2 ; we have the identity K T g = g which means that K maps L;2 onto L1;;2 . Finally, if f; g 2 L;2 , from (3.2.8) and (3.5.3) we obtain Z 0
1
f (x)
K g (x)dx = 21i
= 21 = 21 =
+i1
Z
Mf (s) MK g (1 ; s)ds
;i1 1
Mf ( + it) MK g (1 ; ; it)dt
Z +
;1 1
Z +
Mf ( + it)! (;t) Mg ( + it)dt
;1 1 1 ! (t)Mf ( ; it)Mg ( ; it)dt 2 ;1 1 Z +1 Z +
MK f (1 ; + it) Mg (1 ; [1 ; + it])dt
= 2
;1 Z 1; +i1 M f (s) Mg (1 ; s)ds = 21i 1; ;i1 Z 1
K
=
0
Kf
(x)g (x)dx:
This completes the proof of Theorem 3.5.
3.6.
L;2 -Theory
of the H -Transform
The results of Theorem 3.5 may be applied to obtain the L;2 -theory of the (3.1.1). For this we need a de nition.
H -transform
De nition 3.4. Let the function H(s) = Hm;n p;q (s) be given in (1.1.2) and let the real
numbers and be de ned by (3.4.1) and (3.4.2), respectively. We call the exceptional set EH of H the set of real numbers such that < 1 ; < and H(s) has a zero on the line Re(s) = 1 ; .
Theorem 3.6. We suppose that (a) < 1 ; < ;
and that either of the conditions
3.6. L;2 -Theory of the H -Transform
87
(b) a > 0; or (c) a = 0; (1 ; ) + Re() 5 0
holds. Then we have the following results: (i) There is a one-to-one transform H 2 [L;2; L1;;2] so that (3:1:5) holds for Re(s) = 1; and f 2 L;2 . If a = 0; (1 ; ) + Re() = 0 and 2= EH ; then the operator H maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then the relation (3:5:4) holds for H : Z
0
1
H g (x)dx =
f (x)
1
Z
0
Hf
(x)g (x)dx:
(3.6.1)
(iii) Let f 2 L; , 2 C and h > 0: If Re() > (1 ; )h ; 1; then H f is given in (3:1:6); 2
namely; H f (x)
" # Z 1 (;; h); (a ; ) i i 1;p d m;n +1 (+1)=h Hp+1;q+1 xt f (t)dt: = hx dx x 0 (bj ; j )1;q ; (; ; 1; h) When Re() < (1 ; )h ; 1; H f is given in (3:1:7) : H f (x)
;
1 ( +1)
=h
(3.6.2)
" # Z 1 (a ; ) i i 1;p ; (;; h) d m +1 ;n f (t)dt: (3.6.3) = ;hx1;(+1)=h dx x(+1)=h Hp+1;q+1 xt 0 (; ; 1; h); (bj ; j )1;q (iv) The transform H is independent of in the sense that, for and e satisfying the f assumptions (a), and either (b) or (c), and for the respective transforms H on L;2 and H f f for f 2 L on Le ;2 given in (3:1:5); then H f = H ;2 \ Le ;2. Proof. Let !(t) = H(1 ; + it). By virtue of (1.1.2), (3.4.1), (3.4.2) and the condition (a) the function H(s) is analytic in the strip < Re(s) < . In accordance with (1.2.9) and the condition (b) or (c), ! (t) = O(1) as jtj ! 1. Therefore ! 2 L1 (R), and hence we obtain from Theorem 3.5(b) that there exists a transform H 2 [L;2 ; L1;;2 ] such that MH f (1 ; + it) = H(1 ; + it) Mf ( ; it) for f 2 L;2 . This means that the equality (3.1.5) holds for Re(s) = 1 ; . Since H(s) is analytic in the strip < Re(s) < and has isolated zeros, then ! (t) 6= 0 almost everywhere. Thus we obtain from Theorem 3.5(c) that H 2 [L;2 ; L1;;2 ] is a one-to-one transform. If a = 0, (1 ; )+Re() = 0 and is not in the exceptional set of H, then 1=! 2 L1(R), and again from Theorem 3.5(c) we obtain that H transforms L;2 onto L1;;2 . This completes the proof of the rst assertion (i) of the theorem. Further, if f 2 L;2 and g 2 L;2 , then the relation (3.6.1) is valid according to Theorem 3.5(c), which is the assertion (ii). Let us prove (3.6.2). Let f 2 L;2 and Re() > (1 ; )h ; 1. To show the relation (3.6.2), it is sucient to calculate the kernel k in the transform (3.5.1) for such . From (3.5.2) we have the equality 1 Mk (1 ; + it) = H(1 ; + it) + 1 ; (1 ; + it)h
88
Chapter 3.
H -Transform on the Space L
;2
or, for Re(s) = 1 ; 1 + 1 ; hs : Then from (3.2.6) we obtain the expression for the kernel k, namely Z 1; +iR 1 ;s H(s) x k(x) = 21i Rlim !1 1; ;iR + 1 ; hs ds; where the limit is taken in the topology of L;2 . According to (1.1.2) we have H(s) + 11; hs = H(s) ;(1;(1; ;(;(;;)1); ;hshs) ) # " ( ; ; h ) ; ( a ; ) i i 1 ;p +1 = Hm;n s : p+1;q+1 (bj ; j )1;q ; (; ; 1; h)
Mk (s) = H(s)
(3.6.4)
(3.6.5)
We denote by 1 ; 1 ; a1 ; 1; 1 the constants in (3.4.1), (3.4.2), (1.1.7), (1.1.8), (1.1.10) +1 for this Hm;n p+1;q+1 . Then 1 = ; 1 = min[ ; (1 + Re())=h]; a1 = a ; 1 = ; 1 = ; 1. Thus, it follows that
(a)0 < 1 ; < ; 1
1
from Re() > (1 ; )h ; 1, and either of the conditions:
(b)0 a > 0; or (c)0 a = 0; (1 ; ) + Re( ) = (1 ; ) + Re() ; 1 5 ; 1 1 1
1
1
holds. Applying Theorem 3.4 for x > 0, except possibly for x = , we obtain that the equality (;; h); (ai; i )1;p) # x (bj ; j )1;q ; (; ; 1; h) Z 1; +iR 1 ;s (Hf )(s) x (3.6.6) = 21i Rlim !1 1; ;iR + 1 ; hs ds holds almost everywhere. Then, (3.6.4) and (3.6.6) yield that the kernel k is given by +1 Hpm;n +1;q +1
"
+1 k(x) = Hpm;n +1;q +1
# (;; h); (ai; i)1;p x ; (bj ; j )1;q ; (; ; 1; h)
"
and (3.6.2) is proved. The relation (3.6.3) is proved similarly to (3.6.2), if we use the equality H(s) = ;H(s) ;(hs ; ; 1) + 1 ; hs ;(hs ; ) " (ai ; i)1;p; (;; h) # m +1;n = ;Hp+1;q+1 s (; ; 1; h); (bj ; j )1;q
(3.6.7)
3.6. L;2 -Theory of the H -Transform
89
instead of (3.6.5), and hence (iii) is proved. Lastly, let us prove (iv). If f 2 L;2 \ Le ;2 and Re() > max[(1 ; )h ; 1; (1 ; e)h ; 1] f f are given in or Re() < min[(1 ; )h ; 1; (1 ; e)h ; 1], then both transforms H f and H (3.6.2) or (3.6.3), respectively, which shows that they are independent of .
Corollary 3.6.1. Let < and let one of the following conditions hold: (b) a > 0; (e) a = 0; > 0 and < ; Re() ; (f) a = 0; < 0 and > ; Re() ;
(g) a = 0; = 0 and Re() 5 0:
Then the H -transform can be de ned on L;2 with < < . Proof. When 1 ; < < 1 ; , by Theorem 3.6, if either a > 0 or a = 0; (1 ; ) + Re() 5 0 is satis ed, then the H -transform can be de ned on L;2 , which is also valid when < < . Hence the corollary is clear in cases (b) and (g). When > 0 and < ;Re()=, the assumption < yields that there exists a number such that < 1 ; 5 ; Re()= and 1 ; < , which are required. For the case (f) the situation is similar, that is, there exists of the forms > 1 ; = ; Re()= and < 1 ; . Thus the proof is completed.
Theorem 3.7. Let < 1 ; < and suppose either of the the following conditions
holds:
(b) a > 0; (d) a = 0; (1 ; ) + Re() < 0: Then for x > 0;
Hf
(x) is given in (3:1:1) for f 2 L;2 ; namely,
Hf
(x) =
Z
1 m;n " Hp;q xt 0
(ai ; i)1;p # f (t)dt: (bj ; j )1;q
(3.6.8)
Proof. We denote by the function Hpm;n;q in (3.6.2) instead of for the H -function e
+1 +1 +1
(1.1.1). By (1.1.10) e = ; 1 and since (1 ; ) + Re() < 0, then (1 ; ) + Re(e ) < ;1. +1 It follows from Theorem 1.2 in Section 1.2 that if Re() > (1 ; )h ; 1, then Hpm;n +1;q +1 in (3.6.2) is continuously di erentiable on R+ . Therefore we can di erentiate under the integral sign in (3.6.2). Applying the relations (2.2.7) and (2.1.1), we arrive at (3.6.8) provided that the integral in (3.6.8) exists. The existence of this integral is proved on the basis of (3.4.13). Indeed, we choose 1 and
2 so that < 1 < 1 ; < 2 < . According to (3.4.13) there are constants A1 and A2 such that for almost all t > 0, the inequalities m;n(t)j 5 A t; i (i = 1; 2) jHp;q i
90
Chapter 3.
H -Transform on the Space L
;2
hold. Therefore, using the Schwartz inequality (3.5.6), we have 1 m;n Hp;q (xt)f (t) dt 0
Z
5
Z
1
0
H (xt)t
2
5
4A x; 1 1
=x
Z 1 0
+A2 x; 2
=x
1
kf k;
2
=
!1 2
; ; 1 );1 dt
t
1
Z
=
1 2
= ; 2 dt
1 2
2(1
t
; ; 2 );1 dt
2(1
!1 2 3
=
5
kf k;
2
= Cx ;1 < 1; where n
o
C = A1[2(1 ; ; 1)];1=2 + A2[2( 2 + ; 1)];1=2 kf k;2; and the theorem is proved. In conclusion of this section we indicate the conditions for the H -transform (3.6.8) to be de ned on some L;2 -space.
Corollary 3.7.1. Let < and let one of the following conditions hold: (b) a > 0; (h) a = 0; > 0 and < ; Re() + 1 ; (i) a = 0; < 0 and > ; Re() + 1 ; (j) a = 0; = 0 and Re() < 0:
Then the H -transform can be de ned (3:6:8) on L;2 with < < . Proof. The proof of this statement is similar to those of Corollary 3.6.1.
3.7. Bibliographical Remarks and Additional Information on Chapter 3
For Section 3.1. The general integral transforms with the H -functions as kernels were introduced by Gupta and P.K. Mittal [1] and R. Singh [1] in 1970 in the forms " # Z 1 (a ; ) i i 1:p m;n H f (x) = x 0 H p;q xt (b ; ) f (t)dt (x > 0) (3.7.1) j j 1;q and " # Z 1 (a ; ) i i 1:p m;n H f (x) = x 0 H p;q cxt (b ; ) f (t)dt (x > 0); (3.7.2) j j 1;q respectively. It should be noted that the form (3.1.1) for the H -transform was rst suggested by C.B.L. Verma [1] (1966), and that some H -transforms were implicitly studied by Fox [2] (1961) and
3.7. Bibliographical Remarks and Additional Information on Chapter 3
91
Kesarwani [11] (1965) while investigating the H -functions as symmetrical and unsymmetrical Fourier kernels, respectively, and by R.K. Saxena [8] while considering the inversion of the Mellin{Barnes integrals of the form (1.1.2). As indicated in Section 3.1, most of the known integral transforms can be put into the form (3.1.1). These are the G-transform (3.1.2) and its particular cases such as the classical Laplace and Hankel transforms (2.5.2) and (2.6.1), the Riemann{Liouville fractional integrals (2.7.1) and (2.7.2), the even and odd Hilbert transforms (8.3.10) and (8.3.11), the Varma-type integral transforms (7.2.1), (7.2.15), (7.3.1) and (7.3.13) with the Whittaker functions as kernels, the integral transform (7.4.1) with parabolic cylinder function in the kernel, the integral transforms (7.5.1), (7.5.13), (7.6.1) and (7.6.12) with hypergeometric functions 1F1 and 1 F2 in the kernels, the integral transforms (7.7.1), (7.7.2), (7.7.21), (7.7.22), (7.8.1), (7.8.2), (7.8.23) and (7.8.24) with the Gauss hypergeometric function in the kernels, the generalized Stieltjes transform (7.9.1) and the p Fq -transforms (7.10.1). There also exist transforms which cannot be reduced to G-transforms but can put into the H -transforms given in (3.1.1). Such examples are the cosine- and sine-transforms (8.1.2) and (8.1.3), the Erdelyi{Kober type fractional integration operators (3.3.1) and (3.3.2), the transforms with the Gauss hypergeometric function as kernel proved by R.K. Saxena [9], R.K. Saxena and Kumbhat [1], [3], McBride [1], Kumbhat [1] (see (7.12.37), (7.12.38), (7.12.43) and (4.11.25), (4.11.26)), the Wright transform p q in (7.11.1), the Laplace type transform L ;k in (7.1.1), the generalized Laplace and Hankel transforms Lk; ; H k; in (3.3.3) and (3.3.4), the extended Hankel transform H ;l in (8.4.1), Hankel type transforms H ;;$;k;; h;1; h;2 ; b;1; b;2 in (8.5.1) and (8.6.1){(8.6.4), Y - and H -transforms ) in in (8.7.1) and (8.8.1), the Meijer transform K in (8.9.1), the Bessel type transforms K ; L(m) ; L(; (8.10.1), (8.10.2) and (8.11.1), the modi ed Hardy{ and Hardy{Titchmarsh transforms J; ; Ja;b;c;! in (8.12.6) and (8.12.1) and the Lommel{Maitland transform J ; in (8.13.1). It should be noted that, though many authors studied H -transforms of the forms (3.1.1), (3.7.1), (3.7.2) and modi ed H -transforms, most of the investigations were devoted to studying the inversion of H -transforms in spaces Lr (R+ ) (1 5 r < 1), their Mellin transform and the relation of fractional integration by parts of the form (3.6.1). The boundedness of such H -transforms in the space Lr (R+ ) were studied in several papers (see Sections 4.11 and 5.7 in this connection). The mapping properties such as the boundedness and the respresentation of the H -transform (3.1.1) in the space L;2 were presented in Section 3.6. Such properties together with the range and invertibilty of such an H -transform in the spaces L;r (1 5 r 5 1) will be given in Chapter 4 by extending results in this chapter. As for further results we indicate that Vu Kim Tuan [1] studied the factorization properties of the H -transform (3.1.1) in the special functional space L2 , and Nguyen Thanh Hai and Yakubovich [1] investigated general integral convolution for these integral transforms. A series of papers was devoted to studying integral transforms with H -function kernels in spaces of generalized functions and Abelian theorems for them. Classical Abelian theorems give the asymptotic behavior of the integral transform (H f )(x) near zero or in nity on the basis of the known asymptotic behavior of f (t) as t ! 1 or t ! 0, respectively. R.K. Saxena [10] obtained classical Abelian theorems for more general integral transforms than (3.1.1) with H -function kernel of the form " # Z 1 (a ; ) i i 1:p ; !xt m;n H ! f (x) = e H p;q xt f (t)dt (x > 0) (3.7.3) (bj ; j )1;q 0 with positive ! > 0 and extended the results to generalized functions. R.K. Saxena [10] proved that if ( > ;1) and are given real numbers such that t; f (t) is absolutely continuous on [0; 1) and lim f (t) = 0; t! lim+0 t; f (t) = ; (3.7.4) t!+1
then
(!x)+1 lim x!+1 H (1=!)
where the function in the denominator is
"
+1 H (z ) = H m;n p+1;q z
H ! f (x) = ;
(3.7.5)
(;; 1); (ai ; i)1:p : (bj ; j )1;q #
(3.7.6)
92
Chapter 3.
H -Transform on the Space L
;2
He also extended this result to generalized functions and gave other sucient conditions for (3.7.5) to be valid. Joshi and Raj.K. Saxena [1]{[3] investigated the H -transform of the form (3.7.3), where the variable xt of the H -function in the integrand is replaced by (xt) with > 0 and > 0. They obtained in [1] the same assertions as those given above by R.K. Saxena [10]. They further proved in [2] two structure theorems for the generalized functions (represented by such generalized H -transforms) in terms of di erential operators acting on functions or on measures, and used such structures in [3] to establish the complex inversion formula for this generalized H -transform and to discuss its uniqueness. See also Brychkov and Prudnikov [1, Section 8.2] in this connection. Carmichael and Pathak [2] extended the above results of R.K. Saxena [10] to complex x by proving Abelian theorems in a wedge domain in the right half-plane, de ned quasi-asymptotic behavior of such H -transformable generalized functions, proved a structure theorem for generalized functions having such quasi-asymptotic behavior and gave applications to obtain the asymptotic behavior of the H -transform of these generalized functions. Similar results for the H -transform (3.1.1) were obtained by Carmichael and Pathak [1]. Malgonde and Raj.K. Saxena extended the H -transform of the form " # Z 1 (a + b ; ) i i i 1:m m +1 ; 0 H f (x) = H m;m+1 xt f (t)dt (x > 0) (3.7.7) (bj ; j )1;m ; (; m+1 ) 0 to generalized functions and proved the representation for such a transform in [1], [3] and an inversion and a uniqueness theorem in [2], [5]. They established some Abelian theorems for such a distribum;0 in [6] and [4], tional transform and for more general distributional transforms with the kernel Hp;q respectively. See also Raj.K. Saxena, Koranne and Malgonde [1] in this connection. We also indicate that, though applications of the H -function (1.1.1) in statistics and other disciplines are well known (see Mathai and R.K. Saxena [2]), only one paper by Raina [2] was devoted to application of the H -transform concerning the problem of absolute moments of arbitrary order of a probability distribution function.
For Sections 3.2 and 3.3. The results presented in these sections belong to Rooney [6, Sections 2 and 5]. We only note that the Erdelyi{Kober type fractional integrals (3.3.1) and (3.3.2) were introduced by Kober [2] for = 1 and by Erdelyi [3] in the general case, and they gave the conditions for the boundedness of these operators in the space L1=r;r = Lr (R+ ) for 1 < r < 1. When = 2, the operators (3.3.1) and (3.3.2) are known as Erdelyi{Kober operators, and Sneddon [2] was the rst to name them in this way.
For Sections 3.4{3.6. The results of these sections were proved by the authors together with Shlapakov in Kilbas, Saigo and Shlapakov [1], and some of these assertions were indicated in Kilbas and Shlapakov [2] (see also the papers of Shlapakov [1] and Kilbas, Saigo and Shlapakov [2], [3]). Theorems 3.3 and 3.4 in Section 3.4 establish the integral representations (3.4.3) and (3.4.12) for the m;n in (1.1.1) on the spaces L;2. They, together with Theorem 3.5 in Section 3.5, play H -function Hp;q the main role in constructing L;2-theory for the H -transforms in Theorems 3.6 and 3.7 in Section 3.6. The obtained results generalize the corresponding results by Rooney [6, Lemmas 3.2, 3.3 and 4.1 and Theorem 4.1], being proved for the G-transform (3.1.2) (see also Section 5.1 in this connection). We also note that the statements presented in Sections 3.4{3.6 were independently obtained by Betancor and Jerez Diaz [1].
Chapter 4 H -TRANSFORM ON THE SPACE L;r In Chapter 3 we constructed so-called L;2 -theory of the H -transform (3.1.1), where we characterize the existence, the boundedness and representation properties of the transforms H on the space L;2 given in (3.1.3). The present chapter is devoted to extending the above results from r = 2 to any r = 1: Moreover, we shall deal with the study of properties such as the range and the invertibility of the H -transform on the space L;r with any 1 5 r < 1. The results will be di erent in nine cases: 1) a = = Re() = 0; 2) a = = 0; Re() < 0; 3) a = 0; > 0; 4) a = 0; < 0; 5) a1 > 0; a2 > 0; 6) a1 > 0; a2 = 0; 7) a1 = 0; a2 > 0; 8) a > 0; a1 > 0; a2 < 0; 9) a > 0; a1 < 0; a2 > 0: Here a , , , a1 and a2 are given in (1.1.7), (1.1.8), (1.1.10), (1.1.11) and (1.1.12), respectively. We shall also use the constants and de ned by (3.4.1) and (3.4.2), respectively.
4.1.
L;r -Theory of
the H -Transform When a = = 0 and Re() = 0
In this and the next sections, based on the existence of the transform H on the space L;2 which is guaranteed in Theorem 3.6 for some 2 R and a = = 0; Re() 5 0, we prove that such a transform can be extended to L;r for 1 < r < 1 such that H 2 [L;r ; L1;;s ] for a certain range of the value s. We also characterize the range of H on L;r in terms of the Erdelyi{Kober type fractional integral operators I0+; ; and I;;; given in (3.3.1) and (3.3.2) except for its isolated values 2 EH . The results will be di erent in the cases Re() = 0 and Re() 6= 0. In this section we consider the former case.
Theorem 4.1. Let a = = 0; Re() = 0 and < 1 ; < : Let 1 < r < 1. (a) The transform H de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;r ]. (b) If 1 < r 5 2; the transform H is one-to-one on L;r and there holds the equality
(3:1:5); namely;
MH f (s) = H(s) Mf (1 ; s) (Re(s) = 1 ; ):
(4.1.1)
H (L;r ) = L1;;r :
(4.1.2)
(c) If 2= EH ; then H is a one-to-one transform on L;r onto L1;;r ; i.e. (d) If f 2 L;r and g 2 L;r0 and r0 = r=(r ; 1); then the relation (3:6:1) holds: Z
0
1
f (x)
H g (x)dx =
Z
0
93
1
Hf
(x)g (x)dx:
(4.1.3)
94
Chapter 4.
H -Transform on the Space L
;r
(e) If f 2 L;r ; 2 C and h > 0; then H f is given by
Hf
(x)
= hx1;(+1)=h d x(+1)=h
Z
dx
# (;; h); (ai; i)1;p f (t)dt (bj ; j )1;q ; (; ; 1; h)
"
1 m;n+1 Hp+1;q+1 xt 0
(4.1.4)
for Re() > (1 ; )h ; 1; while
Hf
(x)
= ;hx1;(+1)=h d x(+1)=h dx
Z
(a ; ) 1 m+1;n i i 1;p; (;; h) Hp+1;q+1 xt 0 (; ; 1; h); (bj ; j )1;q "
#
f (t)dt
(4.1.5)
for Re() < (1 ; )h ; 1. Proof. Since < 1 ; < and (1 ; ) + Re() 5 0; then according to Theorem 3.6 the transform H is de ned on L;2 . We denote by H0(s) the function
H0(s) = ;sH(s);
(4.1.6)
where is de ned in (1.1.9). It follows from (1.2.9) that
H0( + it)
q
Y
j =1
jRe(bj );1=2
p
Y
i=1
1i =2;Re(ai ) (2 )c e;c e;Im()sign(t)=2
(4.1.7)
(jtj ! 1)
is uniformly in in any bounded interval of R. Therefore H0(s) is analytic in the strip < Re(s) < , and if < 1 5 2 < , then H0(s) is bounded in the strip 1 5 Re(s) 5 2 . Since a = = 0, then in accordance with (1.1.13) a1 = ;a2 = =2 = 0. Then from (4.1.6) and (3.4.14) we have
H0 ( + it) = H0( + it)
0 ; log + HH(( ++ itit))
"
0
#
1 Im( ) = H0 ( + it) t + O t2 = O 1t (jtj ! 1)
(4.1.8)
for < < . Thus H0 (s) belongs to the class A (see De nition 3.2) with (H0 ) = and (H0 ) = . Therefore by virtue of Theorem 3.1, there is a transform T 2 [L1;;r ] for 1 < r < 1 and < 1 ; < . When 1 < r 5 2, then T is a one-to-one transform on L1;;r and the relation MT f (s) = H0 (s) Mf (s) (Re(s) = 1 ; )
holds for f 2 L1;;r . Let
H 0 = W T R;
(4.1.9) (4.1.10)
4.1. L;r -Theory of the H -Transform When a = = 0 and Re() = 0
95
where W and R are given in (3.3.12) and (3.3.13). According to Lemma 3.1(ii) and Lemma 3.1(iii), R 2 [L;r ; L1;;r ], W 2 [L1;;r ] and hence H 0 2 [L;r ; L1;;r ] for < 1 ; < and 1 < r < 1, too. When < 1 ; < , 1 < r 5 2 and f 2 L;r , it follows from (4.1.10), (3.3.15), (4.1.9), (3.3.16) and (4.1.6) that MH 0f (s) = MW T Rf (s) = s MT Rf (s)
= s H0 (s) MRf (s) = s H0 (s) Mf (1 ; s)
= H(s) Mf (1 ; s)
(4.1.11)
for Re(s) = 1 ; . In particular, for f 2 L;2 Theorem 3.6(i), (3.1.5) and (4.1.11) imply the equality MH 0 f (s) = MH f (s) (Re(s) = 1 ; ):
(4.1.12)
Thus H 0f = H f for f 2 L;2 and therefore, if < 1 ; < , H = H 0 on L;2 by Theorem 3.6(iv). Since L;2 T L;r is dense in L;r (see Rooney [2, Lemma 2.2]), H can be extended to L;r and, if we denote it there by H again, H 2 [L;r ; L1;;r ]. This completes the proof of assertion (a) of the theorem. The property (b) is clear from the fact that the operator T above and the operators W and R are one-to-one and (4.1.1) follows from (4.1.11). Let us prove (c). Since R(L;r ) = L1;;r and W (L1;;r ) = L1;;r , then the onto map property H (L;r ) = L1;;r holds if and only if T (L1;;r ) = L1;;r . To prove this, it should be noted that the abscissas of the zeros of H(s) divide the interval ( ; ) into disjoint open intervals, where and thereafter H0 (s) in (4.1.6) is renamed H(s). Let ( 1; 1) be one such interval. Then the function 1=H(s) is analytic in 1 < Re(s) < 1 . In view of (4.1.7) we have q p Y Y 1 ai );1=2(2 );c ec eIm()sign(t)=2 (jtj ! 1): j1=2;Re(bj ) Re( i H( + it) j=1 i=1
So if we take 1 < 1 5 2 < 1, then 1=H(s) is bounded in the strip 1 5 Re(s) 5 2. The equality
1 0 ( + it) = ; H0 ( + it) H H2( + it)
implies by (4.1.7) and (4.1.8) that
1 0 ( + it) = O 1 (jtj ! 1) H t
for 1 < < 2 : Thus we have that 1=H 2 A with (1=H) = 1 and (1=H) = 1: Then for 1 < < 1 and 1 < r < 1 it follows from Theorem 3.1 that the transform T is one-to-one on L;r and T (L;r ) = L;r . But if 2= EH , then the value 1 ; does not coincide with the abscissa of any zero of H(s), and hence 1 ; lies in such ( 1; 1): Therefore H is a one-to-one transform on L;r and H (L;r ) = L1;;r . The assertion (c) of the theorem is thus proved.
96
Chapter 4.
H -Transform on the Space L
;r
Now we prove (4.1.3). If < 1 ; < , then by using the Holder inequality Z
b a
b
Z
f (x)g (x)dx 5
a
we have Z
0
1
H g (x)dx
f (x)
=
Z
0
1=p
!
jf (x)jpdx
Z
b
a
1=p0
!
jg(x)jp0dx
(4.1.13)
1 + 1 = 1; ;1 5 a < b 5 1 p p0
1 ;1=r 1 =r ; [x f (x)][x g (x)]dx
H
5 kf k;r kH gk1;;r0 5 K kf k;r kgk;r0 r1 + r10 = 1 ; where K is a bound for H 2 [L;r0 ; L1;;r0 ]: Hence the left-hand side of (4.1.3) represents a bounded bilinear functional on L;r L;r0 . Similarly it is proved that the right-hand side of (4.1.3) represents such a functional on L;r L;r0 . By virtue of Theorem 3.6(ii), if f 2 L;2 T and g 2 L;2 , (3.6.1) is also true. By Rooney [2, Lemma 2.2] L;r L;2 is dense in L;r and hence (3.6.1) is true for f 2 L;r and g 2 L;r0 with 1 < r < 1 and < 1 ; < . This completes the proof of the assertion (d) of the theorem. Finally we prove (e). If Re() > (1 ; )h ; 1, then the function 8 < t(+1)=h;1 if 0 < t < x; gx (t) = : (4.1.14) 0 if t > x belongs to L;s for 1 5 s < 1: When s = 2, we may apply Theorem 3.6(iii) for gx 2 L;2 and we have " # Z x (;; h); (a ; ) i i 1 ;p d m;n +1 H gx (y) = hy1;(+1)=h dy y(+1)=h 0 Hp+1;q+1 yt (b ; ) ; (; ; 1; h) j j 1;q
t(+1)=h;1dt
+1 t (;; h); (ai; i)1;p Hpm;n +1 ;q +1 dy 0 (bj ; j )1;q ; (; ; 1; h)
= hy 1;(+1)=h d
Z
"
xy
#
t(+1)=h;1dt
# (;; h); (ai; i)1;p (bj ; j )1;q ; (; ; 1; h) almost everywhere. For f 2 L;r with < 1 ; < and 1 < r < 1 and for the above gx 2 L;r0 , we have from the previous result (d) that
"
+1 = hx(+1)=h Hpm;n +1;q+1 xy
x
Z
0
t(+1)=h;1
Hf
(t)dt =
1
Z
0
Hf
(t)gx(t)dt =
1
Z
0
f (t)
H gx (t)dt
# (;; h); (ai; i )1;p f (t)dt: (bj ; j )1;q ; (; ; 1; h) From here, after di erentiation with respect to x; we arrive at (4.1.4). In the case Re() < (1 ; )h ; 1 the relation (4.1.5) is proved similarly if we use the function 8 < 0 if 0 < t < x; hx (t) = : (+1)=h;1 t if t > x
= hx(+1)=h
"
1 m;n+1 Hp+1;q+1 xt 0
Z
4.2. L;r -Theory of the H -Transform When a = = 0 and Re() < 0
97
instead of the function gx (t). Thus the theorem is proved.
4.2.
L;r -Theory of
the H -Transform When a = = 0 and Re() < 0
Now we consider the H -transform in the case a = = 0 and Re() < 0.
Theorem 4.2. Let a = = 0; Re() < 0 and < 1 ; < ; and let either m > 0 or
n > 0. Let 1 < r < 1. (a) The transform H de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform H is one-to-one on L;r and there holds the equality (4:1:1): (c) Let k > 0. If 2= EH ; then the transform H is one-to-one on L;r and there hold
H (L;r ) = I;;k;; =k (L ;;r )
(4.2.1)
H (L;r ) = I ; k; =k; (L ;;r )
(4.2.2)
1
;
for m > 0; and 0+;
1
1
for n > 0. If 2 EH ; H (L;r ) is a subset of the right-hand sides of (4:2:1) and (4:2:2) in the respective cases. (d) If f 2 L;r and g 2 L;s with 1 < r < 1; 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (4:1:3) holds. (e) If f 2 L;r ; 2 C and h > 0; then H f is given in (4:1:4) for Re() > (1 ; )h ; 1; while in (4:1:5) for Re() < (1 ; )h ; 1. Furthermore H f is given in (3:1:1); namely,
Hf
(x) =
Z
1 m;n Hp;q 0
"
(ai ; i)1;p # xt f (t)dt: (bj ; j )1;q
(4.2.3)
Proof. Since < 1 ; < , a = 0 and (1 ; ) + Re() = Re() < 0, then from
Theorem 3.6 the transform H is de ned on L;2 . If m > 0 or n > 0, then or is nite in view of (3.4.1) and (3.4.2). We set
3 2 s ; ; 1 ; k ; ( a ; ) ; ; i i 1;p 6 7 s7 k k H1(s) = s ; H(s) = Hmp+1+1;q;n+1 64 5 1 ; ; k ; k ; (bj; j )1;q ; k for m > 0, and
2 s ; ; 1 ; (a ; ) 3 ; ; 1 + ; i i 1;p 7 +1 6 k k s7 H2(s) = k ; s H(s) = Hm;n p+1;q+1 6 5 4 1 (bj ; j )1;q ; 1 ; k ; k ; k
(4.2.4)
(4.2.5)
98
Chapter 4.
H -Transform on the Space L
;r
for n > 0. We denote 1 ; 1; ae1 ; 1 ; 1 and 1 for H1 , and 2 ; 2; ae2 ; 2 ; 2 and 2 for H2 instead of that for H. Then we nd that 1 = max[ ; + kRe()] = ; 1 = ; ae1 = a = 0; 1 = = 0; 1 = ; 1 = 0; (4.2.6) 2 = ; 2 = min[ ; ; kRe()] = ; ae2 = a = 0; 2 = = 0; 2 = ; 2 = 0; and the exceptional sets EH 1 and EH 2 of H1 and H2 in De nition 3.4 coincide with EH for H. f and H f in Since 1 = 2 = 0, Theorem 4.1 guarantees the existence of two transforms H 1 2 [L;r ; L1;;r ] for m > 0 and for n > 0, respectively. Further, if f 2 L;r with 1 < r 5 2, then by (4.1.1)
f f (s) = H (s) Mf (1 ; s) MH (Re(s) = 1 ; ; i = 1; 2): i i
We set
H
for m > 0, and
H
f = I;;;k;; =k H 1
(4.2.8)
; f = I0+; k; =k;1 H 2
(4.2.9)
1
2
(4.2.7)
for n > 0: Let (i) m > 0 or (ii) n > 0. For 1 5 r 5 1, s = r, 1=s > 1=r + Re() Theorem 3.2(b) ; and Theorem 3.2(a) imply that I;;;k;; =k 2 [L1;;r ; L1;;s ] for < 1 ; and I0+; k; =k;1 2 [L1;;r ; L1;;s ] for > 1 ; , respectively. Therefore, if < 1 ; < and 1 < r < 1; we f 2 [L have H i ;r ; L1;;s ] (i = 1; 2) for all s = r with 1=s > 1=r + Re(). Since from Theorem ; 3.2(a),(b) I;;;k;; =k and I0+; k; =k;1 are one-to-one on L1;;r and then by Theorem 4.1(b),(c), if 2= EH ; or if 1 < r 5 2, H i (i = 1; 2) are one-to-one on L;r . For f 2 L;r with < 1 ; < and 1 < r 5 2, (4.2.8), (3.3.7), (4.2.7), (4.2.4) and (4.2.9), (3.3.6), (4.2.7), (4.2.5) imply s ; ; k f f MH MH 1f (s) = MI;;;k;; =k H f ( s ) = 1 f (s) 1 ; s ;k ; ; s ;k = s ; H1(s) Mf (1 ; s) ; k ; = H(s) Mf (1 ; s) (Re(s) = 1 ; ) (4.2.10) for the case (i) and ; s ; k MH ; f f (s) f MH 2 f (s) = MI0+; 2 k; =k;1 H 2 f (s) = ; s ; k ;
4.2. L;r -Theory of the H -Transform When a = = 0 and Re() < 0
99
s ; ; = ; ks H2 (s) Mf (1 ; s) ; k ; = H(s) Mf (1 ; s) (Re(s) = 1 ; ) (4.2.11) for the case (ii). In particular, for f 2 L;2 with < 1 ; < there hold MH i f (s) = MH f (s) (Re(s) = 1 ; ; i = 1; 2) for the cases (i) and (ii), respectively. Hence, H = H i on L;2 (i = 1; 2). Thus H can be extended to L;r by de ning it as H 1 for (i) and by H 2 for (ii), and H 2 [L;r ; L1;;s ] for all s = r such that 1=s > 1=r + Re(). This completes the proof of (a). f (i = 1; 2) are one-to-one by Theorem The statement (b) follows from the fact that H i ; 4.1(b) and that I;;;k;; =k and I0+; are one-to-one, too. k; =k;1 Now we proceed to prove (c). The one-to-one property can be obtained similar to (b). f (L If the conditions of our theorem hold, then due to Theorem 4.1 H i ;r ) L1;;r , and if f 2= EH , then H i(L;r ) = L1;;r (i = 1; 2): Therefore, it follows from (4.2.6), (4.2.10) and (4.2.9), (4.2.11) the following: For (i), H (L;r ) I;;;k;; =k (L1;;r ) and, if further 2= EH , H (L;r ) = I;;;k;; =k (L1;;r ); i.e. (4.2.1) holds. ; ; For (ii), H (L;r ) I0+; k; =k;1(L1;;r ) and, if further 2= EH , H (L;r ) = I0+;k; =k;1 (L1;;r ); i.e. (4.2.2) holds. These prove (c). To establish (4.1.3) for f 2 L;r and g 2 L;s with 1 < r < 1; 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(), we show as in the proof of Theorem 4.1(d) that both sides of (4.1.3) are bounded bilinear functionals on L;r L;s . From the assumption we have r0 = s (1=r + 1=r0 = 1) and 1=r0 > 1=s + Re(), and hence H 2 [L;s ; L1;;r0 ] by assertion (a). Applying Holder's inequality (4.1.13), we have
1
Z
0
H g (x)dx
f (x)
=
Z
0
1 ;1=r x f (x)x1=r;
H g (x)dx
5 kf k;r kH gk1;;r0 5 K kf k;r kgk;s; where K is a bound for H 2 [L;s ; L1;;r0 ]. Hence the left-hand side of (4.1.3) represents a bounded bilinear functional on L;r L;s . Similarly it can be proved that the right-hand side of (4.1.3) represents such a functional on L;r L;s . Thus the assertion (d) is obtained. Lastly we prove (e). Let f 2 L;r with 1 < r < 1. Then the representations (4.1.4) and (4.1.5), when Re() > (1 ; )h ; 1 and Re() < (1 ; )h ; 1, respectively, are deduced from Theorem 3.6(iii) in the same way as was done in the proof of Theorem 4.1. Now denote e +1 for the function Hpm;n +1;q +1 (t) in (4.1.4) instead of for the H -function (1.1.1). By (1.1.10) e = ; 1, then the assumption Re() < 0 implies Re(e) < ;1. Since < 1 ; < , it follows +1 from Theorem 1.2 that if Re() > (1 ; )h ; 1, then Hpm;n +1;q +1 (t) in (4.1.4) is continuously di erentiable with respect to t on R+ . Therefore we can di erentiate under the integral sign in (4.1.4). Applying the relations (2.2.7) and (2.1.1), we have " # Z 1 (;; h); (a ; ) i i 1;p d m;n +1 H f (x) = hx1;(+1)=h dx x(+1)=h 0 Hp+1;q+1 xt (b ; ) ; (; ; 1; h) f (t)dt j j 1;q
100
Chapter 4.
= hx
;
1 ( +1)
=h
Z 0
H -Transform on the Space L
;r
1 1;(+1)=h t
" (;; h); (a ; ) i i 1;p d m;n +1 (+1)=h Hp+1;q+1 xt d(xt) (xt) (bj ; j )1;q ; (; ; 1; h) " # Z 1 (; ; 1; h); (a ; ) i i 1;p m;n +1 = Hp+1;q+1 xt f (t)dt 0 (bj ; j )1;q ; (; ; 1; h) " # Z 1 (a ; ) i i 1;p m;n = Hp;q xt f (t)dt 0 (bj ; j )1;q (
#)
f (t)dt
(4.2.12)
and we obtain (4.2.3), provided that the last integral in (4.2.12) exists. The existence of this integral is proved on the basis of (3.4.13) similarly to those in Theorem 3.7. Indeed, we choose
1 and 2 so that < 1 < 1 ; < 2 < . According to (3.4.13) there are constants A1 and A2 such that for almost all t > 0, the inequalities
m;n (t) 5 A t; i (i = 1; 2) Hp;q i
hold. Therefore, using the Holder inequality (4.1.13), we have Z
1 m;n+1 Hp+1;q +1 (xt)f (t) dt 0
5
1=r r 0 1 m;n+1 1=r ; kf k;r Hp+1;q +1 (xt)t dt 0
Z
2
5 4A1x; 1
=x
Z 1 0
tr ;; 1 );1 dt 0 (1
!1
=r0
+ A2 x; 2
Z
03
1 r0 (1; ; );1 !1=r 2 t dt 5 kf k;r 1=x
5 Cx;1 < 1; where
C = (A1[r0(1 ; ; 1)];1=r0 + A2 [r0( 2 + ; 1)];1=r0 )kf k;r : The proof for the case Re() < (1 ; )h ; 1 is similar. Thus the theorem is proved.
4.3.
L;r -Theory
of the H -Transform When a = 0; > 0
In this and the next sections we prove that, if a = 0 and 6= 0, the transform H de ned on L;2 can be extended to L;r such as H 2 [L;r ; L1;;s ] for some range of values s. Then we characterize the range H on L;r except for its isolated values 2 EH in terms of the modi ed Hankel transform H k; and the elementary transform M given in (3.3.4) and (3.3.11). The result will be di erent in the cases > 0 and < 0. In this section we consider the case > 0.
Theorem 4.3. Let a = 0; m > 0; > 0; < 1 ; < ; 1 < r < 1 and (1 ; ) +
Re() 5 1=2 ; (r); where (r) is de ned in (3:3:9):
4.3. L;r -Theory of the H -Transform When a = 0; > 0
101
(a) The transform H de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; (1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H is one-to-one on L;r and there holds the equality
(4:1:1):
(c) If 2= EH ; then the transform H is one-to-one on L;r . If we set = ; ; ; 1; then Re( ) > ;1 and there holds
H (L
) = M=+1=2 H ; L ;1=2;Re()=;r : (4.3.1) When 2 EH ; H (L;r ) is a subset of the right-hand side of (4:3:1): (d) If f 2 L;r and g 2 L;s 1 < s < 1; 1=r + 1=s = 1 and (1 ; ) + Re() 5 1=2 ; max[ (r); (s)]; then the relation (4:1:3) holds. (e) If f 2 L;r ; 2 C ; h > 0 and (1 ; )+Re() 5 1=2 ; (r); then H f is given in (4:1:4) for Re() > (1 ; )h ; 1; while in (4:1:5) for Re() < (1 ; )h ; 1. If (1 ; ) + Re() < 0; H f is given in (4.2.3). Proof. Since (r) = 1=2, we have (1 ; ) + Re() 5 0 by assumption, and hence from Theorem 3.6 the transform H is de ned on L;2 . The conditions > 0, < 1 ; and the relation (1 ; ) + Re() 5 0 imply = 1 + Re()= and < ;Re()=. Since a = 0, then by (1.1.11){(1.1.13) (4.3.2) a1 = ;a2 = > 0: 2 We denote by H3 (s) the function (4.3.3) H3(s) = s;1(a1)(1;s)+ ;[;;[a+(1a1;(s ;;1 s;)] )] H(1 ; s): 1 As already known, the function H(1 ; s) is analytic in the strip 1 ; < Re(s) < 1 ; and the function ;[; + a1(s ; 1 ; )] is analytic in the half-plane 2Re() : ) = +1+ Re(s) > + 1 + Re( a1 Since < ;Re()=, 1 ; > + 1 + 2Re()=, and, if we take 2Re( ) 1 = max 1 ; ; + 1 + ; 1 = 1 ; ; then 1 < 1 and H3 (s) is analytic in the strip 1 < Re(s) < 1. Setting s = + it and a complex constant k = c + id, in accordance with (1.2.2) we have the asymptotic behavior ;r
p
;(s + k) = ;[c + + i(d + t)] 2 e;c; jtjc+;1=2 e;jtj=2;dsign(t)=2
(4.3.4)
(jtj ! 1): Then by taking a = 0, = 2a1 and (1.2.9) into account from (4.3.4) we have
H3( + it) (2)
c
= 6= 0
e;c
q p Y Y jRe(bj );1=2 1i =2;Re(ai) e[Im(+)]sign(t)=2 j =1 i=1
(4.3.5)
102
Chapter 4.
H -Transform on the Space L
;r
as jtj ! 1. Therefore, for 1 < 1 5 2 < 1, H3 (s) is bounded in 1 5 Re(s) 5 2 . If 1 < < 1, then (
H0 ( + it) = H3( + it) 3
+a1
log ; log a1 + a1 [a1(s ; ; 1) ; ]
0 (1 ; s) [a1(1 ; ; s)] ; H H(1 ; s)
)
(4.3.6)
:
Using (3.4.14) with a = 0, (4.3.2) and (4.3.5), and applying the estimate (3.4.17) for the psi function (z ), we have from (4.3.6), as jtj ! 1, H03( + it) 8 3 2 > ( ; ; 1) ; ; 1 > < a 6 1 2 775 = H3 ( + it) >log ; 2a1 log a1 + a1 64log(ia1t) + ia t > :
2 a1 (1 ; ; ) ; 6 6 +a1 4log(;ia1t) ; ia1t
;
1
13 2 775
)
; ) + O 1 log + a1 log(;it) + a1 log(it) ; + (1 it t2
= O t12 :
(4.3.7)
So H3 2 A with (H3 ) = 1 and (H3) = 1. Hence due to Theorem 3.1 there is a transform T3 corresponding to H3 with 1 < r < 1 and 1 < < 1, and if 1 < r 5 2, then T3 is one-to-one on L;r into itself and (MT3f )(s) = H3 (s)(Mf )(s) (Re(s) = ): (4.3.8) In particular, if and r satisfy the hypothesis of this theorem, it is directly veri ed that 1 < < 1 and hence the relation (4.3.8) is true. Indeed, from < ;Re()= we nd 2Re() < ; Re() + 1 + 2Re() 5 +1+ by virtue of (1 ; ) + Re() 5 0. Together with this and < 1 ; < , the relation 1 < < 1 follows. Let = ; ; ; 1 and let H 3 be the operator H 3 = W M=+1=2H ; M=+1=2T3 (4.3.9) composed by the operators W in (3.3.12) and M in (3.3.11), the modi ed Hankel transform (3.3.4) and the transform T3 above, where < ;Re()= so that Re( ) > ;1. For 1 < r < 1 and 1 < < 1, Lemma 3.1(i) implies that M=+1=2 T3 maps L;r boundedly into L ;Re()=;1=2;r . Since < 1 ; and (1 ; ) + Re() 5 1=2 ; (r), we have 1 < ; ; Re() + 1 = Re( ) + 3 : Re( ) ; 1 +
(r ) 5 ; 2 2 2
4.3. L;r -Theory of the H -Transform When a = 0; > 0
103
Hence Theorem 3.2(d), and Lemma 3.1(i),(ii) again yield H 3 2 [L;r ; L1;;s ] for all s = r such that ;1 ;1 1 1 Re( ) 0 (4.3.10) s = ; ; 1 + 2 = 2 ; (1 ; ) ; Re() : In particular, H 3 2 [L;r ; L1;;r ], since r can be taken instead of s due to the fact that
(r) = 1=r0. If f 2 L;r with 1 < r 5 2, then applying (3.3.15), (3.3.14), (3.3.10), (3.3.14), (4.3.8) and (4.3.3) and using the relation = ; ; ; 1, we have for Re(s) = 1 ;
MH 3f (s) = MW M=+1=2 H ; M=+1=2 T3f (s)
= s MM=+1=2 H ; M=+1=2 T3f (s) = s MH ; M=+1=2 T3 f s + + 21 + s + + 1 s+ ; 1 2 MM=+1=2T3 f 1 ; s ; ; = s 2 2 ; ; s2; + 1 (s ; ) s+ ; 2 MT3 f (1 ; s) = s 2 ; ; ; (s2+ ) = s (a1);;s ;[;;[a;1 (as;(s +)] )] H3 (1 ; s) Mf (1 ; s) 1
= H(s) Mf (1 ; s) :
(4.3.11)
In particular, if we take r = 2 and f 2 L;2 , (4.3.11) and Theorem 3.6(i) imply (MH 3f ) (s) = (MH f ) (s) for Re(s) = 1 ; . Therefore H 3 f = H f and hence H 3 = H on L;2 . Thus, for all and r satisfying the hypotheses of this theorem, H can be extended from L;2 to L;r if we de ne it by H 3 given in (4.3.9) as an operator on [L;r ; L1;;s ]. This completes the proof of the statement (a) of the theorem. The assertion (b) is already obtained. Now we prove (c). By Theorem 3.2(d) and the properties (i) and (ii) in Lemma 3.1, we nd that H; , M and W are one-to-one in the corresponding spaces. Therefore, H 3 is a one-to-one transform if and only if T3 is one-to-one. Further, we have that and that
H (L
;r
) W M=+1=2 H ; M=+1=2 (L;r );
H (L
;r
) = W M=+1=2 H ; M=+1=2 (L;r );
(4.3.12) (4.3.13)
if and only if T3 (L;r ) = L;r . The relation (4.3.13) can be written as
H (L
;r
) = M=+1=2 H ; L ;1=2;Re()=;r
(4.3.14)
104
Chapter 4.
H -Transform on the Space L
;r
by virtue of Theorem 3.2, Lemmas 3.1, 3.2, and the fact such a range does not depend on a non-zero constant multiplier. The abscissas of zero of H3 divide the interval ( 1; 1) into disjoint open subintervals. If we take ( 0 ; 0) as such a subinterval, then 1=H3 2 A with (1=H3 ) = 0 ; (1=H3) = 0: For 1 < r < 1 and 0 < < 0 by Theorem 3.1 we nd that H 3 is one-to-one transform on L;r and H 3 (L;r ) = L;r . If r and satisfy the hypotheses of this theorem and if 2= EH , then does not coincide with any abscissa of zeros of H3 (s). It follows from De nition 3.4 that 1 ; is not on the abscissa of any zero of H(s) and therefore is not on the abscissa of any zero of H3(1 ; s). We also have that is not a zero of 1=;[a1(1 ; s ; )]; because 1 ; > . So if 2= EH , then H 3 is a one-to-one transform on L;r , and H 3 (L;r ) = L;r . Therefore the statement (c) already follows from (4.3.12) and (4.3.13). The proofs of assertions (d) and (e) of this theorem are carried out in the same way as they were done in the proofs of the statements (d) and (e) in Theorem 4.2. This completes the proof of the theorem.
4.4.
L;r -Theory
of the H -Transform When a = 0; < 0
Now we consider the H -transform with a = 0 and < 0. Our arguments are based on reducing the case above to the one investigated in Theorem 4.3 for > 0.
Theorem 4.4. Let a = 0; < 0; n > 0; < 1 ; < ; 1 < r < 1 and (1 ; ) + Re() 5 1=2 ; (r): (a) The transform H de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; (1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H is one-to-one on L;r and there holds the equality
(4:1:1):
(c) If 2= EH ; then the transform H is one-to-one on L;r . If we set = ; ; ; 1; then Re( ) > ;1 and the relation
H (L ) = M +1 2H L ;1 2;Re( ) holds. When 2 EH ; H (L ) is a subset of the set on the right-hand side of (4:4:1): ;r
=
=
;
=
= ;r
(4.4.1)
;r
(d) If f 2 L;r and g 2 L;s with 1 < s < 1; 1=r +1=s = 1 and (1 ; )+Re() 5 1=2 ;
max[ (r); (s)]; then the relation (4:1:3) holds. (e) If f 2 L;r ; 2 C ; h > 0 and (1 ; )+Re() 5 1=2 ; (r); then H f is given in (4:1:4) for Re() > (1 ; )h ; 1; while in (4:1:5) for Re() < (1 ; )h ; 1. If (1 ; ) + Re() < 0; then H f is given in (4.2.3). Proof. By similar arguments to that in the proof of Theorem 4.3 we nd that the transform H is de ned on L;2 . Let H 0 = RH R, where R is given in (3.3.13). Then according to Lemma 3.1(iii), H 0 2 [L1;;2 ; L;2 ]. If f 2 L1;;2 , then using (3.3.16) and (3.1.5), we have
MH 0 f (s) = MRH Rf (s) = MH Rf (1 ; s) = H(1 ; s) MRf (s)
= H(1 ; s) Mf (1 ; s) = H0(s) Mf (1 ; s) (Re(s) = );
(4.4.2)
4.4. L;r -Theory of the H -Transform When a = 0; < 0
105
where
H0(s) = H(1 ; s) = Hn;m q;p
"
(1 ; bj ; j ; j )1;q # s : (1 ; ai ; i ; i)1;p
(4.4.3)
We denote 0 ; 0; a0; 0 ; 0 and 0 for H0 instead of that for H. Then taking (3.4.1), (3.4.2) and (1.1.7){(1.1.10) into account, we have 0 = 1 ; ; 0 = 1 ; ; a0 = a = 0; 0 = 1=; 0 = ;; 0 = + :
(4.4.4)
If we denote 1 ; by 0 , then from (4.4.4) and the hypotheses of this theorem we have 0 < 1 ; 0 < 0 and 0 (1 ; 0 ) + Re(0 ) = (1 ; ) + Re() 5 21 ; (r): Since a0 = 0 and 0 > 0, we can apply Theorem 4.3(a) to obtain that H 0 can be extended from L0 ;2 = L1;;2 to L0 ;r = L1;;r as an element of [L0 ;r ; L1;0 ;s ] = [L1;;r ; L;s ] for all s with r 5 s < 1 such that s0
;1 ;1 1 1 = 2 ; 0(1 ; 0 ) ; Re(0) = 2 ; (1 ; ) ; Re() :
Let us notice that
H f = RH 0Rf
(f 2 L;2 ):
(4.4.5)
In accordance with Lemma 3.1(iii), R(L;r ) = L1;;r = L0 ;r :
(4.4.6)
So we can extend H from L;2 to L;r if it is de ned by (4.4.5), and we obtain the boundedness of the operator H , which establishes the statement (a). The one-to-one property for 1 < r 5 2 is already found, and the equality (4.1.1) is seen by
MH f (s) = MRH 0 Rf (s) = MH 0Rf (1 ; s) = H0 (1 ; s) MRf (s)
= H0 (1 ; s) Mf (1 ; s) = H(s) Mf (1 ; s) (Re(s) = 1 ; );
which proves (b). That 2= EH is equivalent to 0 2= EH 0 implies the one-to-one property by Theorem 4.3(c). To prove (4.4.1) we note that from (4.4.5),
H (L;r ) = RH 0R (L;r ) = L ;s :
0
Then using (4.4.6) and (4.3.1) with being replaced by 0 = + , by 0 and by 0 = ;, while 0 = = ;0 0 ; 0 ; 1 = ; ; ; 1; and applying the relations in
106
Chapter 4.
H -Transform on the Space L
;r
(3.3.21) and (3.3.18), and again (4.4.6) we have
H (L;r ) = RH 0R (L;r ) = RH 0 (L1;;r )
= RM0 =0 +1=2 H 0 ;0 (L1=2; ;Re(0 )=0 ;r )
= RM;=;1=2 H ;; (L3=2; +Re()=;r )
= M=+1=2RH ;; (L3=2; +Re()=;r )
= M=+1=2H ; R (L3=2; +Re()=;r ) = M=+1=2H ; R (L ;1=2;Re()=;r ): Thus (4.4.1) is proved. The assertions (d) and (e) can be established in the same way as in the statements (d) and (e) of Theorem 4.2, which completes the proof of the theorem. To conclude this section we give useful statements followed from Theorems 4.1{4.4. Corollary 4.4.1.
hold: (a) (b) (c)
Let 1 < r < 1; < ; a = 0 and let one of the following conditions
> 0; < 1 21 ; Re() ; (r) ;
1 1 < 0; > 2 ; Re() ; (r) ; = 0; Re() 5 0;
where (r) is given in (3:3:9). Then the transform H can be de ned on L;r with < 1; < . Proof. Let a = 0; 6= 0: Then by Theorems 4.3 and 4.4 the condition (4.4.7) (1 ; ) + Re() 5 21 ; (r) must be satis ed together with < 1 ; < in order that the transform H can be de ned on L;r . If > 0, the assumption of (a) and < yield the existence of a number such that 1 1 ; Re() ; (r) ; 1 ; < ; <1; 5 2 which show the requirement. Similarly, for the case (b) we can deduce the existence of of the form 1 1 ; Re() ; (r) 5 1 ; < ; < 1 ; : 2 When a = = 0 and Re() 5 0, by Theorems 4.1 and 4.2 the transform H can be de ned on L;r . This completes the proof.
4.5. L;r -Theory of the H -Transform When a > 0
107
Remark 4.1. For r = 2; (r) = 1=2 and hence the cases (e), (f) and (g) of Corollary
3.6.1 follow from Corollary 4.4.1.
4.5.
L;r -Theory of
the H -Transform When a > 0
When a > 0 and < 1 ; < , Theorems 3.6 and 3.7 guarantee the existence of the H -transform on L;2 which is given in (3.1.1). Now let us prove that it can be extended to L;r for any 1 5 r 5 1. To do so we rst state a preliminary result due to Rooney [6, Lemma 5.1].
Lemma 4.1. (a) Suppose f 2 L;r and k 2 L;q , where 1 5 r 5 1; 1 5 q 5 1 and 1=r + 1=q = 1. Then the transform Z (4.5.1) K f (x) = 01 k xt f (t) dtt exists for almost all x 2 R+ and K 2 [L;r ; L;s ]; where 1=s = 1=r + 1=q ; 1. If; in addition; r 5 2; q 5 2 and s 5 2; then the Mellin convolution relation MK f ( + it) = Mk ( + it) Mf ( + it) (4.5.2) holds. (b) Suppose f 2 L;r and k 2 L1;;q ; where 1 5 r 5 1; 1 5 q 5 1 and 1=r + 1=q = 1. Then the transform Z T f (x) = 1 k(xt)f (t)dt (4.5.3) 0
exists for almost all x 2 R+ ; and T 2 [L;r ; L1;;s ]; where 1=s = 1=r +1=q ; 1. If, in addition, r 5 2; q 5 2 and s 5 2; then the modi ed Mellin convolution relation MT f (1 ; + it) = Mk (1 ; + it) Mf ( ; it) (4.5.4) holds. The next theorem presents the L;r -theory of the H -transform with a > 0 in L;r -spaces for any 2 C and 1 5 r 5 1:
Theorem 4.5. Let a > 0; < 1 ; < and 1 5 r 5 s 5 1: (a) The transform H de ned on L; can be extended to L;r as an element of [L;r ; L ;;s ].
When 1 5 r 5 2; H is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s0 with 1=s + 1=s0 = 1; then the relation (4:1:3) holds. Proof. It follows from Theorem 3.6 that the H -transform is de ned on L;2 , and by Theorem 3.7 it is given in (3.1.1). De ne a number Q by the equality 1=Q = 1=s ; 1=r + 1. Then 1 5 Q 5 1, and 1=r + 1=Q = 1: We choose 1 and 2 so that < 1 < 1 ; < 2 < . By the relation (3.4.13) in Theorem 3.4 there are constants A1 and A2 such that m;n ; i (i = 1; 2) Hp;q (t) 5 Ai t 2
1
108
Chapter 4.
H -Transform on the Space L
;r
hold for t 2 R+ . Using this, we have Z 1 Z 1 Z 1 Q Q dx dx 1; 1; m;n m;n (x) Q dx m;n Hp;q (x) x = x Hp;q (x) x + x1; Hp;q x x 0 1 0 Z 1
5
0
x(1;; 1 )Q;1dx +
1
Z 1
x(1;; 2 )Q;1dx
= (1 ; 1; )Q + ( + 1 ; 1)Q < 1: 1 2 m;n 2 L1;;Q . Now we set Therefore Hp;q
Hf
1
(x) =
Z
1 m;n Hp;q (xt)f (t)dt: 0
(4.5.5)
By Lemma 4.1(b), H 1 2 [L;r ; L1;;s ]. But H 1 = H on L;2 . So we can extend H from L;2 to L;r if we de ne it by (4.5.5), and H 2 [L;r ; L1;;s ]. In particular, if s = r, H 2 [L;r ; L1;;r ]. Now let 1 5 r 5 2. From (4.5.4), (3.4.12) and Titchmarsh [3, Theorem 29], we obtain the relation for f 2 L;r MH f (s) = Hm;n p;q (s) Mf (1 ; s) (Re(s) = 1 ; );
(4.5.6)
where Hm;n p;q (s) is given in (1.1.2). Since the poles of the gamma function are isolated (see Erdelyi, Magunus, Oberhettiger and Tricomi [1, Section 1.1]), the zeros of the function Hm;n p;q (s) are isolated, too. Therefore, if H f = 0 and Im(s) = t, then (Mf )( ; it) = 0 almost everywhere. Hence for 1 5 r 5 2, H is a one-to-one transform from L;r onto L1;;s . The assertion (a) of the theorem is proved. To prove (4.1.3) for f 2 L;r and g 2 L;s0 with 1=s + 1=s0 = 1 we show that both sides of (4.1.3) are bounded bilinear functionals on L;r L;s0 . By the assumption r 5 s we have s0 5 r0 and H 2 [L;s0 ; L1;;r0 ]. Applying the Holder inequality (4.1.13), we have Z
1
0
H g (x)dx
f (x)
=
Z 0
1 ;1=r x f (x)x1;;1=r0
H g (x)dx
5 kf k;r kH gk1;;r0 5 K kf k;r kgk;s0 ;
where K is a bound for H 2 [L;s0 ; L1;;r0 ]. Hence the left-hand side of (4.1.3) is a bounded bilinear functional on L;r L;s0 . Similarly it is proved that the right-hand side of (4.1.3) is a bounded bilinear functional on L;r L;s0 . This completes the proof of Theorem 4.5.
4.6. Boundedness and Range of the H -Transform When a > 0 and a > 0 1
2
In this and the next sections we consider the boundedness and range of the H -transform in the cases when a > 0 and a1 = 0 or a2 = 0. We give conditions for the transform H to be one-to-one on L;r and to characterize its range on L;r except for its isolated values 2 EH , in terms of the Erdelyi{Kober type fractional integration operators I0+; ; , I;;; , the modi ed Laplace transform Lk; and the operator W given in (3.3.1){(3.3.3) and (3.3.12). The results will be di erent depending on combinations of the signs of a1 and a2 . In this section
4.6. Boundedness and Range of the H -Transform When a1 > 0 and a2 > 0
109
we consider the case when a1 > 0 and a2 > 0 and hence a > 0 by (1.1.13).
Theorem 4.6. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; < and ! = + a1 ; a2 +1 and let 1 < r < 1: (a) If 2= EH ; or if 1 5 r 5 2; then the transform H is one-to-one on L;r . (b) If Re(!) = 0 and 2= EH ; then
H (L;r ) =
La1 ; La2 ;1; ;!=a2 (L1;;r ): (4.6.1) When 2 EH ; H (L;r ) is a subset of the right-hand side of (4:6:1): (c) If Re(!) < 0 and 2= EH ; then H (L;r ) = I;;;1!=a1;;a1 La1 ; La2 ;1; (L1;;r ): (4.6.2) When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.6.2). Proof. We rst consider the case Re(!) = 0. We de ne H4(s) by )a1 (s; );1 (a )a2 ( ;s)+!;1 ( a (4.6.3) H4(s) = ;[a1 (s ; )];[a2( ; s) + !] ;s H(s): 1 2 Since < 1 ; < , the function H4(s) is analytic in the strip < Re(s) < . According to (1.2.9) and (4.3.4) we have the estimate, as jtj ! 1, H4( + it) (a1)a1(; );1(a2)a2( ;)+Re(!);1 21 (a1jtj)a1( ;)+1=2 q
Y (ajtj)a2(; );Re(!)+1=2e+Re()+1e[ajtj+Im(!)sign(t)]=2 Re(bj );1=2 2
j =1
j
p Y 1i =2;Re(ai) (2 )c e;;Re();c jtj+Re()e;[a jtj+Im()sign(t)]=2 i=1
q p Y Y jRe(bj );1=2 1i =2;Re(ai)(2 )c;1 (a1a2);1=2e;c +1 eIm(!;)sign(t)=2 j =1 i=1
(4.6.4)
uniformly in on any bounded interval of R, where and c are given in (1.1.14) and (1.1.15). Further, in accordance with (3.4.17) and (3.4.14)
H0 ( + it) = H4( + it)
(
4
a1 log a1 ; a2 log a2 ; a1 [a1( + it ; )]
0 ( + it) ) H [a ( ; ; it) + ! ] ; log +
+a 2
H( + it)
2
(
= H4 ( + it) a1 log a1 ; a2 log a2 ; a1 log(ia1t) + a1 ( ;ia )t ; 1=2
! ; 1=2 ; log +a2 log(;ia2 t) ; a2 ( ; ia) + t +
2
log + a log(it) ; a log(;it) + Re() + 1
1
2
it
)
+ O t12
110
Chapter 4.
= O t12
H -Transform on the Space L
;r
(jtj ! 1):
(4.6.5)
So H4 2 A with (H4 ) = and (H4 ) = , and Theorem 3.1 implies that there is a transform T4 2 [L;r ] for 1 < r < 1 and < < so that, if 1 < r 5 2, the relation (MT4f )(s) = H4(s)(Mf )(s) (Re(s) = )
(4.6.6)
H 4 = W La ; La ;1; ;!=a T4R;
(4.6.7)
holds. Let 1
2
2
where W and R are de ned in (3.3.12) and (3.3.13). Then it follows from Lemma 3.1(ii),(iii) and Theorem 3.2(c) that if 1 < r 5 s < 1 and < 1 ; < , then H 4 2 [L;r ; L1;;s ]. For f 2 L;2 ; applying (4.6.7), (3.3.15), (3.3.8), (4.6.6) and (3.3.16), and noting that Re(! ) > 0, we have for Re(s) = 1 ;
MH 4 f (s) = MW La1 ; La2 ;1; ;!=a2 T4Rf (s) = s ;[a1a(1s(s;; );)]1 MLa2 ;1; ;!=a2 T4Rf (1 ; s) (a1 ) ; !=a2)]g MT Rf (s) = s ;[a1a(1s(s;; );)]1 ;fa2 [1 a;2 [1s;;s;(1(1;; ; !=a 4 )];1 2 (a1 ) (a2) ) + ! ] H (s)MRf (s) = s ;[a1a(1s(s;; );)]1 ;[a2 (a 2 ( ;;ss)+ 4 !;1 (a1 ) (a2)
= H(s) Mf (1 ; s):
(4.6.8)
So we obtain that, if f 2 L;2 , MH 4f (s) = MH f (s) with Re(s) = 1 ; . Hence H 4 = H on L;2 and H can be extended from L;2 to L;r if we de ne it by (4.6.7). The operator R is a one-to-one transform of L;r onto L1;;r by Lemma 3.1(iii), and La1 ; and La2 ;1; ;!=a2 are also one-to-one by Theorem 3.2(c). Therefore H 4 2 [L;r ; L1;;s ] is one-to-one if and only if T4 is one-to-one. Since T4 2 [L1;;r ], we have the imbedding
H (L;r )
W La1 ; La2 ;1; ;!=a2 (L1;;r ) = La1; La2 ;1; ;!=a2 (L1;;r )
for < 1 ; < and 1 < r < 1 (here we take into account (3.3.20) and the independence of the range on a non-zero constant milptiplier). Moreover, the equality (4.6.1) holds if and only if T4(L1;;r ) = L1;;r . According to Theorem 3.1, T4 is one-to-one on L1;;r and T4(L1;;r ) = L1;;r if and only if 1=H4 2 A and (1=H4) < 1 ; < (1=H4 ). It is proved similarly, as was done in the proof of Theorem 4.3 that, if 2= EH , these conditions are satis ed. This completes the proof of the theorem for Re(! ) = 0: Now we assume Re(! ) < 0 and denote by H5 (s) the function )a1 (s; );1 (a)a2 ( ;s);1 ;[a (s ; ) ; ! ] ( a ;s H(s); H5(s) = 1 ;2[a(s2 ; )];[a( ;1 s)] 1 2
(4.6.9)
4.6. Boundedness and Range of the H -Transform When a1 > 0 and a2 > 0
111
which is analytic in the strip < Re(s) < . Similar arguments to (4.6.4) and (4.6.5) show that the estimates
H5( + it)
q p Y Re(bj );1=2 Y 1=2;Re(ai)
j =1
j
i
i=1
(2)c;1(a1);Re(!);1=2(a2);1=2e1;c eIm(!;)sign(t)=2 and
(
H0 ( + it) = H5( + it) 5
;2a 1
(4.6.10)
a1 log a1 ; a2 log a2 + a1 [a1( + it ; ) ; ! ] 0( + it) ) H [a ( ; ; it)] ; log +
[a( + it ; )] + a 1
2
H( + it)
2
(4.6.11) = O t12 (jtj ! 1) hold uniformly in on any bounded interval of R. So H5 2 A with (H5 ) = and (H5 ) = . By Theorem 3.1 there is a transform T5 2 [L;r ] for 1 < r < 1 and < < such that, if 1 < r 5 2,
Let
MT5 f (s) = H5 (s) Mf (s) (Re(s) = ):
(4.6.12)
H 5 = W I;;;1!=a ;;a La ; La ;1; T5R:
(4.6.13)
1
1
1
2
Using again Lemma 3.1(ii),(iii) and Theorem 3.2(b),(c), we have that if < 1 ; < and 1 < r 5 s < 1, then H 5 2 [L;r ; L1;;s ]. For f 2 L;2 and Re(s) = 1 ; applying (4.6.13), (3.3.15), (3.3.7), (3.3.8), (4.6.12), (3.3.16) and (4.6.9) we obtain similarly to (4.6.8) that
MH 5 f (s) = s MI;;;1! =a1 ;;a1 La1 ; La2 ;1; T5 Rf (s)
= s ;[a;[a(s1 (;s ; ) ;)]! ] MLa1 ; La2 ;1; T5Rf (s) 1
= s ;[a;[a(s1 (;s ; ) ;)]! ] ;[a1a(1s(s;; );)]1 MLa2 ;1; T5 Rf (1 ; s) (a1) 1 s) ; a2(1 ; )] MT Rf (s) = s ;[a;[a(s1 (;s ; ) ;)]! ] ;[a1a(1s(s;; );)]1 ;[a2 (1 ;a2 [(1 5 (a1) (a2 ) ;s);(1; )] 1 2 a2( ; s)] H ( s ) M Rf (s) = s ; [a1 (s ; )];[ 5 ;[a1 (s ; ) ; ! ](a1)a1 (s; );1 (a2)a2 ( ;s)
= H(s) Mf (1 ; s):
(4.6.14)
Applying this equality and using similar arguments to those in the case Re(! ) = 0, we complete the proof for Re(! ) < 0. Hence the theorem is proved.
112
H -Transform on the Space L
Chapter 4.
;r
4.7. Boundedness and Range of the H -Transform When a > 0 and a1 = 0 or a2 = 0
In this section we consider the cases when a1 > 0; a2 = 0 and a1 = 0; a2 > 0. First we treat the former case.
Theorem 4.7. Let a1 > 0; a2 = 0; m > 0; < 1 ; < and ! = + a1 + 1=2 and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) If Re(!) = 0 and 2= EH ; then
H (L;r ) = La ; ;!=a (L;r ):
(4.7.1)
1
1
When 2 EH ; H (L;r ) is a subset of the right-hand side of (4:7:1): (c) If Re(!) < 0 and 2= EH ; then
H (L;r ) =
I;;;1!=a1 ;;a1 La1 ; (L;r ): (4.7.2) When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.7.2). Proof. We rst consider the case Re(!) = 0. We de ne H6(s) by a(s; )+!;1 (4.7.3) H6(s) = ;[(aa1)(s1 ; ) + !] ;s H(s): 1 Since Re(! ) = 0, H6 (s) is analytic in the strip < Re(s) < . Arguments similar to those in (4.6.4) and (4.6.5) lead to the estimates q p Y Re(bj );1=2 Y 1=2;Re(ai ) j i 6 ( + it) j =1 i=1
H
(2)c;1=2(a1);1=2e;c +1=2eIm(!;)sign(t)=2 and
H0 ( + it) = H6( + it)
(
a log a ; a
6
1
1
1
(4.7.4)
0 ( + it) ) H [a (s ; ) + ! ] ; log +
H( + it)
1
8 3 2 > ( ; ) + Re(! ) ; 1 > < a 6log(iat) + 1 2 775 6 ( + it) >a1 log a1 ; a1 6 1 4 ia1t > :
=H
; log +
log + a log(it) + Re() + 1
it
+ O t12
(4.7.5) = O t12 (jtj ! 1) uniformly in in any bounded interval of R. So H6 2 A with (H6 ) = and (H6 ) = and Theorem 3.1 implies that there is a transform T6 2 [L;r ] for 1 < r < 1 and < < , and if 1 < r 5 2, then
MT6 f (s) = H6 (s) Mf (s) (Re(s) = ):
(4.7.6)
4.7. Boundedness and Range of the H -Transform When a > 0 and a1 = 0 or a2 = 0
We set
113
H 6 = WLa ; ;!=a RT6R:
(4.7.7) Then it follows from Lemma 3.1(ii),(iii) and Theorem 3.2(c) that, if < < and 1 < r 5 s < 1, H 6 2 [L;r ; L1;;s ]. For f 2 L;2 applying (4.7.7), (3.3.15), (3.3.8), (4.7.6), (3.3.16) and (4.7.3), we obtain for Re(s) = 1 ; MH 6 f (s) = MW La1 ; ;!=a1 RT6Rf (s)
1
1
= s MLa1 ; ;!=a1 RT6 Rf (s) !=a1 )] MRT6Rf (1 ; s) = s ;[a1 (as1 (;s; ++!=a );1 1 (a1) ) + ! ] MT Rf (s) = s ;[a1 (as1 (;s; )+ 6 !;1 (a1 ) ) + ! ] H (s)MRf (s) = s ;[a1 (as1 (;s; )+ 6 !;1 (a1 ) ) + ! ] H (s)Mf (1 ; s) = s ;[a1 (as1 (;s; )+ 6 !;1 (a1 )
= H(s) Mf (1 ; s): (4.7.8) Applying this relation and using arguments similar to those in the case Re(! ) = 0 of Theorem 4.6 we complete the proof of the theorem for Re(! ) = 0. Now we consider the case Re(! ) < 0. Let us de ne H7 (s) by ( a1)a1 (s; );1 ;[a1 (s ; ) ; ! ] ;s H(s): (4.7.9) H7(s) = ;2 [a1(s ; )] H7(s) is analytic in the strip < Re(s) < , and in accordance with (1.2.9), (3.4.14), (4.3.4) and (3.4.19), we have q
p
H7( + it) Y jRe(b );1=2 Y 1i =2;Re(a )(2)c ;1=2e;c +1=2 j
j =1
i
i=1
(a1);Re();a1 ;1eIm(!;)sign(t)=2; "
H07( + it) = H7( + it) a1 log a1 + a1
(4.7.10)
[a1(s ; ) ; ! ]
0( + it) # H ;2a1 [a1(s ; )] ; log + H( + it) = O t12
(4.7.11)
as jtj ! 1 uniformly in on any bounded interval of R. So H7 2 A with (H7) = and (H7 ) = . By Theorem 3.1, there is T7 2 [L;r ] for 1 < r < 1 and < < , so that, if 1 < r 5 2,
MT7 f (s) = H7 (s) Mf (s) (Re(s) = ):
(4.7.12)
114
Chapter 4.
Setting
H -Transform on the Space L
H 7 = W I;;;1!=a ;;a La ; RT7R;
1
1
1
;r
(4.7.13)
we see H 7 2 [L;r ; L1;;s ], if < 1 ; < and 1 < r 5 s < 1; by virtue of Lemma 3.1(ii),(iii) and Theorem 3.2(b),(c). For f 2 L;2 and Re(s) = 1 ; , applying (4.7.13), (3.3.15), (3.3.7), (3.3.8), (3.3.16) and (4.7.12), we obtain similarly to (4.6.8) that
MH 7 f (s) = MW I;;;1! =a1 ;;a1 La1 ; RT7Rf (s)
= s MI;;;1! =a1 ;;a1 La1 ; RT7 Rf (s) = s ;[a;[a(s1 (;s ; ) ;)]! ] MLa1 ; RT7Rf (s) 1 2 = s ; [a1(s ; )]a1 (s; );1 MRT7Rf (1 ; s) ;[a1 (s ; ) ; ! ](a1) 2 = s ; [a1(s ; )]a1 (s; );1 MT7 Rf (s) ;[a1 (s ; ) ; ! ](a1) 2 = s ; [a1(s ; )]a1 (s; );1 H7 (s) MRf (s) ;[a1 (s ; ) ; ! ](a1)
= H(s) Mf (1 ; s):
(4.7.14)
Using this relation and arguments similar to those in the case Re(! ) < 0 of Theorem 4.6, we obtain the result for Re(! ) < 0. In the case a1 = 0 and a2 > 0 the following statement is valid.
Theorem 4.8. Let a1 = 0; a2 > 0; n > 0; < 1 ; < and ! = ; a2 + 1=2 and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) If Re(!) = 0 and 2= EH ; then
H (L;r ) = L;a ; +!=a (L;r ): 2
2
When 2 EH ; H (L;r ) is a subset of the right-hand side of (4:7:15): (c) If Re(!) < 0 and 2= EH ; then
H (L;r ) =
;! L;a ; (L;r ): I0+;1 =a2 ;a2 ;1 2
(4.7.15)
(4.7.16)
When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.7.16). Proof. The proof is derived from Theorem 4.7 by examing RT R and by invoking (3.3.17), (3.3.18) similarly to what was done in the proof of Theorem 4.4.
4.8. Boundedness and Range of the H -Transform When a > 0 and a1 < 0 or a2 < 0
115
4.8. Boundedness and Range of the H -Transform When a > 0 and a1 < 0 or a2 < 0 In this section we give conditions for the transform H to be one-to-one on L;r and characterize its range on L;r except for its isolated values 2 EH in terms of the modi ed Laplace transform Lk; , modi ed Hankel transform H k; and elementary transform M given in (3.3.3), (3.3.4) and (3.3.11). The results will be di erent in the cases a1 > 0; a2 < 0 and a1 < 0; a2 > 0. We rst consider the former case.
Theorem 4.9. Let a > 0; a1 > 0; a2 < 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
(4.8.1)
aRe() = (r) + 2a2 ( ; 1) + Re(); Re( ) > ; 1; Re( ) < 1 ; ; where (r) is given in (3:3:9): If 2= EH ; then
H (L;r ) =
(4.8.2) (4.8.3) (4.8.4)
M1=2+!=(2a2)H ;2a2 ;2a2 +!;1 L;a ;1=2+;!=(2a2 ) L3=2;+Re(!)=(2a2);r : (4.8.5)
When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.8.5). Proof. We denote by H8(s) the function
)a(s+);1 jaj;2a2 s;! ;[a (s + ) + ! ] ( a 2 2 ;s H(s): H8(s) = ;[a (s + )];[a2( ; s)]
(4.8.6)
For Re(s) = 1; , by virtue of the assumptions (4.8.1), (4.8.2), (4.8.4) and relations (r) = 1=2; a2 < 0, we have Re[a2(s + ) + ! ] = a2[1 ; + Re( )] + aRe( ) ; Re() ; 21 = a2[1 ; + Re( )] + [ (r) + 2a2( ; 1) + Re()] ; Re() ; 21 = a2[ ; 1 + Re( )] + (r) ; 12 = a2[ ; 1 + Re( )] > 0; and hence the function H8 (s) is analytic in the strip < Re(s) < . Applying (1.2.9), (3.4.14), (4.3.4) and (3.4.19) we obtain the estimates q
p
H8( + it) Y jRe(b );1=2 Y 1i =2;Re(b ) j =1
j
j
i=1
(2)c;1=2(a);1=2e;c +1=2e;Im(!;a+)sign(t)=2
(4.8.7)
116
Chapter 4.
and
H -Transform on the Space L
;r
(
H08( + it) = H8( + it) a log a ; 2a2 log ja2j + a2 [a2(s + ) + !] 0 ;a [a(s + )] + a2 [a2( ; s)] ; log + HH(( ++ itit))
)
(4.8.8) = O t12 as jtj ! 1, uniformly in on any bounded interval of R: So H8 2 A with (H8) = and (H8) = and by Theorem 3.1, there is a transform T8 2 [L;r ] for 1 < r < 1 and < < so that, if 1 < r 5 2, MT8 f (s) = H8 (s) Mf (s) (Re(s) = ): (4.8.9) Let H 8 = W M1=2+!=(2a2)H ;2a2 ;2a2+!;1 L;a ;1=2+;!=(2a2)M;1=2;!=(2a2)T8R: (4.8.10) It is directly veri ed that under the conditions of the theorem, Lemma 3.1 and Theorem 3.2(c),(d) yield H 8 2 [L;r ; L1;;r ]. If f 2 L;2 , then applying (4.8.10), (3.3.15), (3.3.14), (3.3.10), (3.3.9), (3.3.14), (4.8.9), (3.3.16) and (4.8.6), we have for Re(s) = 1 ; MH 8 f (s)
= MW M1=2+!=(2a2 )H ;2a2 ;2a2 +!;1 L;a ;1=2+;!=(2a2) M;1=2;!=(2a2 ) T8Rf (s)
= s MM1=2+!=(2a2 )H ;2a2 ;2a2 +!;1 L;a ;1=2+;!=(2a2) M;1=2;!=(2a2 ) T8Rf (s) ! 1 s = MH ;2a2 ;2a2 +!;1 L;a ;1=2+;!=(2a2) M;1=2;!=(2a2 ) T8Rf s + 2 + 2a 2 s)] = s ja2 j2a2 s+! ;[a;[a(s2 (+ ; ) + !] 2 ML;a;1=2+;!=(2a2)M;1=2;!=(2a2)T8Rf 21 ; s ; 2!a 2 a (s + )] = s ja2 j2a2 s+! (a)1;a(s+) ;[a2;[(a; (ss)];[ 2 + ) + !] 1 ! MM;1=2;!=(2a2)T8Rf 2 + s + 2a 2 a(s + )] MT Rf (s) = s ja2 j2a2 s+! (a)1;a(s+) ;[a2;[(a; (ss)];[ 8 2 + ) + !] a(s + )] H (s)MRf (s) = s ja2 j2a2 s+! (a)1;a(s+) ;[a2;[(a; (ss)];[ 8 2 + ) + !]
= H(s) Mf (1 ; s):
(4.8.11)
4.8. Boundedness and Range of the H -Transform When a > 0 and a1 < 0 or a2 < 0 117 So we have that, for f 2 L;2 , M 8 f (s) = M f (s) with Re(s) = 1 ; . Thus on L;2 . By the fact that L;2 \ L;r is dense in L;r (see Rooney 8 f = f and 8 = [2, Lemma 2.2]), can be extended from L;2 to L;r , if we de ne it by (4.8.10). Moreover, (4.8.5) holds if and only if T8 (L1;;r ) = L1;;r . Taking arguments similar to
H
H
H
H H H
H
those in Theorem 4.7, we can show that the latter holds if 2= EH . Further, the transforms
M;1=2;!=(2a2 )T8R;
L;a ;1=2+;!=(2a2) ;
H ;2a2 ;2a2 +!;1
are one-to-one as respective operators in the corresponding spaces. Then, H is one-to-one if and only if T8 is one-to-one. This is so, if 1 < r 5 2; or if 2= EH , which can be proved as in Theorem 4.7. This completes the proof of the theorem.
Corollary 4.9.1. Let a > 0; a1 > 0; a2 < 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) Let ! = a ; ; 1=2 and let and be chosen such that either of the following
conditions holds:
(i) aRe( ) = (r) ; 2a2 + Re(); Re( ) = ; ; Re( ) 5 ; if m > 0; n > 0; (ii) aRe( ) = (r) ; 2a2 + Re(); Re( ) > ; 1; Re( ) < 1 ; ; if m = 0; n > 0; (iii) aRe( ) = (r) + 2a2( ; 1) + Re(); Re( ) = ; ; Re( ) 5 ; if m > 0; n = 0:
Then; if 2= EH ; H (L;r ) can be represented by the relation (4:8:5). When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.8.5). Proof. By assumptions < 1 ; < and a2 < 0, if < 1 and the relation
a Re( ) = (r) ; 2a2 + Re()
(4.8.12)
holds, then (4.8.2) is valid. If > ;1 and the relations Re( ) = ; ;
Re( ) 5
(4.8.13)
hold, then (4.8.3) and (4.8.4) are true. Therefore the corollary follows from Theorem 4.9. The next assertion follows from Corollary 4.9.1(i), if we set = ; .
Corollary 4.9.2. Let a > 0; a1 > 0; a2 < 0; m > 0; n > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) Let a ; 2a2 +Re()+ (r) 5 0; ! = ;a ; ; 1=2 and let be chosen such that Re( ) 5 . Then if 2= EH ; H (L;r ) can be represented in the form (4:8:5). When 2 EH ;
H (L;r ) is a subset of the right-hand side of (4.8.5).
Finally we consider the case when a > 0; a1 < 0 and a2 > 0.
Theorem 4.10. Let a > 0; a1 < 0; a2 > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r .
118
Chapter 4.
H -Transform on the Space L
;r
(b) Let !; ; 2 C be chosen as
! = a ; ; ; 21 ;
(4.8.14)
aRe() = (r) ; 2a1 + + Re(); Re( ) > ; ; Re( ) < :
(4.8.15) (4.8.16) (4.8.17)
If 2= EH ; then
H (L;r )
= M;1=2;!=(2a1) H 2a1 ;2a1 +!;1 La ;1=2;+!=(2a1) L1=2; ;Re(!)=(2a1);r : (4.8.18) When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.8.18). Proof. The proof is derived from Theorem 4.9 by examing RTR similarly to that which was done in Theorem 4.4.
Corollary 4.10.1. Let a > 0; a1 < 0; a2 > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) Let ! = a ; ; ; 1=2 and let and be chosen such that either of the following
conditions holds: (i) aRe( ) = (r) ; 2a1(1 ; )++Re(); Re( ) = ; 1; Re( ) 5 1 ; ; if m > 0; n > 0; (ii) aRe( ) = (r) ; 2a1 + + Re(); Re( ) = ; 1; Re( ) 5 1 ; ; if m = 0; n > 0; (iii) aRe( ) = (r) ; 2a1(1 ; ) + + Re(); Re( ) > ;; Re( ) < ; if m > 0; n = 0: Then; if 2= EH ; H (L;r ) can be represented by the relation (4:8:18): When 2 EH ; H (L;r ) is a subset of the set in the right-hand side of (4.8.18).
Corollary 4.10.2. Let a > 0; a1 < 0; a2 > 0; m > 0; n > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H is one-to-one on L;r . (b) Let 2a1 ; a + Re() + (r) 5 0; ! = a ; 2a1 ; ; 1=2 and let be chosen such that Re( ) 5 1 ; . Then; if 2= EH ; H (L;r ) can be represented by the relation (4:8:18): When 2 EH ; H (L;r ) is a subset of the right-hand side of (4.8.18). 4.9. Inversion of the H -Transform When = 0 In Sections 4.1{4.4 and 4.6{4.8 we have proved that for certain ranges of parameters, the
H -transform (3.1.1) has the representation (4.1.4) or (4.1.5). In this and the next sections we show that the inversion of the H -transform has the respective forms: d x(+1)=h f (x) = hx1;(+1)=h dx
4.9. Inversion of the H -Transform When = 0
Z
119
# (;; h); (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i )1;n xt (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m ; (; ; 1; h) (H f )(t)dt (4.9.1)
1 q;m;p;n+1 H p+1;q+1 0
"
or
d x(+1)=h f (x) = ;hx1;(+1)=h dx
# (1 ; ai ; i ; i )n+1;p; (1 ; ai ; i ; i )1;n; (;; h) xt (; ; 1; h); (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m (H f )(t)dt; (4.9.2)
1 q;m+1;p;n H p+1;q+1 0
Z
"
provided that a = 0. The conditions for the validity of the relations (4.9.1) and (4.9.2) will be di erent in the cases = 0 and 6= 0. Here we consider the rst one. If f 2 L;2 , and H is de ned on L;r , then according to Theorem 4.1, the equality (4.1.1) holds under the assumption there. This fact implies the relation MH f (1 ; s)
Mf (s) =
(4.9.3)
H(1 ; s)
for Re(s) = . By (1.1.2) we have " # 1 = Hq;m;p;n (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i)1;n s H(1 ; s) p;q (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m H0(s);
(4.9.4)
and hence (4.9.3) takes the form
(Mf )(s) = (MH f )(1 ; s)H0 (s) (Re(s) = ):
(4.9.5)
We denote 0 ; 0; a0; a01; a02; 0; 0 and 0 for H0 instead of those for H. Then we nd #
"
8 > > > <
max Re(b m+1 ) ; 1 + 1; ; Re(b q ) ; 1 + 1 m+1 q
if q > m;
> > :
;1
if q = m;
0 = >
"
#
8 > > > <
min Re (an+1 ) + 1; ; Re (ap ) + 1 if p > n; n+1 p
> > :
1
0 = >
(4.9.6)
if p = n; a0 = ;a ; a01 = ;a2 ; a02 = ;a1; 0 = ; 0 = ; 0 = ; ; :
We also note that if 0 < < 0, is not in the exceptional set of H0 . First we consider the case r = 2.
(4.9.7) (4.9.8)
120
Chapter 4.
Theorem 4.11.
H -Transform on the Space L
;r
< 1 ; < ; 0 < < 0; a = 0 (1 ; ) + Re() = 0 f 2 L;2 (4:9:1) Re() > h ; 1 (4:9:2) Re() < h ; 1. Proof. We apply Theorem 3.6 with H being replaced by H0 and by 1 ; . By the assumption and (4.9.8) we have Let
and
. Then the relation
holds for
. Let
and
for
a0 = ;a = 0; 0[1 ; (1 ; )] + Re(0 ) = ; Re() ; = ;[(1 ; ) + Re()] = 0
(4.9.9) (4.9.10)
and 0 < 1 ; (1 ; ) < 0, and thus Theorem 3.6(i) applies. Then there is a one-to-one transform H 0 2 [L1;;2 ; L;2 ] so that the relation MH 0f (s) = H0 (s) Mf (1 ; s)
(4.9.11)
holds for f 2 L1;;2 and Re(s) = . Further, if f 2 L;2 , H f 2 L1;;2 and it follows from (4.9.11), (4.1.1) and (4.9.4) that MH 0 H f (s) = H0(s) MH f (1 ; s) = H0 (s)H(1 ; s) Mf (s) = Mf (s);
if Re(s) = . Hence MH 0 H f = Mf and
H Hf = f 0
for f 2 L;2 :
(4.9.12)
Applying Theorem 3.6(ii) again, we obtain for f 2 L1;;2 that
Hf
0
d x(+1)=h (x) = hx1;(+1)=h dx
1 q;m;p;n+1 " H p+1;q+1 xt 0
Z
# (;; h); (1 ; ai ; i ; i )n+1;p; (1 ; ai ; i ; i )1;n (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m; (; ; 1; h) f (t)dt; (4.9.13)
if Re() > [1 ; (1 ; )]h ; 1 and H 0f (x) = ;hx1;(+1)=h dxd x(+1)=h # " Z 1 (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n ; (;; h) q ; m +1;p;n H p+1;q+1 xt 0 (; ; 1; h); (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m f (t)dt; (4.9.14) if Re() < [1 ; (1 ; )]h ; 1. Replacing f by H f and using (4.9.12), we have the relations (4.9.1) and (4.9.2) for f 2 L;2 , if Re() > h ; 1 and Re() < h ; 1, respectively, which completes the proof of the theorem. The next result is an extension of Theorem 4.11 to L;r -spaces for any 1 < r < 1; provided that = 0 and Re() = 0.
4.10. Inversion of the H -Transform When = 0
121
6
Theorem 4.12.
< 1 ; < ; 0 < < 0 ; a = 0; = 0 Re() = 0 f 2 L;r (1 < r < 1); (4:9:1) Re() > h ; 1 (4:9:2) Re() < h ; 1. Proof. We apply Theorem 4.1 with H replaced by H0 in (4.9.4) and by 1 ; . From the assumption and (4.9.8), we have a0 = 0 = 0; Re(0 ) = 0 and 0 < 1 ; (1 ; ) < 0, and thus Theorem 4.1(i) can be applied. Due to the theorem, H 0 can be extended to L1;;r as an element of [L1;;r ; L;r ]. By virtue of (4.9.12) H 0 H is an identical operator in L;2 . By Rooney [2, Lemma 2.2] L;2 is dense in L;r and since H 2 [L;r ; L1;;r ] and H 0 2 [L1;;r ; L;r ], the operator H 0H is identical on L;r and hence Let
If
and
the relation
holds for
H Hf = f 0
and
for f 2 L;r :
.
for
(4.9.15)
Applying Theorem 4.1(e) with H being replaced by H0 and by 1 ; , we obtain that the relations (4.9.13) and (4.9.14) hold for f 2 L1;;r , when Re() > [1 ; (1 ; )]h ; 1 and Re() < [1 ; (1 ; )]h ; 1, respectively. Replacing f by H f and using (4.9.15), we arrive at (4.9.1) and (4.9.2) for f 2 L1;;r , if Re() > h ; 1 and Re() < h ; 1, respectively, which completes the proof of the theorem.
4.10. Inversion of the H -Transform When 6= 0
We now investigate under what conditions the H -transform with 6= 0 will have an inverse of the form (4.9.1) or (4.9.2). First, we consider the case > 0. To obtain the inversion of the H -transform on L;r we use the relation (4.1.3).
Theorem 4.13.
m > 0; a = 0; > 0; < 1 ; < ; 0 < < minf 0; [Re( + 1=2)=]+1g; (1 ; )+Re() 5 1=2 ; (r) 1 < r < 1 f 2 L;r ; (4:9:1) (4:9:2) Re() > h ; 1 Re() < h ; 1; Proof. According to Theorem 4.3(a), the H -transform is de ned on L;r . First we consider the case Re() > h ; 1. Let H1(t) be the function Let
and let
and
hold for
;n+1 H1(t) = H qp;+1m;p ;q+1
. If
and
then the relations
respectively.
# (;; h); (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i )1;n t : (4.10.1) (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m ; (; ; 1; h)
"
e e and e for H1 instead of those for H; then If we denote ea ; ;
a = ;a = 0; e = ; e = > 0; e = ; ; ; 1: e
(4.10.2)
We prove that H1 2 L;s for any s (1 5 s < 1). For this, we rst apply the results in Sections 1.5, 1.6 and 1.8, 1.9 to H1 (t) to nd its asymptotic behavior at zero and in nity. According to (4.9.6), (4.9.7) and the assumption, we nd Re(bj ) ; 1 + 1 5 < 5 Re(ai ) + 1 (j = m + 1; ; q ; i = n + 1; ; p); 0 0 j i Re(bj ) ; 1 + 1 5 < < Re() + 1 (j = m + 1; ; q ): 0 j h
122
Chapter 4.
H -Transform on the Space L
;r
Then it follows that the poles aik = ai + k + 1 (i = n + 1; ; p; k = 0; 1; 2; ); i n = + h1 + n (n = 0; 1; 2; ) of the gamma functions ;(ai + i ; i s) (i = n + 1; ; p) and ;(1 + ; hs), and the poles bjl = bj ; 1 ; l + 1 (j = m + 1; ; q ; l = 0; 1; 2; ) j of the gamma functions ;(1 ; bj ; j + j s) (j = m + 1; ; q ) do not coincide. Hence by Theorems 1.11{1.13 and Remark 1.5, we have "
#
H1(t) = O(t; 0 ) (t ! 0) with 0 = m+1 max Re(b j ) ; 1 + 1; 5j 5q j
(4.10.3)
if the poles bjl (j = m + 1; ; q ; l = 0; 1; 2; ) are all simple, or
H1(t) = O(t; 0 [log t]N ;1) (t ! 0); if the gamma functions ;(1 ; bj ; j + j s) (j = m + 1; ; q ) have general poles of order N = 2 at some point. Further by Theorems 1.7{1.9 and Remark 1.3, 3 2 1 Re() + 7 6 H1(t) = O t%1 (t ! 1) with 0 = min 64 0 ; 2 + 1; Re(h) + 1 75 ; (4.10.4) if the poles aik (i = n + 1; ; p; k = 0; 1; 2; ) are all simple, or H1 (t) = O t; 0 [log(t)]M ;1 (t ! 1);
if the gamma functions ;(1 + ; hs); ;(ai + i ; i s) (i = n + 1; ; p) have general poles of order M = 2 at some point. Let the gamma functions ;(1 ; bj ; + j s) (j = m + 1; ; q ) and ;(1 + ; hs); ;(ai + i ; i s) (i = n +1; ; p) have simple poles. Then from (4.10.3) and (4.10.4) we see that, for 1 5 s < 1, H1 (t) 2 L;s if and only if, for some R1 and R2; 0 < R1 < R2 < 1, the integrals Z 0
R1
ts( ; 0 );1 dt;
1 s( ; );1 t 0 dt R2
Z
(4.10.5)
are convergent. Since by the assumption > 0 , the rst integral in (4.10.5) converges. In view of our assumptions Re() + 12 Re() + 1 + 1 ; < < 0 ; < h we nd ; 0 < 0 and the second integral in (4.10.5) converges, too.
4.10. Inversion of the H -Transform When = 0
123
6
If the gamma functions ;(1 ; bj ; j + j s) (j = m + 1; ; q ) or ;(1 + ; hs); ;(ai + i ; is) (i = n + 1; ; p) have general poles, then the logarithmic multipliers [log(t)]N ;1 (N = 2; 3; ) may be added in the rst integral in (4.10.5), but they do not in uence its convergence. This is similar to the case when the gamma functions ;(1 ; ; hs) and ;(ai + i ; i s) (i = n + 1; ; p) have general poles of order M = 2. Hence, we have
H1(t) 2 L;s (1 5 s < 1):
(4.10.6)
Let a be a positive number and a denote the operator
a f (x) = f (ax) (x > 0)
(4.10.7)
for a function f de ned almost everywhere on (0; 1). By (3.3.12), a f (x) = W1=af (x) and hence in accordance with Lemma 3.1(ii), a is a bounded isomorphism of L;r onto itself, and if f 2 L;r (1 5 r 5 2); there holds the relation for the Mellin transform M
Ma f (s) = a;s Mf (s) (Re(s) = ):
(4.10.8)
By virtue of Theorem 4.3(d) and (4.10.6), if f 2 L;r and H1 2 L;r (and hence x H1 2 L;r ), then 0
0
1
Z 0
H1(xt)
Hf
(t)dt =
1
Z
0
Hf
x H1 (t)
(t)dt =
Z
1 0
H xH
1
(t)f (t)dt:
(4.10.9)
From the assumption (1 ; ) + Re() 5 1=2 ; (r) 5 0, Theorem 4.3(b) and (4.10.8) imply that MH x H1 (s) = H(s) Mx H1 (1 ; s) = x;(1;s) H(s) MH1 (1 ; s)
(4.10.10)
for Re(s) = 1 ; . Now from (4.10.6), H1(t) 2 L;1 . Then by the de nitions of the H -function (1.1.1) and the direct and inverse Mellin transforms (2.5.1) and (2.5.3), we have
MH1
;n+1 (s) = Hqp;+1m;p ;q+1
;m;p;n = Hqp;q
"
= 1 +H0 (;s)hs
# (;; h); (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i )1;n s (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m ; (; ; 1; h) (1 ; ai ; i ; i )n+1;p; (1 ; ai ; i ; i )1;n # ;(1 + ; hs) s (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m ;(2 + ; hs)
"
for Re(s) = , where H0 is given in (4.9.4). Thus for Re(s) = 1 ; , 1 H0(1 ; s) = MH1 (1 ; s) = 1 + ; h(1 ; s) H(s)[1 + ; h(1 ; s)] : Substituting this into (4.10.10) we obtain
MH x H1 (s) =
x;(1;s) 1 + ; h(1 ; s) (Re(s) = 1 ; ):
(4.10.11)
124
Chapter 4.
H -Transform on the Space L
;r
For x > 0 let us consider the function 8 1 t(+1)=h;1 if 0 < t < x; > > < gx(t) = > h > : 0 if t > x:
(4.10.12)
Then we have for Re() > h ; hRe(s) ; 1
Mgx (s) =
xs+(+1)=h;1 ; 1 + ; h(1 ; s)
and (4.10.11) takes the form MH x H1 (s) = M[x;(+1)=h gx)] (s);
which implies
H xH
1
(t) = x;(+1)=hgx (t):
(4.10.13)
Substituting (4.10.13) into (4.10.9), we have Z
1
0
H1(xt)
Hf
Z 1 ; (+1)=h (t)dt = x gx(t)f (t)dt
0
or, by virtue of (4.10.12), Z 0
Z 1 x (+1)=h;1 t f (t)dt = hx(+1)=h H 0
1
(xt)
Hf
(t)dt:
Di erentiating this relation, we obtain
d x(+1)=h f (x) = hx1;(+1)=h dx
1
Z 0
H1(xt)
Hf
(t)dt;
which shows (4.9.1). When Re() < h ; 1, the relation (4.9.2) is proved similarly to (4.9.1), by taking the function " # (1 ; a ; ; ) i i i n+1;p; (1 ; ai ; i ; i )1;n; (;; h) q ; m +1;p;n H2(t) = H p+1;q+1 t (4.10.14) (; ; 1; h); (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m instead of the function H1(t) of (4.10.1). This completes the proof of the theorem. In the case < 0 the following statement gives the inversion of the H -transform on L;r .
Theorem 4.14.
n > 0; a = 0; < 0; < 1 ; < ; max[ 0; fRe( +1=2)=g +1] < < 0; (1 ; ) + Re() 5 1=2 ; (r) 1 < r < 1 f 2 L;r ; (4:9:1) (4:9:2) Re() > h ; 1 Re() < h ; 1; Let
and let
and
hold for
and for
If
then the relations
respectively.
This theorem can be proved similarly to Theorem 4.13, if we apply Theorem 4.4 instead of Theorem 4.3 and take into account the asymptotics of the H -function at in nity and zero
4.10. Inversion of the H -Transform When = 0
125
6
given in Sections 1.5, 1.6 and 1.8, 1.9.
Remark 4.2. Formal di erentiation of the right sides of (4.9.1) and (4.9.2) under the integral sign yields the relation " # Z 1 (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n q ; m;p ; n f (x) = Hp;q xt H f (t)dt: (4.10.15) 0 (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m In fact, applying (2.2.1) to (4.9.1), we obtain f (x) = hx1;(+1)=h d(dxt) (xt)(+1)=h " Z 1 (;; h); (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i )1;n q ; m;p ; n +1 Hp+1;q+1 xt 0 (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m ; (; ; 1; h)
t;
=h
1 ( +1)
=h
Hf
#
(t)dt
(;( + 1)=h; 1); (;; h); (1 ; bj ; j ; j )m+1;q ; # (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i)1;n H f (t)dt: (1 ; bj ; j ; j )1;m ; (; ; 1; h); (1 ; ( + 1)=h; 1)
1 q;m;p;n+2 " Hp+2;q+2 xt 0
Z
(4.10.16)
According to (1.1.1){(1.1.2) and (2.2.14) we have 2 + 1 ; 1 ; (;; h); (1 ; a ; ; ) ; ; i i i n+1;p ;m;p;n+2 4xt hHpq+2 h ;q+2 (1 ; b ; ; ) j j i m+1;q ; (1 ; bj ; j ; j )1;m; 3 (1 ; ai ; i ; i)1;n 7 5 + 1 (; ; 1; h); 1 ; h ; 1 + 1 Z ; 1 + h ; s ;(1 + ; hs) = 21i h L ;(2 + ; hs); +h 1 ; s # " (1 ; a ; ; ) i i i n +1;p ; (1 ; ai ; i ; i )1;n ;s ds Hqp;q;m;p;n s (xt) (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m " Z (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i)1;n # ;s 1 m;n ds = 2i Hp;q s (xt) L (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m " # (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n q ; m;p ; n = Hp;q xt : (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m Substituting this relation into (4.10.16), we arrive at (4.10.15).
126
Chapter 4.
H -Transform on the Space L
;r
Similar calculations for (4.9.2) also yields the same result (4.10.15) by virtue of (2.2.2).
4.11. Bibliographical Remarks and Additional Information on Chapter 4
For Sections 4.1{4.8. As was indicated in Section 3.7, several papers were devoted to the mapping properties of the integral transforms (3.1.1) with H-function kernel in the space Lr (R+ ) (1 < r < 1). Fox [2] rst studied such properties in the space L2 (R+ ). He [2, Theorem 5] proved that the special H -transform Z 1 Z x (4.11.1) H f (x) = dxd 0 H1(xt)f(t) dtt with H1(x) = 0 H2q;pp;2q(t)dt; where the kernel H2q;pp;2q(z) is given by (1.11.1), belong to L2 (R+ ) provided that f(x) 2 L2 (R+ ) and the conditions in (1.11.3) hold. Kesarwani [11] obtained such a result for two integral transforms of the form (4.11.1) Z 1 Z x (4.11.2) H f (x) = dxd 0 H2(xt)f(t) dtt with H2(x) = 0 Hpm;p +q;m+n (t)dt and Z 1 Z x (4.11.3) H f (x) = dxd 0 H3(xt)f(t) dtt with H3(z) = 0 Hqn;q+p;n+m (t)dt; n;q where the H-functions Hpm;p +q;m+n (x) and Hq+p;n+m (x) are specially given by 3 2 i i ; ; b ; ; 1 ; a ; i i i i 6 2 2 1;q 77 (x > 0) 1;p (4.11.4) Hpm;p x +q;m+n 6 5 4 j ;
j; ; 1 ; d ; c ; j j j j 2 2 1;m 1;n and 2 i ; 3 i ; ; a ; 1 ; b ; i 2 i 1;p 7 i 2 i 6 1;q 7 (x > 0); (4.11.5) Hqn;q x +p;n+m 6 5 4
j j ; ; 1 ; c ; ;
d ; j j j j 2 2 1;m 1;n
respectively. Kesarwani [11, Theorem 1] proved that if i > 0 (1 5 i 5 p), i > 0 (1 5 i 5 q), j > 0 (1 5 j 5 m), j > 0 (1 5 j 5 n) and if the following relations are satis ed m ; q = n ; p > 0; a = 0; > 0; Re(ai) > 0 (1 5 i 5 p);
q
X
bi ;
p
X
ai =
m
X
cj ;
i=1 j =1 i=1 Re(bi ) > 0 (1 5 i 5 q);
n
X
j =1
dj ; (4.11.6)
Re(cj ) > 0 (1 5 j 5 m); Re(dj ) > 0 (1 5 j 5 n); then the H -transforms (4.11.2) and (4.11.3) belong to L2 (R+ ) provided that f(x) 2 L2 (R+ ). Formal di erentiation show that (4.11.1), (4.11.2) and (4.11.3) may be represented in the form (3.1.1) with the H-functions (1.11.1), (4.11.4) and (4.11.5) as kernels. R.K. Saxena [8, Lemma 1] showed that a particular case of the H -transform (3.1.1) in the form 3 2 1 c i ; Z 1 (4.11.7) H f (x) = 0 Hp0+;pq;q+q 664xt amji 1mi 1;q bj 1 775 f(t)dt (x > 0) ; ; ; p p 1;p mj mj 1;q
4.11. Bibliographical Remarks and Additional Information on Chapter 4
127
with p > 0; q = 0, mi > 0 (1 5 i 5 q) belongs to L2 (R+ ) provided that f(x) 2 L2 (R+ ), and obtained the formula (4.1.1) of its Mellin transform. Kalla [8, Lemma 1] proved such a result for the more general H -transform considered by R.K. Saxena [8, (32){(34)]. Bhise and Dighe [2] (see also Dighe [1]) studied in the space Lr (R+ ) the compositon of the Erdelyi{ a+1=2 with the generalized H -transform of the form: Kober operator I0+;2 k;
H f (x) = x+
with
1
Z
0
m;n t Hp;q
c(xt)2k
"
#
(ai ; i)1;p f(t)dt (x > 0) (bj ; j )1;q
= 1 ; ; 2k; 2k ; ka ; a > 0; > 0;
arg c(xt)2k <
j ) + 1 > 0; c > 0; k > 0; min Re(b 2k 15j 5m j
a ; 2
(4.11.8)
(4.11.9)
and proved that, if a > ;1=2 and x +ak f(x) 2 L1 (R+ ), the composition again becomes the H -transform of the same form but of greater order:
a+1=2 t +kaH f (x) I0+;2 k k; a 1 ; 1 ; a + a i ; 1 + i 1 2 i 1;p +1 6c(xt)2k 2 2k t Hpm;n +1 ;q+1 6 4 1 a 1 ;1 a j ; 0 bj + 2 j ; 2 2k 2
= x + c;a=2
;
Z
1;q
; ;
3 7 7 f(t)dt: 5
(4.11.10)
Using this relation, Bhise and Dighe [2] proved that the operator in (4.11.8) can be extended as a bounded operator from Lr (R+ ) into Ls (R+ ), provided that r = 1; s = 1; 1s = 1 ; r1 ; > 0; 0 < + r2 ; 1 5 r1 ; ! (4.11.11) 1 Re(a ) 2k ; 1 Re(b ) i j : ;2k min < 1 + + ka ; p < 2k 1 ; max ; 2k 15j 5m
15i5n
j
i
The results presented in Sections 4.1{4.8 concerning the existence, boundedness and representation properties of the H -transforms in the weighted spaces L;r for any 1 < r < 1 were proved by the authors together with S.A. Shlapakov and H.-J. Glaeske in the papers by Kilbas, Saigo and Shlapakov [2]{[3] and Glaeske, Kilbas, Saigo and Shlapakov [1]{[2], and by Betancor and Jerez Diaz [1] independently. We only indicate that Theorems 4.1{4.4 and Theorems 4.5{4.10 were rst given by the authors and Shlapakov in [2] and [3], respectively in the particular case when = 1. It should be noted that our main tool was based on a technique of Mellin transforms developed by Rooney [2] and applied by him in [6] to construct the L;r -theory of G-transforms (3.1.2). The latter is a particular case of the H -transforms (3.1.1) when 1 = p = 1 = = q = 1. Therefore the results in Sections 4.1{4.8 are generalizations of the corresponding results by Rooney [6]. Namely Theorems 6.1{6.4 and 7.1{7.6 in [6] follow from Theorems 4.1{4.10 if we take into account the relation = q ; p (see Section 6.1 in this connection). We also indicate the paper by Betancor and Jerez Diaz [2] in which the conditions were given on a set of positive Borel measure on R+ and on non-negative functions v(x) on which are sucient for the validity of the relation Z
0
1
1=s
H f (x) s d (x)
5K
Z
0
1
1=r
jv(x)f(x)jr dx
(4.11.12)
for the H -transform (3.3.1) and a complex-valued function f(x) on R+ having a compact support, where 1 5 r 5 1, 1 5 s 5 1 and K is a suitable positive constant. The factorization of the
Chapter 4.
128
H -Transform on the Space L
;r
H -transform (3.1.1), its mapping properties and inversion formulas in special spaces of functions were presented in the book by Yakubovich and Luchko [1].
The results presented in these sections on the invertibility of the
For Sections 4.9 and 4.10.
H -transforms (3.1.1) in the space L;r with any 1 < < 1 for a = 0 and = 0 or 6= 0 were proved by the authors together with Shlapakov in Shlapakov, Saigo and Kilbas [1]. It should be noted that the main diculty here is caused by the investigation of the invertibility of the H -transform in
the case 6= 0. This problem is closely connected with nding the explicit asymptotic expansions of the H-function near zero and in nity in the exceptional cases when a = 0 and > 0 or < 0. Such asymptotic expansions in Sections 1.6 and 1.9 were rst obtained by the authors in Kilbas and Saigo [1] (see Section 1.11). The results in Sections 4.9 and 4.10 generalize the corresponding statements by Rooney [6, Theorems 8.1{8.4] which follow from Theorems 4.11{4.14 (see Chapter 6 in this connection). We also characterize other results on the invertability of the H -transforms (3.1.1). Fox [2] rst obtained the inversion formula for the integral transform (4.11.1) with the function H2q;pp;2q (1.11.1) as a kernel in the space L2 (R+ ). In [2, Theorem 5] he proved that if the conditions in (1.11.3) are satis ed and f(x) 2 L2 (R+ ), then the rst relation in (1.11.2) de nes almost everywhere a function g(x) 2 L2 (R+ ) and the second relation also holds almost everywhere, and the Parseval formula holds: 1
Z
0
jf(x)j2 dx =
1
Z
0
jg(x)j2dx:
(4.11.13)
Fox also considered the case of ordinary convergence and showed [2, Theorem 7], that, for f(t)t(1;)2 2 L1 (R+ ) and f(t) being of bounded variation near t = x (x > 0), if
Z
H f (x) =
0
then
1
H2q;pp;2q (xt)f(t)dt;
(4.11.14)
f(x + 0) + f(x ; 0) = Z 1 H q;p (xt)(H f)(t)dt; (4.11.15) 2 0 2p;2q where H2q;pp;2q (x) is given by (1.11.1), + ) ; Re(b ) > j (1 ; ) (1 5 i 5 p; 1 5 j 5 q): (4.11.16) > 0; Re(ai ) > i(12 j 2 Kesarwani [11] extended the above results of Fox [2] to the H -transform with an unsymmetrical Fourier kernel Hpm;p +q;m+n (x) given by (4.11.4). In [11, Theorem 1] he derived the relations of the form (1.11.2) d Z 1 H (xt)f(t) dt ; f(x) = d Z 1 H (xt)g(t) dt (4.11.17) g(x) = dx 2 t dx 0 3 t 0 for H2(x) and H3(x) being given in (4.11.2) and (4.11.3), and for f 2 L2 (R+ ) provided that the conditions in (4.11.6) are satis ed, and he showed the analog of the Parseval relation (4.11.13): Z 1 Z 1 d Z 1 H (xt)f(t)dt (i = 2; 3): (4.11.18) jf(x)j2 dx = g2(x)g3 (x)dx; gi (x) = dx i 0 0 0 In [11, Theorem 2] Kesarwani established for the H -transform
H f (x) =
Z
0
1 m;p Hp+q;m+n (xt)f(t)dt
the inversion formula of the form (4.11.15): f(x + 0) + f(x ; 0) = Z 1 H n;q (xt) H f (t)dt; 2 0 q+p;n+m
(4.11.19) (4.11.20)
4.11. Bibliographical Remarks and Additional Information on Chapter 4
129
where Hqn;q +p;n+m (x) is given by (4.11.5), under the conditions in (4.11.6) and additionally the assumptions i (1 5 i 5 p); Re(b ) > i (1 5 i 5 q); Re(ai ) > 2 i 2 (4.11.21)
j j Re(cj ) > 2 (1 5 j 5 m); Re(dj ) > 2 (1 5 j 5 n);
f(t)t(1;)2 2 L1 (R+ ) and f(t) being of bounded variation near t = x (x > 0). We note that R.U. Verma also used the same arguments as the above to present in [4] the results which were essentially proved by Fox [2], while in [3] R.U. Verma showed that the H -transform
H f (x) =
with the symmetrical kernel m;0 (x) Hm;m
1
Z
0
m;0 (xt)f(t)dt Hm;m
2 1 6 m;0 4x = Hm;m aj
; ai + 2i ; i 1;m ; 2j ; j 1;m
(4.11.22) 3 7 5
has an inversion of the form (4.11.1) Z 1 Z x dt d m;0 (t)dt H4(xt)f(t) t with H4 (x) = Hm;m (4.11.23) f(x) = dx 0 0 under certain conditions. We note that the transform (4.11.22) is reduced to the transform (4.11.19) (considered by Kesarwani [11]) if we put p = n = 0, q = m, bi = 1 ; ai ; ci = ai i = i (1 5 i 5 m) in (4.11.19) and take into acount (4.11.4). On the basis of the Mellin transform of the composition of the Erdelyi{Kober type fractional integral I; ;m; =m = R( ; ; m) with the H -transform (4.11.7) R.K. Saxena [8, Theorem 1] obtained the inversion formula for such a transform in terms of the inverse Laplace transform L;1 : f(x) = p;1=2(2)(1;p)=2 2
p Y
Y q
3
x
R bj m; cj ; cj ; mj H f p 5 ; (4.11.24) L;1 4 R ai +pi ; 1 ; k ; 1; p j j =1 i=1 provided that f(x) 2 L2 (R+ ), (H f)(x) 2 L2 (R+ ) and some other conditions are satis ed. R.K. Saxena
[8, Theorem 2] also indicated the inversion of a more general H -transform than (4.11.7) on the basis of the Mellin transform of its compositions with the Erdelyi{Kober type operators (3.3.1) and (3.3.2). These results were also indicated by Kalla [8]. Kumbhat [1] obtained a result similar to (4.11.24) on the basis of the Mellin transform of the generalized fractional integrals ; ;1 Z x x t f(t)dt; (4.11.25) Rf (x) = ;(1 ; ) 2 F1 ; + m; ; a xt 0 Zx t;;1 f(t)dt (4.11.26) S f (x) = ;(1x; ) 2F1 ; + m; ; a xt 0 with 0 < < 1 involving the Gauss hypergeometric function (2.9.2) in the kernel (considered by Kalla and R.K. Saxena [1], [3]) with a more general H -transform than the one considered by R.K. Saxena [8]. R. Singh [1] and K.C. Gupta and P.K. Mittal [1] used the Mellin transform to obtain the inversion formulas for the integral transform with H-function (1.1.2) in the kernel with L = Li 1 . R. Singh [1] considered the H -transform " # Z 1 (ai ; i)1;p m;n H ;cf (x) = x Hp;q cxt f(t)dt (x > 0) (4.11.27) (bj ; j )1;q 0
Chapter 4.
130
H -Transform on the Space L
;r
with constants c 6= 0 and 6= 0, and proved the inversion formula for x > 0 in the form " # Z 1 (1 ; ai ; i; i)n+1;p ; (1 ; ai ; i ; i)1;n c q ; m;p ; n Hp;q cxt f(x) = (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m 0 H ;c f (t) dtt ; provided that 0 5 n 5 p, 0 5 q 5 m, a > 0, > 0, f(x) is continuous on R+ with f(x) = O (xa ) (x ! 0; a + % > ;1); ; f(x) = O xb (x ! 1; b + % > ;1);
(4.11.28)
(4.11.29)
x ;1 f(x) 2 L1 (R+ ); % + 1 < < % + 1 for
j) ; % max Re(a i ) ; 1 ; % min Re(b 15j 5m j 15i5n i
(4.11.30)
and the integral in (4.11.24) exists and x; ;1 (H ;c f)(x) 2 L1 (R+ ). We note that when c = = 1 and (H f)(x) is replaced by x(H f)(x), then (4.11.28) coincides with the relation (4.10.15) obtained by formal di erentiation of (4.9.1) and (4.9.2) under the integral sign (see Remark 4.2 in Section 4.10). K.C. Gupta and P.K. Mittal [1] obtained the inversion relation 1 [f(x + 0) + f(x ; 0)] 2 # " Z (1 ; ai ; i ; i)n+1;p; (1 ; ai ; i; i)1;n 1 m;n Hp;q (1 ; b ; ; ) ; (1 ; b ; ; ) s = 2i L 1 j j j m+1;q j j j 1;m
s; MH 1;1f (;s)ds
(4.11.31)
for the integral trasform H 1;1 in (4.11.27) with c = = 1, provided that (4.11.32) a > 0; j arg(x)j < a2 ; the conditions in (4.11.29) are satis ed, f(x) is of bounded variation in the neighborhood of the point x and the H 1;1-transform of jf j exists. In [2] K.C. Gupta and P.K. Mittal proved the uniqueness result for the H -transform (3.1.1): if # " Z 1 (ai ; i)1;p m;n f(t)dt = 0 ( 2 C ); (4.11.33) t Hp;q xt (bj ; j )1;q 0 then f(x) = 0 provided that f(x) is continuous on R+ , f(x) = O (xa ) (x ! 0; Re(a + ) + % > ;1); ; f(x) = O xbe;x (x ! 1; Re() > 0)); the conditions in (4.11.32) are satis ed and Re (ai ; 1) ; aj < 0 (i = 1; ; n; j = n + 1; ; p); i j (1 ; b ) b j i > 0 (i = 1; ; m; j = m + 1; ; q): Re + i j
4.11. Bibliographical Remarks and Additional Information on Chapter 4
131
Using the relation (4.1.1) V.P. Saxena [1] and Buschman and Srivastava [1] discussed the inversion M;N formulas for the H m;n p;q -transform (3.1.1) on the basis of its representation as compositions of the H P;Q transform of lower order (M 5 m, N 5 n, P 5 p and Q 5 q) with the known integral transforms. V.P. Saxena [1] considered such compositions with the Laplace transform (2.5.2), the Meijer transform (8.9.1) and the modi ed Varma transform (7.2.15), while Buschman and Srivastava [1] considered the Eredelyi{Kober type fractional integral operators (3.3.1) and (3.3.2). We also mention N. Joshi and J.M.C. Joshi [1] who obtained the real inversion theorem for a certain H -transform. R.K. Saxena and Kushwaha [1] investigated the H -transform
H f (x) =
with the H-function kernel " x
+m H2qp++n;p m+n;2q+n+m
1
Z
0
+m H2qp++n;p m+n;2q+n+m (xt)f(t)dt (x > 0)
(1 ; ai ; i)1;p ; (1 ; ci; i )1;m ; (ai ; i ; i)1;p; (fi ; i )1;n (bj ; j )1;q ; (gj ; j )1;n; (1 ; bj ; j ; j )1;q ; (1 ; dj ; j )1;m
(4.11.34) #
(4.11.35)
showing that the composition of several Erdelyi{Kober type fractional integral operators (3.3.1) and (3.3.2) with the H -transform (4.11.34) yields the H -transform (3.1.1) with the function H2q;pp;2q as a kernel and applied this result to obtain the inversion formula for the transform (4.11.34). Using the technique of the Laplace transform L and its inverse L;1 developed by Fox [4], [5], R.U. Verma obtained in [5] and [9] the inversion formulas for the H -transforms of the forms "
#
;p xt (1 ; ai ; i)1;p ; (ai ; i; i)1;p H f (x) = H20p;q (1 ; bj ; j ; j )1;q 0
1
Z
and
H f (x) =
1
Z
0
Hp;q;20q
"
xt
f(t)dt (x > 0)
(4.11.36)
#
(ai ; c; c)1;p f(t)dt (x > 0; c > 0); (bj ; c)1;q ; (1 ; bj ; c; c)1;q
(4.11.37)
respectively. Nasim [2] treated the special H -transform (3.1.1) of the form
H f (x) =
Z
1
t H0n;;20n
xt
"
#
f(t)dt ( 2 C ) (4.11.38) (bj ; j )1;n; (1 ; cj ; j )1;n and suggested a method for its inversion on the basis of successive application of linear di erential operators of in nite order of the type ;( + ), and operators of the type 1=;( + ), where = ;xd=dx. Moharir and Raj.K. Saxena [1] established the Abelian theorems for the generalized H -transform of the form " # Z 1 (ai ; i)1;p xt m; 0 H f (x) = e H p;q a(xt) (b ; ) f(t)dt (x > 0) (4.11.39) 0 j j 1;q with real > 0 and > 0 provided that a > 0. 0
Chapter 5 MODIFIED H -TRANSFORMS ON THE SPACE L;r 5.1. Modi ed H -Transforms
The present chapter is devoted to studying the following modi cations of the H -transform (3.1.1): # " Z 1 (a ; ) i i 1;p x (5.1.1) H 1f (x) = 0 Hp;qm;n t (b ; ) f (t) dtt ; j j 1;q # " Z 1 t (ai; i )1;p 2 m;n (5.1.2) H f (x) = 0 Hp;q x (b ; ) f (t) dtx ; j j 1;q " # Z 1 (a ; ) i i 1;p m;n H ; f (x) = x 0 Hp;q xt (b ; ) t f (t)dt; (5.1.3) j j 1;q # " Z 1 x (ai; i )1;p 1 m;n (5.1.4) H ;f (x) = x 0 Hp;q t (b ; ) t f (t) dtt ; j j 1;q # " Z 1 t (ai; i )1;p 2 m;n (5.1.5) H ;f (x) = x 0 Hp;q x (b ; ) t f (t) dtx ; j j 1;q where ; 2 C . These transforms are connected with the H -transform (3.1.1) by the relations
Hf Hf H ;f H ;f H ;f
1
2
1
2
H Rf (x); RH f (x); M H M f (x); M H RM f (x) = M RH M f (x) =
(5.1.6)
(x) =
(5.1.7)
(x) =
(x) =
(x) =
(x) =
(5.1.8) M H 1 M f (x);
M H 2 M f (x);
(5.1.9) (5.1.10)
where R and M are operators given in (3.3.13) and (3.3.11). By virtue of relations (5.1.6){ (5.1.10), (4.1.1), (3.3.14) and (3.3.16), the Mellin transforms of the modi ed H -transforms (5.1.1){(5.1.5) for \suciently good" functions f are given by the relations # " ( a ; ) i i 1 ;p M f (s); (5.1.11) MH 1 f (s) = Hm;n s p;q (bj ; j )1;q 133
Chapter 5. Modi ed H -Transforms on the Space L;r
134 MH
2
f (s) = Hm;n p;q
MH ; f (s) = Hm;n p;q
H
M ; f (s) = Hm;n p;q
H
1
M ; f (s) = Hm;n p;q
2
"
(ai ; i)1;p (bj ; j )1;q (ai ; i)1;p (bj ; j )1;q (ai ; i)1;p (bj ; j )1;q (ai ; i)1;p (bj ; j )1;q
"
"
"
"
#
(5.1.12)
(5.1.13)
(5.1.14)
1 ; s Mf (s); #
s+ #
s+
Mf (1 ; s ; + ); Mf (s + + ); #
1 ; s ; Mf (s + + );
(5.1.15)
#
(ai ; i)1;p s is the function de ned in (1.1.2). (bj ; j )1;q It is directly veri ed that for the \suciently good" functions f and g the following formulas hold where Hm;n p;q
1
Z 0 Z 0
1
1
Z 0
1
Z 0 Z 0
1
Z
H g (x)dx =
Z
H ;g (x)dx = H ; g (x)dx =
Z
f (x)
1
2
f (x)
1
H g (x)dx =
f (x)
f (x)
f (x)
1
H ; g 2
(x)dx =
Hf
0
2
1
0
Hf 1
1
(5.1.16)
(5.1.17)
(x)g (x)dx; (x)g (x)dx;
H ; f (x)g(x)dx; 1 H ; f (x)g(x)dx;
(5.1.18)
(5.1.19)
0 Z
2
0
1
Z 0
H ; f 1
(x)g (x)dx:
(5.1.20)
Remark 5.1 The relations (5.1.16){(5.1.20) are the analog of the formulas of fractional
integration by parts for the fractional integration operators (2.7.1) , (2.7.2) and (3.3.1), (3.3.2) (see (2.20) and (18.18) in the book by Samko, Kilbas and Marichev [1]). By Lemma 3.1(i),(iii) the operators M and R are isometric isomorphisms of L;r onto L ;Re( );r and L1;;r ; respectively. Then (5.1.6){(5.1.10) imply that the properties of the transforms (5.1.1){(5.1.5) in L;r -spaces are similar to those for the H -transforms (3.1.1) investigated in Chapters 3 and 4. We shall prove these properties in the following sections. We begin from the transform (5.1.1).
5.2. H -Transform on the Space L;r 1
We consider the transform H 1 de ned in (5.1.1). Since the operator R is an isometric isomorphism of L;r onto L1;;r : R(L;r ) = L1;;r , (5.1.6) and (5.1.11) show that we can apply the results in Chapters 3 and 4 for the transform H to obtain the corresponding results for the transform H 1.
5.2.
H -Transform on the Space L 1
135
;r
We still use the notation a ; ; ; ; a1 ; a2 ; and in (1.1.7), (1.1.8), (1.1.9), (1.1.10), (1.1.11), (1.1.12), (3.4.1) and (3.4.2), and let EH be the exceptional set of the function Hm;n p;q (s) in (1.1.2) given in De nition 3.4. >From Theorems 3.6, 3.7 and 4.1{4.10 we obtain the L;2 and L;r -theory of the modi ed tranform H 1 in (5.1.1). First we give the former.
Theorem 5.1. Suppose that (a) < < and that either of conditions (b) a > 0; or (c) a = 0; + Re() 5 0 holds. Then we have the following results: (i) There is a one-to-one transform H 1 2 [L;2; L;2] such that (5:1:11) holds for Re(s) =
and f 2 L;2 . If a = 0; + Re() = 0 and 1 ; 2= EH ; then the transform H 1 maps L;2 onto L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation (5:1:16) holds for H 1. (iii) Let 2 C ; h > 0 and f 2 L;2. When Re() > h ; 1; H 1f is given by
H 1f
(x)
" Z 1 (;; h); (a ; ) i i 1;p x d m;n +1 ( +1) h 1 ; ( +1) =h x H = hx p +1 ;q +1 dx t (bj ; j )1;q ; (; ; 1; h) 0
#
f (t) dt: t
(5.2.1)
When Re() < h ; 1;
H 1f
(x)
Z 1 f (t) dt: (5.2.2) d m+1;n x (ai ; i)1;p; (;; h) ( +1) =h 1 ; ( +1) =h x H = ;hx p +1 ;q +1 dx t 0 (; ; 1; h); (bj ; j )1;q t (iv) The transform H 1 is independent of in the sense that; if and e satisfy (a), and g 1 are de ned in L;2 and L respectively either (b) or (c), and if the transforms H 1 and H e ;2 g 1 1 by (5:1:11); then H f = H f for f 2 L;2 \ Le ;2 . (v) If a > 0 or if a = 0; + Re() < 0; then for f 2 L;2; H 1f is given in (5.1.1). Proof. Due to (5.1.6) and R(L;2) = L1;;2, the results in (i), (iv) and (v) follow by
"
#
virtue of the corresponding statements for the H -transform (3.1.1) given in Theorems 3.6 and 3.7. For \suciently good" functions f and g , (5.1.16) is veri ed directly. In fact, for f 2 L;2 and g 2 L1;;2 it is sucient to show that both sides of (5.1.16) represent bounded linear functionals on L;2 L1;;2 . From (i) and the Schwarz inequality (3.5.6) we have Z
0
1
f (x) H 1g (x)dx =
Z
1 ;1=2 1 = 2 ; 1 [x f (x)][x g (x)]dx
0
5 kf k;2
H
H 1g 1;;2 5 K kf k;2kgk1;;2;
where K is a bound for H 2 [L;2 ]: Hence, the left-hand side in (5.1.16) represents a bounded bilinear functional on L;2 L1;;2 . It is similar for the right side of (5.1.16), which proves (ii). The formulas (5.2.1) and (5.2.2) are proved on the basis of the corresponding representations for the H -transform (3.1.1) given in (3.6.2) and (3.6.3). For f 2 L;2 and Re() > h ; 1, in view of R(L;2 ) = L1;;2 , (5.1.6) and (3.6.2) imply
H 1f
(x) =
H Rf
(x)
Chapter 5. Modi ed H -Transforms on the Space L;r
136
" Z 1 (;; h); (a ; ) i i 1;p d m;n +1 ( +1) =h 1 ; ( +1) =h x H x = hx p +1 ;q +1 (b ; ) dx 0 j j 1;q ; (;1 ; ; h)
#
1 f 1 dt; t t
which yields (5.2.1) after replacing t by 1=t in the integrand. (5.2.2) is proved similarly by using (5.1.6) and (3.6.3). Thus (iii) is established, which completes the proof of the theorem. Now on the basis of the results in Sections 4.1{4.4 and by using (5.1.6) and Lemma 3.1(iii), we present the L;r -theory of the transform H 1 in (5.1.1) when a = 0. From Theorems 4.1{ 4.4 taking into account the isomorphic property R(L;r ) = L1;;r , we obtain the mapping properties and the range of H 1 on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0.
Theorem 5.2. Let a = = 0; Re() = 0; < < and let 1 < r < 1. (a) The transform H 1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;r ]. (b) If 1 < r 5 2; then the transform H 1 is one-to-one on L;r and there holds the equality
(5:1:11) for f 2 L;r and Re(s) = . (c) If f 2 L;r and g 2 L1;;r0 with r0 = r=(r ; 1); then the relation (5:1:16) holds. (d) If 1 ; 2= EH ; then the transform H 1 is one-to-one on L;r and there holds
H 1(L;r ) = L;r : (5.2.3) (e) If f 2 L;r ; 2 C and h > 0; then H 1f is given in (5:2:1) for Re() > h ; 1; while
in (5:2:2) for Re() < h ; 1:
Theorem 5.3. Let a = = 0; Re() < 0; < < ; and let either m > 0 or n > 0.
Let 1 < r < 1. (a) The transform H 1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform H 1 is one-to-one on L;r and there holds the equality (5:1:11) for f 2 L;r and Re(s) = . (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (5:1:16) holds. (d) Let k > 0. If 1 ; 2= EH ; then the transform H 1 is one-to-one on L;r and there hold
H 1 (L;r ) = I;;;k;; =k (L;r )
(5.2.4)
for m > 0; and
; H 1 (L;r ) = I0+; (5.2.5) k; =k;1 (L;r ) for n > 0. When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand sides of (5:2:4) and (5:2:5) in the respective cases. (e) If f 2 L;r ; 2 C and h > 0; then H 1f is given in (5:2:1) for Re() > h ; 1; while in (5:2:2) for Re() < h ; 1. Furthermore H 1 f is given in (5:1:1):
Theorem 5.4. Let a = 0; 6= 0; < < ; 1 < r < 1 and + Re() 5 1=2 ; (r):
Assume that m > 0 if > 0 and n > 0 if < 0.
5.2.
H -Transform on the Space L 1
137
;r
(a) The transform H 1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ]
for all s with r 5 s < 1 such that s0 = [1=2 ; ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H 1 is one-to-one on L;r and there holds the equality (5:1:11) for f 2 L;r and Re(s) = . (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1; 1=r + 1=s = 1 and + Re() 5 1=2 ; max[ (r); (s)]; then the relation (5:1:16) holds. (d) If 1 ; 2= EH ; then the transform H 1 is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there holds
H 1(L;r ) = M=+1=2H ; L1=2;;Re()=;r : (5.2.6) When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5:2:6). (e) If f 2 L;r ; 2 C ; h > 0 and + Re() 5 1=2 ; (r); then H 1f is given in (5:2:1) for Re() > h ; 1; while in (5:2:2) for Re() < h ; 1. If furthermore + Re() < 0; H 1f
is given in (5.1.1).
From Theorem 4.5 we obtain the L;r -theory of the transform H 1 in (5.1.1) with a > 0 in L;r -spaces for any 2 R and 1 5 r 5 1:
Theorem 5.5. Let a > 0; < < and 1 5 r 5 s 5 1: (a) The transform H 1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s].
If 1 5 r 5 2; then H 1 is a one-to-one transform from L;r onto L;s . (b) If f 2 L;r and g 2 L1;;s0 with 1=s + 1=s0 = 1; then the relation (5:1:16) holds.
According to Theorems 4.6{4.10 and the isomorphic property R(L;r ) = L1;;r we characterize the boundedness and the range of H 1 on L;r which will be di erent in ve cases: a1 > 0; a2 > 0; a1 > 0; a2 = 0; a1 = 0; a2 > 0; a > 0; a1 > 0; a2 < 0; and a > 0; a1 < 0; a2 > 0:
Theorem 5.6. Let a1 > 0; a2 > 0; m > 0; n > 0; < < and ! = + a1 ; a2 + 1
and let 1 < r < 1: (a) If 1 ; 2= EH ; or if 1 5 r 5 2; then the transform H 1 is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; 2= EH ; then
H 1(L;r ) =
La1 ; La2 ;1; ;!=a2
(L;r ):
(5.2.7)
When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5:2:7): (c) If Re(!) < 0 and 1 ; 2= EH ; then
H 1(L;r ) =
I;;;1! =a1 ;;a1 La1 ; La2 ;1; (L;r ):
(5.2.8)
When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5.2.8).
Theorem 5.7. Let a1 > 0; a2 = 0; m > 0; < < and ! = + a1 + 1=2 and let
1 < r < 1: (a) If 1 ; 2= EH ; or if 1 < r 5 2; then the transform H 1 is one-to-one on L;r .
Chapter 5. Modi ed H -Transforms on the Space L;r
138
(b) If Re(!) = 0 and 1 ; 2= EH ; then
H 1(L;r ) = La ; ;!=a (L1;;r ): 1
1
When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5:2:9): (c) If Re(!) < 0 and 1 ; 2= EH ; then H 1(L;r ) = I;;;1!=a1;;a1 La1 ; (L1;;r ): When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5.2.10).
(5.2.9) (5.2.10)
Theorem 5.8. Let a1 = 0; a2 > 0; n > 0; < < and ! = ; a2 + 1=2 and let
1 < r < 1: (a) If 1 ; 2= EH ; or if 1 < r 5 2; then the transform H 1 is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; 2= EH ; then H 1(L;r ) = L;a2 ; +!=a2 (L1;;r ): (5.2.11) When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5:2:11): (c) If Re(!) < 0 and 1 ; 2= EH ; then ;! L;a ; (L1;;r ): H 1(L;r ) = I0+;1 (5.2.12) =a2 ;a2 ;1 2 When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5.2.12).
Theorem 5.9. Let a > 0; a1 > 0; a2 < 0; < < and let 1 < r < 1: (a) If 1 ; 2= EH ; or if 1 < r 5 2; then the transform H 1 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
aRe() = (r) ; 2a2 + Re(); Re( ) > ; ; Re( ) < :
(5.2.13) (5.2.14) (5.2.15) (5.2.16)
If 1 ; 2= EH ; then H 1(L;r ) = M1=2+!=(2a2)H ;2a2;2a2 +!;1L;a ;1=2+;!=(2a2) L+1=2+Re(!)=(2a2);r : (5.2.17) When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5.2.17).
Theorem 5.10. Let a > 0; a1 < 0; a2 > 0; < < and let 1 < r < 1: (a) If 1 ; 2= EH ; or if 1 < r 5 2; then the transform H 1 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
aRe() = (r) + 2a1( ; 1) + + Re(); Re( ) > ; 1; Re( ) < 1 ; :
(5.2.18) (5.2.19) (5.2.20) (5.2.21)
5.2.
H -Transform on the Space L 1
139
;r
If 1 ; 2= EH ; then H 1(L;r ) = M;1=2;!=(2a1)H 2a1;2a1+!;1 La;1=2;+!=(2a1) L;1=2;Re(!)=(2a1);r : (5.2.22) When 1 ; 2 EH ; H 1 (L;r ) is a subset of the right-hand side of (5.2.22). To obtain the inversion formulas for the transform H 1 f of (5.1.1) with f 2 L;r ; we note that, in view of (5.1.6) and Lemma 3.1(iii), this transform is just the transform H g of g = Rf 2 L;1;r : H g = H 1f: (5.2.23) Therefore, if a = 0; from (4.9.1) and (4.9.2) we come to the inversion formula for Rf of the form d x(+1)=h Rf (x) = hx1;(+1)=h dx
or
Z
1 q;m;p;n+1 " H p+1;q+1 xt 0
(;; h); (1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i)1;n (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m; (; ; 1; h)
H 1f
(t)dt
#
(5.2.24)
d x(+1)=h Rf (x) = ;hx1;(+1)=h dx
1 q;m+1;p;n H p+1;q+1 0
Z
"
(1 ; ai ; i ; i)n+1;p ; (1 ; ai ; i ; i )1;n; (;; h) xt (; ; 1; h); (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m
H 1f
H 1f
#
(t)dt: (5.2.25) By noting that the operator R;1 ; the inverse to the operator R in (3.3.13), coincides with R; then the directly veri ed relation for D = d=dx and for M given in (3.3.11) RM; DM+1 = ;M +1 DM; R (5.2.26) implies the inversion formulas for the transform H 1 in (1.5.1) in the form d x;(+1)=h f (x) = ;hx(+1)=h dx # " Z 1 (;; h); (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n t q ; m;p ; n +1 H p+1;q+1 x 0 (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m; (; ; 1; h) or
(t)dt
d x;(+1)=h f (x) = hx(+1)=h dx
1 q;m;p;n+1 H p+1;q+1 0
Z
"
(5.2.27)
t (1 ; ai ; i; i)n+1;p ; (1 ; ai ; i ; i)1;n; (;; h) x (; ; 1; h); (1 ; bj ; j ; j )m+1;q; (1 ; bj ; j ; j )1;m
H 1f
(t)dt:
#
(5.2.28)
Chapter 5. Modi ed H -Transforms on the Space L;r
140
The conditions for the validity of (5.2.27) and (5.2.28) follow from Theorems 4.11{4.14 by taking the numbers 0 and 0 in (4.9.6) and (4.9.7). Thus we obtain the following inversion theorems for the transform H 1 in (5.1.1) in the cases when a = 0 and either = 0 or 6= 0.
Theorem 5.11. Let a = 0; < < and 0 < 1 ; < 0; and let 2 C ; h > 0. (a) If + Re() = 0 and f 2 L;2; then the inversion formula (5:2:27) holds for
Re() > (1 ; )h ; 1 and (5:2:28) for Re() < (1 ; )h ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (5:2:27) holds for Re() > (1 ; )h ; 1 and (5:2:28) for Re() < (1 ; )h ; 1.
Theorem 5.12. Let a = 0; 1 < r < 1 and + Re() 5 1=2 ; (r); and let 2 C ;
h > 0.
(a) If > 0; m > 0; < < ; 0 < 1 ; < min[ 0; fRe( + 1=2)=g + 1] and if
f 2 L;r ; then the inversion formulas (5:2:27) and (5:2:28) hold for Re() > (1 ; )h ; 1 and for Re() < (1 ; )h ; 1; respectively. (b) If < 0; n > 0; < < ; max[ 0; fRe( + 1=2)=g + 1] < 1 ; < 0 and if f 2 L;r ; then the inversion formulas (5:2:27) and (5:2:28) hold for Re() > (1 ; )h ; 1 and for Re() < (1 ; )h ; 1; respectively.
5.3. H 2-Transform on the Space L;r
We consider the transform H 2 de ned in (5.1.2). It was shown in Lemma 3.1(iii) that R in (3.3.11) is an isometric isomorphism of L;r onto L1;;r : R(L;r ) = L1;;r . Therefore, as in the previous section, on the basis of (5.1.7) and (5.1.12) we can apply the results for H in Chapters 3 and 4 to obtain the corresponding results for the transform H 2. From Theorems 3.6, 3.7 and 4.1{4.10 we obtain the L;2 - and L;r -theory of the modi ed H -transform H 2 . First we present the former.
Theorem 5.13. Suppose that (a) < 1 ; < and that either of conditions (b) a > 0; or (c) a = 0; (1 ; ) + Re() 5 0 holds. Then we have the following results: (i) There is a one-to-one transform H 22 [L;2; L;2] such that (5:1:12) holds for Re(s) = and f 2 L;2 . If a = 0; (1 ; ) + Re() = 0 and 2= EH ; then the transform H 2 maps L;2 onto L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation (5:1:17) holds for H 2. (iii) Let 2 C ; h > 0 and f 2 L;2: When Re() > (1 ; )h ; 1; H 2f is given by
H 2f
(x)
" # Z 1 (;; h); (a ; ) i i 1;p t d n;m +1 ; ( +1) =h ( +1) =h H f (t)dt: = ;hx dx x 0 q+1;p+1 x (bj ; j )1;q ; (; ; 1; h)
When Re() < (1 ; )h ; 1;
H 2f
(x)
(5.3.1)
5.3.
H -Transform on the Space L 2
141
;r
" Z 1 (a ; ) i i 1;p; (;; h) t d m +1 ;n ; ( +1) =h ( +1) =h x H = hx p +1 ;q +1 dx x (; ; 1; h); (bj; j )1;q 0
#
f (t)dt:
(5.3.2)
(iv) The transform H 2 is independent of in the sense that; if and satisfy (a), and e
either (b) or (c), and if the transforms H 2 and H 2 are de ned in L;2 and Le ;2 respectively g 2 f for f 2 L;2 \ L . by (5:1:12); then H 2 f = H e ;2 (v) If a > 0 or if a = 0; (1 ; ) + Re() < 0; then for f 2 L;2; H 2f is given in (5.1.2). Proof. Statements (i), (iii), (iv) and (v) follow from Theorem 3.6 and 3.7, and we only note that the representations (5.3.1) and (5.3.2) are proved similar to (5.2.27) and (5.2.28) on the basis of the representations (3.6.2) and (3.6.3) by using (5.2.26). (ii) is proved similarly to that in Theorem 5.1. g
Applying the results in Sections 4.1{4.4 by using (5.1.7) and Lemma 3.1(iii) we present the L;r -theory of the transform H 2 in (5.1.2) when a = 0. From Theorems 4.1{4.4 we obtain the mapping properties and the range of H 2 on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0. Note that (5.3.3), (5.3.4), (5.3.5) and (5.3.6) follow from (5.1.7) and (4.1.1), (4.2.1), (4.2.2) and (4.3.1), (4.4.1), if we take into account the isomorphic property R(L;r ) = L1;;r and the relations (3.3.17), (3.3.21) and (3.3.18) in Lemma 3.2.
Theorem 5.14. Let a = = 0; Re() = 0; < 1 ; < and let 1 < r < 1. (a) The transform H 2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;r ]. (b) If 1 < r 5 2; then the transform H 2 is one-to-one on L;r and there holds the equality
(5:1:12) for f 2 L;r and Re(s) = : (c) If f 2 L;r and g 2 L1;;r0 with r0 = r=(r ; 1); then the relation (5:1:17) holds. (d) If 2= EH ; then the transform H 2 is one-to-one on L;r and there holds
H 2(L;r ) = L;r : (5.3.3) (e) If f 2 L;r ; 2 C and h > 0 then H 2f is given in (5:3:1) for Re() > (1 ; )h ; 1;
while in (5:3:2) for Re() < (1 ; )h ; 1:
Theorem 5.15. Let a = = 0; Re() < 0 and < 1 ; < ; and let either m > 0 or
n > 0. Let 1 < r < 1. (a) The transform H 2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform H 2 is one-to-one on L;r and there holds the equality (5:1:12) for f 2 L;r and Re(s) = : (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (5:1:17) holds. (d) Let k > 0. If 2= EH ; then the transform H 2 is one-to-one on L;r and there hold ; H 2 (L;r ) = I0+; k;(1; )=k;1 (L;r )
(5.3.4)
Chapter 5. Modi ed H -Transforms on the Space L;r
142 for m > 0; and
H 2 (L;r ) = I;;;k;( ;1)=k (L;r )
(5.3.5)
for n > 0. When 2 EH ; H 2 (L;r ) is a subset of the right-hand sides of (5:3:4) and (5:3:5) in the respective cases. (e) If f 2 L;r ; 2 C and h > 0; then H 2f is given in (5:3:1) for Re() > (1 ; )h ; 1; while in (5:3:2) for Re() < (1 ; )h ; 1. Furthermore H 2f is given in (5:1:2):
Theorem 5.16. Let a = 0; 6= 0; < 1 ; < ; 1 < r < 1 and (1 ; ) +
Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform H 2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; (1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H 2 is one-to-one on L;r and there holds the equality (5:1:12) for f 2 L;r and Re(s) = : (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1; 1=r +1=s = 1 and (1; )+Re() 5 1=2; max[ (r); (s)]; then the relation (5:1:17) holds. (d) If 2= EH ; then the transform H 2 is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there holds
H 2(L;r ) =
M;=;1=2H ;; L3=2; +Re()=;r :
(5.3.6)
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5:3:6): (e) If f 2 L;r ; 2 C ; h > 0 and (1 ; ) + Re() 5 1=2 ; (r); then H 2f is given in (5:3:1) for Re() > (1 ; )h ; 1; while in (5:3:2) for Re() < (1 ; )h ; 1. If furthermore (1 ; ) + Re() < 0; H 2 f is given in (5.1.2). From Theorem 4.5 we obtain the L;r -theory of the transform H 2 in (5.1.2) with a > 0 in L;r -space for any 2 R and 1 5 r 5 1:
Theorem 5.17. Let a > 0; < 1 ; < and 1 5 r 5 s 5 1: (a) The transform H 2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s].
If 1 5 r 5 2; then H 2 is a one-to-one transform from L;r onto L;s . (b) If f 2 L;r and g 2 L1;;s0 with 1=s + 1=s0 = 1; then the relation (5:1:17) holds.
Due to Theorems 4.6{4.10, we characterize the boundedness and the range of H 2 on L;r which are di erent in ve cases: a1 > 0; a2 > 0; a1 > 0; a2 = 0; a1 = 0; a2 > 0; a > 0; a1 > 0; a2 < 0; and a > 0; a1 < 0; a2 > 0: For these ve cases, such results on the transform H 2 can be obtained by virtue of (5.1.7) and by invoking Theorems 4.6{4.10 and Lemma 3.2. Note that (5.3.7){(5.3.8), (5.3.9){(5.3.10), (5.3.11){(5.3.12) and (5.3.17), (5.3.22) follow from (5.1.7) and (4.6.1){(4.6.2), (4.7.1){(4.7.2), (4.7.15){(4.7.16) and (4.8.5), (4.8.17) in accordance with the isomorphic property R(L;r ) = L1;;r and (3.3.18), (3.3.17) and (3.3.21).
Theorem 5.18. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1; < and ! = +a1 ;a2 +1
and let 1 < r < 1:
5.3.
H -Transform on the Space L 2
143
;r
(a) If 2= EH ; or if 1 5 r 5 2; then the transform H 2 is one-to-one on L;r . (b) If Re(!) = 0 and 2= EH ; then
H 2(L;r ) =
L;a1 ;1; L;a2 ; +!=a2
(L;r ):
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5:3:7): (c) If Re(!) < 0 and 2= EH ; then ;! H 2(L;r ) = I0+;1 L L =a1 ;(1; )a1 ;1 ;a1 ;1; ;a2 ; (L;r ):
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5.3.8).
(5.3.7)
(5.3.8)
Theorem 5.19. Let a1 > 0; a2 = 0; m > 0; < 1 ; < and ! = + a1 + 1=2 and
let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H 2 is one-to-one on L;r . (b) If Re(!) = 0 and 2= EH ; then H 2(L;r ) = L;a1 ;1; +!=a1 (L1;;r ): When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5:3:9): (c) If Re(!) < 0 and 2= EH ; then ;! H 2(L;r ) = I0+;1 L =a1 ;(1; )a1 ;1 ;a1 ;1; (L1;;r ):
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5.3.10).
(5.3.9)
(5.3.10)
Theorem 5.20. Let a1 = 0; a2 > 0; n > 0; < 1 ; < and ! = ; a2 + 1=2 and let
1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H 2 is one-to-one on L;r . (b) If Re(!) = 0 and 2= EH ; then H 2(L;r ) = La2 ;1; ;!=a2 (L1;;r ): When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5:3:11): (c) If Re(!) < 0 and 2= EH ; then H 2(L;r ) = I;;;1!=a2;a2( ;1)La2 ;1; (L1;;r ):
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5.3.12).
(5.3.11)
(5.3.12)
Theorem 5.21. Let a > 0; a1 > 0; a2 < 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H 2 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
aRe() = (r) + 2a2 ( ; 1) + Re(); Re( ) > ; 1; Re( ) < 1 ; :
(5.3.13) (5.3.14) (5.3.15) (5.3.16)
Chapter 5. Modi ed H -Transforms on the Space L;r
144 If 2= EH ; then
H 2(L;r ) =
M;1=2;!=(2a2)H 2a2;2a2 +!;1 La;1=2;+!=(2a2) L ;1=2;Re(!)=(2a2);r : (5.3.17)
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5.3.17).
Theorem 5.22. Let a > 0; a1 < 0; a2 > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EH ; or if 1 < r 5 2; then the transform H 2 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(5.3.18)
aRe() = (r) ; 2a1 + + Re(); Re( ) > ; ; Re( ) < :
(5.3.19) (5.3.20) (5.3.21)
If 2= EH ; then
H 2(L;r ) =
M1=2+!=(2a1)H ;2a1 ;2a1 +!;1 L;a ;1=2+;!=(2a1) L +1=2+Re(!)=(2a1 );r : (5.3.22)
When 2 EH ; H 2(L;r ) is a subset of the right-hand side of (5.3.22).
To obtain the inversion formulas for the transform H 2 when a = 0; we note that (5.1.2) is equivalent to
H f = RH 2f
(f 2 L;r )
(5.3.23)
by virtue of the isometric property R(L;r ) = L1;;r and the fact that the inverse of the operator R;1 of R coincides with R. Then, if a = 0; from the results in Sections 4.9 and 4.10 we obtain the following inversion by replacing H f by RH 2f in (4.9.1) and (4.9.2), and we have d x(+1)=h f (x) = hx1;(+1)=h dx # " Z 1 (;; h); (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n x q ; m;p ; n +1 H p+1;q+1 t (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m; (; ; 1; h) 0 (5.3.24) 1t H 2f (t)dt or d x(+1)=h f (x) = ;hx1;(+1)=h dx # " Z 1 (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n ; (;; h) x q ; m +1 ;p ; n H p+1;q+1 t (; ; 1; h); (1 ; bj ; j ; j )m+1;q; (1 ; bj ; j ; j )1;m 0 (5.3.25) 1t H 2f (t)dt:
5.4.
H ;-Transform on the Space L;r
145
The conditions for the validity of (5.5.27) and (5.5.28) follow from Theorems 4.11{4.14. Thus we obtain the following inversion theorems for the transform H 2 for a = 0 and either = 0 or 6= 0, where 0 and 0 are given in (4.9.6) and (4.9.7).
Theorem 5.23. Let a = 0; < 1 ; < and 0 < < 0; and let 2 C ; h > 0. (a) If (1 ; ) + Re() = 0 and f 2 L;2; then the inversion formula (5:3:24) holds for
Re() > h ; 1 and (5:3:25) for Re() < h ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (5:3:24) holds for Re() > h ; 1 and (5:3:25) for Re() < h ; 1.
Theorem 5.24. Let a = 0; 1 < r < 1 and (1 ; ) + Re() 5 1=2 ; (r); and let
2 C ; h > 0. (a) If > 0; m > 0; < 1 ; < ; 0 < < min[ 0; fRe( + 1=2)=g + 1] and if f 2 L;r ; then the inversion formulas (5:3:24) and (5:3:25) hold for Re() > h ; 1 and for Re() < h ; 1; respectively. (b) If < 0; n > 0; < 1 ; < ; max[ 0; fRe( + 1=2)=g + 1] < < 0 and if f 2 L;r ; then the inversion formulas (5:3:24) and (5:3:25) hold for Re() > h ; 1 and for Re() < h ; 1; respectively.
5.4. H ; -Transform on the Space L;r
We proceed to the transform H ; de ned in (5.1.3). Due to Lemma 3.1(i), M is an isometric isomorphism of L;r onto L ;Re();r :
M (L;r ) = L;Re();r :
(5.4.1)
Therefore (5.1.8) and (5.1.13) show that we can apply the results which were proved in Chapters 3 and 4 for the transform H , by replacing by ; Re() to obtain the corresponding results for the transform H ; . From Theorems 3.6, 3.7 and 4.1 - 4.10 we obtain the L;2 - and L;r -theory of the modi ed tranform H ; . First we give the former.
Theorem 5.25. Suppose that (a) < 1 ; + Re() < and that either of conditions (b) a > 0; or (c) a = 0; [1 ; + Re()] + Re() 5 0 holds. Then we have the following
results:
(i) There is a one-to-one transform H ; 2 [L;2; L1;+Re(;);2] such that (5:1:13) holds
for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . If a = 0; [1 ; + Re()] + Re() = 0 and ; Re() 2= EH ; then the transform H ; maps L;2 onto L1;+Re(;);2. (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation (5:1:18) holds for H ;. (iii) Let 2 C ; h > 0 and f 2 L;2: When Re() > [1 ; + Re()]h ; 1; H ;f is given by H ;f (x) = hx+1;(+1)=h dxd x(+1)h
Chapter 5. Modi ed H -Transforms on the Space L;r
146
1 m;n+1 H 0 p+1;q+1
Z
"
# (;; h); (ai; i)1;p xt tf (t)dt: (bj ; j )1;q ; (; ; 1; h)
(5.4.2)
When Re() < [1 ; + Re()]h ; 1;
H ;f
d x(+1)=h (x) = ;hx+1;(+1)=h dx
1 m+1;n H 0 p+1;q+1
Z
"
# (ai ; i)1;p; (;; h) tf (t)dt: xt (; ; 1; h); (bj ; j )1;q
(5.4.3)
(iv) The transform H ; is independent of in the sense that; if and satisfy (a), and e
(b) or (c), and if the transforms H ; and H ; are de ned in L;2 and Le ;2 respectively by f (5:1:13); then H ; f = H ; f for f 2 L;2 \ Le ;2. (v) If a > 0 or if a = 0; [1 ; + Re()] + Re() < 0; then for f 2 L;2; H ;f is given in (5.1.3). Proof. Statements (i), (iii), (iv) and (v) follow from Theorems 3.6 and 3.7 on the basis of the relations (5.1.8) and (5.1.13) and the isometric property (5.4.1). (ii) is proved similarly to that in Theorem 5.1 by using the Schwartz inequality (3.5.6). Now the results in Sections 4.1{4.4, (1.5.7) and Lemma 3.1(i) yield the L;r -theory of the transform H ; in (5.1.3) when a = 0. From Theorems 4.1{4.4, we obtain the mapping properties and the range of H ; on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0. Note that the relations (5.4.5), (5.4.6) and (5.4.7) below follow from (4.2.1), (4.2.2) and (4.3.1), (4.4.1) taking into account (5.1.8), (5.4.1) and Lemma 3.2 for the Erdelyi{Kober type fractional integration operators I0+; ; and I;;; . f
Theorem 5.26. Let a = = 0; Re() = 0; < 1 ; + Re() < and let 1 < r < 1. (a) The transform H ; de ned on L;2 can be extended to L;r as an element of
[L;r ; L1; +Re(;);r ]. (b) If 1 < r 5 2; then the transform H ; is one-to-one on L;r and there holds the equality (5:1:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ): (c) If f 2 L;r and g 2 L+Re(;);r0 with r0 = r=(r ; 1); then the relation (5:1:18) holds. (d) If ; Re() 2= EH ; then the transform H ; is one-to-one on L;r and there holds
(e) If f 2 L;r ; 2 C
H ;(L;r ) = L1;+Re(;);r : (5.4.4) and h > 0; then H ; f is given in (5:4:2) for Re() > [1 ; +
Re()]h ; 1; while in (5:4:3) for Re() < [1 ; + Re()]h ; 1:
Theorem 5.27. Let a = = 0; Re() < 0 and < 1 ; + Re() < ; and let either
m > 0 or n > 0. Let 1 < r < 1. (a) The transform H ; de ned on L;2 can be extended to L;r as an element of [L;r ; L1; +Re(;);s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform H ; is one-to-one on L;r and there holds the equality (5:1:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ):
5.4.
H ;-Transform on the Space L;r
147
(c) If f 2 L;r and g 2 L+Re(;);s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re();
then the relation (5:1:18) holds. (d) Let k > 0. If ; Re() 2= EH ; then the transform H ; is one-to-one on L;r and there hold
H ; (L;r ) = I;;;k;(; )=k
L1; +Re(;);r
(5.4.5)
for m > 0; and ; H ; (L;r ) = I0+; (5.4.6) k;( ;)=k;1 L1; +Re(;);r for n > 0. When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand sides of (5:4:5) and (5:4:6) in the respective cases. (e) If f 2 L;r ; 2 C and h > 0; then H ; f is given in (5:4:2) for Re() > [1 ; + Re()]h ; 1; while in (5:4:3) for Re() < [1 ; + Re()]h ; 1. Furthermore H ; f is given in
(5.1.3).
Theorem 5.28. Let a = 0; 6= 0; < 1 ; + Re() < ; 1 < r < 1 and [1 ; +
Re()] + Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform H ; de ned on L;2 can be extended to L;r as an element of [L;r ; L1; +Re(;);s ] for all s with r 5 s < 1 such that s0 = [1=2;f1; +Re()g;Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H ; is one-to-one on L;r and there holds the equality (5:1:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ): (c) If f 2 L;r and g 2 L+Re(;);s with 1 < s < 1; 1=r +1=s = 1 and [1 ; +Re()]+ Re() 5 1=2 ; max[ (r); (s)]; then the relation (5:1:18) holds. (d) If ; Re() 2= EH ; then the transform H ; is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re() > ;1 and there holds
H ; (L;r ) = M+=+1=2 H ; L;1=2;Re()=;Re();r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5:4:7).
(5.4.7)
(e) If f 2 L;r ; 2 C ; h > 0 and [1 ; + Re()] + Re() 5 1=2 ; (r); then H ;f is
given in (5:4:2) for Re() > [1 ; +Re()]h ; 1; while in (5:4:3) for Re() < [1 ; +Re()]h ; 1. If [1 ; + Re()] + Re() < 0; H ; f is given in (5.1.3).
According to (5.1.8) and (5.4.1), Theorem 4.5 deduces the L;r -theory of the transform H ; in (5.1.3) with a > 0 in L;r -spaces for any 2 R and 1 5 r 5 1:
Theorem 5.29. Let a > 0; < 1 ; + Re() < and 1 5 r 5 s 5 1: (a) The transform H ; de ned on L;2 can be extended to L;r as an element of
[L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then H ; is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If f 2 L;r and g 2 L+Re(;);s0 with 1=s +1=s0 = 1; then the relation (5:1:18) holds.
Chapter 5. Modi ed H -Transforms on the Space L;r
148
Due to (5.1.8) and (5.4.1), Theorems 4.6{4.10 and Lemma 3.2, we may characterize the boundedness and the range of H ; on L;r which will be di erent in various combinations of signs of a ; a1 and a2:
Theorem 5.30. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; + Re() < and
! = + a1 ; a2 + 1 and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 5 r 5 2; then the transform H ; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EH ; then
H ;(L;r ) = La ; ; La ;1; +;!=a L1;+Re(;);r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5:4:8):
(5.4.8)
H ;(L;r ) = I;;;1!=a ;a (; )La ; ; La ;1; + L1;+Re(;);r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5.4.9).
(5.4.9)
1
2
2
(c) If Re(!) < 0 and ; Re() 2= EH ; then
1
1
1
2
Theorem 5.31. Let a1 > 0; a2 = 0; m > 0; < 1 ; +Re() < and ! = + a1 +1=2
and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H ; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EH ; then
H ; (L;r ) = La ; ;;!=a L;Re(;);r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5:4:10):
(5.4.10)
H ;(L;r ) = I;;;1!=a ;a (; )La ; ; L;Re(;);r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5.4.11).
(5.4.11)
1
1
(c) If Re(!) < 0 and ; Re() 2= EH ; then
1
1
1
Theorem 5.32. Let a1 = 0; a2 > 0; n > 0; < 1 ; + Re() < and ! = ; a2 + 1=2
and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H ; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EH ; then
H ; (L;r ) = L;a ; ;+!=a L;Re(;);r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5:4:12):
(5.4.12)
;! H ;(L;r ) = I0+;1 =a ;a ( ;);1 L;a ; ; L ;Re(;);r : When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5.4.13).
(5.4.13)
2
2
(c) If Re(!) < 0 and ; Re() 2= EH ; then
2
2
2
Theorem 5.33. Let a > 0; a1 > 0; a2 < 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H ; is one-to-one on L;r .
5.4.
H ;-Transform on the Space L;r
149
(b) Let !; ; 2 C be chosen as
! = a ; ; 21 ;
(5.4.14)
aRe() = (r) + 2a2[ ; Re() ; 1] + Re(); Re( ) > ; Re() ; 1; Re( ) < 1 ; + Re(): If ; Re() 2= EH ; then H ; (L;r ) = M+1=2+!=(2a2 )H ;2a2 ;2a2+!;1L;a;1=2+;!=(2a2)
(5.4.15) (5.4.16) (5.4.17)
L3=2; +Re(!)=(2a2);Re();r :
When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5.4.18).
(5.4.18)
Theorem 5.34. Let a > 0; a1 < 0; a2 > 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H ; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(5.4.19)
aRe( ) = (r) ; 2a1 [ ; Re()] + + Re(); Re( ) > ; + Re(); Re( ) < ; Re(): If ; Re() 2= EH ; then H ; (L;r ) = M;1=2;!=(2a1 )H 2a1;2a1+!;1 La;1=2;+!=(2a1)
(5.4.20) (5.4.21) (5.4.22)
L1=2; ;Re(!)=(2a1);Re();r :
When ; Re() 2 EH ; H ; (L;r ) is a subset of the right-hand side of (5.4.23).
(5.4.23)
The relation (5.1.8) and Lemma 3.1(i) imply that (5.1.3) is equaivalent to H M f = M; H ; by taking into account the isometric property (5.4.1) and the relation M;1 = M; : (5.4.24) Thus, if a = 0; from the results of Sections 4.9 and 4.10 by applying (4.9.1), (4.9.2) and (5.4.24), we obtain the inversion formulas for the transform H ; in the form d x(+1)=h f (x) = hx1;;(+1)=h dx " # Z 1 (;; h); (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i )1;n q ; m;p ; n +1 H p+1;q+1 xt 0 (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m ; (; ; 1; h)
t;
H ; f
(t)dt
(5.4.25)
Chapter 5. Modi ed H -Transforms on the Space L;r
150 or
d x(+1)=h f (x) = ;hx1;;(+1)=h dx
1 q;m+1;p;n " H p+1;q+1 xt 0
Z
(1 ; ai ; i ; i )n+1;p; (1 ; ai ; i ; i )1;n; (;; h) (; ; 1; h); (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m
t;
H ; f
#
(t)dt: (5.4.26) The conditions for the validity of (5.4.25) and (5.4.26) follow from Theorems 4.11{4.14 and we obtain the following inversion theorems for the transform H 1 in the cases when a = 0 and either = 0 or 6= 0.
Theorem 5.35. Let a = 0; < 1 ; + Re() < and 0 < ; Re() < 0; and let
2 C ; h > 0. (a) If [1 ; + Re()] + Re() = 0 and f 2 L;2; then the inversion formula (5:4:25) holds for Re() > [ ; Re()]h ; 1 and (5:4:26) for Re() < [ ; Re()]h ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (5:4:25) holds for Re() > [ ; Re()]h ; 1 and (5:4:26) for Re() < [ ; Re()]h ; 1.
Theorem 5.36. Let a = 0; 1 < r < 1 and [1 ; + Re()] + Re() 5 1=2 ; (r); and
let 2 C ; h > 0. (a) If > 0; m > 0; < 1 ; + Re() < ; 0 < ; Re() < min[ 0; fRe( + 1=2)=g + 1] and if f 2 L;r ; then the inversion formulas (5:4:25) and (5:4:26) hold for Re() > [ ; Re()]h ; 1 and for Re() < [ ; Re()]h ; 1; respectively. (b) If < 0; n > 0; < 1 ; + Re() < ; max[ 0; fRe( + 1=2)=g + 1] < ; Re() < 0 and if f 2 L;r ; then the inversion formulas (5:4:25) and (5:4:26) hold for Re() > [ ; Re()]h ; 1 and for Re() < [ ; Re()]h ; 1; respectively.
Remark 5.2. The results in this section generalize those in Sections 3.6 and 4.1{4.10. In
fact, when = = 0; Theorems 3.6 and 3.7 follow from Theorem 5.25, Theorems 4.1 and 4.2 from Theorems 5.26 and 5.27, Theorems 4.3 and 4.4 from Theorem 5.28, Theorems 4.5{4.10 from Theorems 5.29{5.34, Theorems 4.11 and 4.12 from Theorem 5.35, and Theorems 4.13 and 4.14 from Theorem 5.36.
5.5. H 1; -Transform on the Space L;r
Now we proceed to the transform H 1; de ned in (5.1.4). In view of (5.1.9) this transform is connected with the transform H 1 via the elementary operators M and M in the same way as the H ; in (5.1.3) is connected with the H -transform in (3.1.1). Therefore by virtue of (5.1.9) and the isometric property (5.4.1), we apply the results in Section 5.2 for the transform H 1 by replacing by ; Re():
Theorem 5.37. Suppose that (a) < ; Re() < and that either of conditions (b) (c) a = 0; [ ; Re()] + Re() 5 0 holds. Then we have the following results:
a > 0; or
5.5.
H ;-Transform on the Space L;r
151
1
(i) There is a one-to-one transform H 1; 2 [L;2; L;Re(+);2] such that (5:1:14) holds for
Re(s) = ; Re( + ) and f 2 L;2 . If a = 0; [ ; Re()]+Re() = 0 and 1 ; +Re() 2= EH ; then the transform H 1; maps L;2 onto L ;Re(+);2 . (ii) If f 2 L;2 and g 2 L1;+Re(+);2; then the relation (5:1:19) holds for H 1;. (iii) Let 2 C ; h > 0 and f 2 L;2: When Re() > [ ; Re()]h ; 1; H 1;f is given by
H 1; f
d x(+1)h (x) = hx+1;(+1)=h dx
1 m;n+1 " x H 0 p+1;q+1 t
Z
# (;; h); (ai; i)1;p t;1 f (t)dt: (bj ; j )1;q ; (; ; 1; h)
(5.5.1)
When Re() < [ ; Re()]h ; 1;
H 1; f
d x(+1)=h (x) = ;hx+1;(+1)=h dx
1 m+1;n " x H 0 p+1;q+1 t
Z
# (ai ; i )1;p; (;; h) t;1 f (t)dt: (; ; 1; h); (bj; j )1;q
(5.5.2)
(iv) The transform H 1; is independent of in the sense that, if and satisfy (a), e
g 1 ; are de ned in L;2 and L and either (b) or (c), and if the transforms H 1; and H ;2 e g 1 1 respectively by (5:1:14); then H ; f = H ; f for f 2 L;2 \ Le ;2. (v) If a > 0 or if a = 0; [ ; Re()] + Re() < 0; then for f 2 L;2; H 1; f is given
in (5.1.4).
We now present the L;r -theory of the transform H 1; when a = 0 by virtue of the results in Section 5.2, (5.1.9) and Lemmas 3.1(i) and 3.2. From Theorems 5.2{5.4 we deduce the mapping properties and the range of H 1; on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0.
Theorem 5.38. Let a = = 0; Re() = 0; < ; Re() < and let 1 < r < 1. (a) The transform H 1; de ned on L;2 can be extended to L;r as an element of
[L;r ; L ;Re(+);r ]. (b) If 1 < r 5 2; then the transform H 1; is one-to-one on L;r and there holds the equality (5:1:14) for f 2 L;r and Re(s) = ; Re( + ): (c) If f 2 L;r and g 2 L1;+Re(+);r0 with r0 = r=(r ; 1); then the relation (5:1:19) holds. (d) If 1 ; + Re() 2= EH ; then the transform H 1; is one-to-one on L;r and there holds
H 1; (L;r ) = L;Re(+);r : (5.5.3) (e) If f 2 L;r ; 2 C and h > 0; then H 1;f is given in (5:5:1) for Re() > [ ;Re()]h;1;
while in (5:5:2) for Re() < [ ; Re()]h ; 1:
Theorem 5.39. Let a = = 0; Re() < 0; < ; Re() < ; and let either m > 0 or
n > 0. Let 1 < r < 1.
Chapter 5. Modi ed H -Transforms on the Space L;r
152
(a) The transform H 1; de ned on
L;2 can be extended to L;r as an element of
[L;r ; L ;Re(+);s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform H 1; is one-to-one on L;r and there holds the equality (5:1:14) for f 2 L;r and Re(s) = ; Re( + ): (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (5:1:19) holds. (d) Let k > 0. If 1 ; + Re() 2= EH ; then the transform H 1; is one-to-one on L;r and there hold for m > 0; and
H 1; (L;r ) = I;;;k;(; )=k
L ;Re(+);r
(5.5.4)
; H 1; (L;r ) = I0+; (5.5.5) k;( ;)=k;1 L ;Re(+);r for n > 0. When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand sides of (5:5:4) and (5:5:5) in the respective cases. (e) If f 2 L;r ; 2 C and h > 0; then H 1;f is given in (5:5:1) for Re() > [ ;Re()]h;1; while in (5:5:2) for Re() < [ ; Re()]h ; 1. Furthermore H 1; f is given in (5.1.4).
Theorem 5.40. Let a = 0; 6= 0; < ; Re() < ; 1 < r < 1 and [ ; Re()] +
Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform H 1; de ned on L;2 can be extended to L;r as an element of [L;r ; L ;Re(+);s ] for all s with r 5 s < 1 such that s0 = [1=2 ; f ; Re()g ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H 1; is one-to-one on L;r and there holds the equality (5:1:14) for f 2 L;r and Re(s) = ; Re( + ): (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1; 1=r + 1=s = 1 and [ ; Re()] + Re() 5 1=2 ; max[ (r); (s)]; then the relation (5:1:19) holds. (d) If 1 ; + Re() 2= EH ; then the transform H 1; is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re() > ;1 and there hold
H 1; (L;r ) = M+=+1=2 H ; L1=2;;Re()=;Re();r : (5.5.6) When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5:5:6): (e) If f 2 L;r ; 2 C ; h > 0 and [ ; Re()] + Re() 5 1=2 ; (r); then H 1; f is given in (5:5:1) for Re() > [ ; Re()]h ; 1; while in (5:5:2) for Re() < [ ; Re()]h ; 1. If [ ; Re()] + Re() < 0; H 1; f is given in (5.1.4). From (5.1.9), (5.4.1) and Theorem 5.5, the L;r -theory of the transform H 1; in (5.1.4)
with a > 0 in L;r -space can be established for any 2 R and 1 5 r 5 1:
Theorem 5.41. Let a > 0; < ; Re() < and 1 5 r 5 s 5 1: (a) The transform H 1; de ned on L;2 can be extended to L;r as an element of [L;r ;
L ;Re(+);s ]. If 1 5 r 5 2; then H 1; is a one-to-one transform from L;r onto L ;Re(+);s . (b) If f 2 L;r and g 2 L1;+Re(+);s0 with 1=s+1=s0 = 1; then the relation (5:1:19) holds.
5.5.
H ;-Transform on the Space L;r
153
1
By virtue of (5.1.9), (5.4.1), Theorems 5.6{5.10 and Lemma 3.2 we characterize the boundedness and the range of H 1; on L;r for a > 0 in ve cases.
Theorem 5.42. Let a1 > 0; a2 > 0; m > 0; n > 0; < ; Re() < and
! = + a1 ; a2 + 1 and let 1 < r < 1: (a) If 1 ; + Re() 2= EH ; or if 1 5 r 5 2; then the transform H 1; is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; + Re() 2= EH ; then
H 1; (L;r ) = La ; ; La ;1; +;!=a L;Re(+);r : When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5:5:7):
1
2
2
(5.5.7)
(c) If Re(!) < 0 and 1 ; + Re() 2= EH ; then
H 1; (L;r ) =
I;;;1!=a1 ;a1 (; )La1 ; ; La2 ;1; + L;Re(+);r :
(5.5.8)
When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5.5.8).
Theorem 5.43. Let m > 0; a1 > 0; a2 = 0; < ; Re() < and ! = + a1 + 1=2
and let 1 < r < 1: (a) If 1 ; + Re() 2= EH ; or if 1 < r 5 2; then the transform H 1; is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; + Re() 2= EH ; then
H 1;(L;r ) = La ; ;;!=a L1;+Re(+);r : When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5:5:9):
(5.5.9)
H 1; (L;r ) = I;;;1!=a ;a (; )La ; ; L1;+Re(+);r : When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5.5.10).
(5.5.10)
1
1
(c) If Re(!) < 0 and 1 ; + Re() 2= EH ; then
1
1
1
Theorem 5.44. Let a1 = 0; a2 > 0; n > 0; < ; Re() < and ! = ; a2 + 1=2
and let 1 < r < 1: (a) If 1 ; + Re() 2= EH ; or if 1 < r 5 2; then the transform H 1; is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; + Re() 2= EH ; then
H 1;(L;r ) = L;a ; ;+!=a L1;+Re(+);r : When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5:5:11):
2
2
(5.5.11)
(c) If Re(!) < 0 and 1 ; + Re() 2= EH ; then
H 1; (L;r ) =
;! I0+;1 =a2 ;a2 ( ;);1L;a2 ; ; L1; +Re(+);r :
(5.5.12)
When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5.5.12).
Theorem 5.45. Let a > 0; a1 > 0; a2 < 0; < ; Re() < and let 1 < r < 1: (a) If 1 ; + Re() 2= EH ; or if 1 < r 5 2; then the transform H 1; is one-to-one on L;r .
Chapter 5. Modi ed H -Transforms on the Space L;r
154
(b) Let !; ; 2 C be chosen as
! = a ; ; 21 ;
(5.5.13)
a Re() = (r) + 2a2 [ ; Re()] + Re(); Re( ) > ; + Re(); Re( ) < ; Re(): If 1 ; + Re() 2= EH ; then H 1; (L;r ) = M+1=2+!=(2a2 )H ;2a2 ;2a2+!;1L;a;1=2+;!=(2a2)
(5.5.14) (5.5.15) (5.5.16)
L +1=2+Re(!)=(2a2);Re();r :
When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5.5.17).
(5.5.17)
Theorem 5.46. Let a > 0; a1 < 0; a2 > 0; < ; Re() < and let 1 < r < 1: (a) If 1 ; + Re() 2= EH ; or if 1 < r 5 2; then the transform H 1; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(5.5.18)
aRe( ) = (r) ; 2a1 [ ; Re()] + + Re(); Re( ) > ; + Re(); Re( ) < ; Re(): If 1 ; + Re() 2= EH ; then H 1; (L;r ) = M;1=2;!=(2a1 )H 2a1;2a1+!;1 La;1=2;+!=(2a1)
(5.5.19) (5.5.20) (5.5.21)
L ;1=2;Re(!)=(2a1);Re();r :
When 1 ; + Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5.5.22).
(5.5.22)
The inversion formulas for the transform H 1; can be found in a similar manner as before by only noting that (5.1.4) is equaivalent to
H 1Mf = M; H 1; f
for f 2 L;r . Thus by virtue of (5.2.27) and (5.2.28) we have formally that d x;(+1)=h f (x) = ;hx(+1)=h; dx " Z 1 (;; h); (1 ; a ; ; ) i i i n+1;p ; (1 ; ai ; i ; i)1;n t q ; m;p ; n +1 H p+1;q+1 x 0 (1 ; bj ; j ; j )m+1;q ; (1 ; bj ; j ; j )1;m; (; ; 1; h)
t;
H 1; f
(t)dt
#
(5.5.23)
5.6.
H ;-Transform on the Space L;r
155
2
or
d x;(+1)=h f (x) = hx(+1)=h; dx
Z
1 q;m+1;p;n H p+1;q+1 0
"
t (1 ; ai ; i; i)n+1;p ; (1 ; ai ; i ; i)1;n; (;; h) x (; ; 1; h); (1 ; bj ; j ; j )m+1;q; (1 ; bj ; j ; j )1;m
t;
H 1; f
(t)dt:
#
(5.5.24)
The conditions for the validity of (5.5.23) and (5.5.24) follow from Theorems 5.11{5.12.
Theorem 5.47. Let a = 0; < ; Re() < and 0 < 1 ; + Re() < 0; and let
2 C ; h > 0. (a) If [ ; Re()] + Re() = 0 and f 2 L;2 ; then the inversion formula (5:5:23) holds for Re() > [1 ; + Re()]h ; 1 and (5:5:24) for Re() < [1 ; + Re()]h ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (5:5:23) holds for Re() > [1 ; + Re()]h ; 1 and (5:5:24) for Re() < [1 ; + Re()]h ; 1.
Theorem 5.48. Let a = 0; 1 < r < 1 and [ ; Re()] + Re() 5 1=2 ; (r); and let
2 C ; h > 0. (a) If > 0; m > 0; < ;Re() < ; 0 < 1; +Re() < min[ 0; fRe(+1=2)=g+1] and if f 2 L;r ; then the inversion formulas (5:5:23) and (5:5:24) hold for Re() > [1 ; + Re()]h ; 1 and for Re() < [1 ; + Re()]h ; 1; respectively. (b) If < 0; n > 0; < ;Re() < ; max[ 0; fRe(+1=2)=g+1] < 1; +Re() < 0 and if f 2 L;r ; then the inversion formulas (5:5:23) and (5:5:24) hold for Re() > [1 ; + Re()]h ; 1 and for Re() < [1 ; + Re()]h ; 1; respectively.
Remark 5.3. The results in this section generalize those in Section 5.2. Namely, Theorems 5.1{5.12 follow from Theorems 5.37{5.48 when = = 0: 5.6. H 2; -Transform on the Space L;r
Finally, let us study the transform H 2; de ned in (5.1.5). According to (5.1.10) this transform is connected with the transform H 2 via the elementary operators M and M in the same way as the H 1; in (5.1.4) is connected with the H 1. Therefore by using (5.1.10) and the isometric property (5.4.1), we can apply the results in Section 5.3 for the transform H 2f by replacing by ; Re().
Theorem 5.49. Suppose that (a) < 1 ; + Re() < and that either of the conditions (b) a > 0; or (c) a = 0; [1 ; + Re()] + Re() 5 0 holds. Then we have the following results:
156
Chapter 5. Modi ed H -Transforms on the Space L;r
(i) There is a one-to-one transform H 2;2 [L;2; a
L ;Re(+);2 ] such that (5:1:15) holds
for Re(s) = ; Re( + ) and f 2 L;2 . If = 0; [1 ; + Re()] + Re() = 0 and ; Re() 2= EH ; then the transform H 2; maps L;2 onto L;Re(+);2 . (ii) If f 2 L;2 and g 2 L1;+Re(+);2; then the relation (5:1:20) holds for H 2;. (iii) Let 2 C ; h > 0 and f 2 L;2: When Re() > [1 ; + Re()]h ; 1; H 2;f is given by H 2;f (x) = ;hx+(+1)=h dxd x;(+1)h # " Z 1 (;; h); (a ; ) i i 1;p t m;n +1 t f (t)dt: (5.6.1) H 0 p+1;q+1 x (bj ; j )1;q ; (; ; 1; h) When Re() < [1 ; + Re()]h ; 1; H 2;f (x) = hx+(+1)=h dxd x;(+1)=h # " Z 1 (a ; ) i i 1;p; (;; h) t m +1 ;n t f (t)dt: (5.6.2) H 0 p+1;q+1 x (; ; 1; h); (bj ; j )1;q
(iv) The transform H 2; is independent of in the sense that; if and satisfy (a), e
and either (b) or (c), and if the transforms H 2; and H 2 ; are de ned in L;2 and Le ;2 g 2 ; f for f 2 L;2 \ L . respectively by (5:1:15); then H 2; f = H e ;2 (v) If a > 0 or if a = 0; [1 ; + Re()] + Re() < 0; then for f 2 L;2; H 2;f is given in (5.1.5). g
The results in Section 5.3 deduce the L;r -theory of the transform H 2; when a = 0 by virtue of (5.1.10), (5.4.1) and Lemmas 3.1(i) and 3.2.
Theorem 5.50. Let a = = 0; Re() = 0; < 1 ; + Re() < and let 1 < r < 1: (a) The transform H 2; de ned on L;2 can be extended to L;r as an element of
[L;r ; L ;Re(+);r ]. (b) If 1 < r 5 2; then the transform H 2; is one-to-one on L;r and there holds the equality (5:1:15) for f 2 L;r and Re(s) = ; Re( + ): (c) If f 2 L;r and g 2 L1;+Re(+);r0 with r0 = r=(r ; 1); then the relation (5:1:20) holds. (d) If ; Re() 2= EH ; then the transform H 2; is one-to-one on L;r and there holds
H 2; (L;r ) = L;Re(+);r : (5.6.3) and h > 0; then H 2; f is given in (5:6:1) for Re() > [1 ; +
(e) If f 2 L;r ; 2 C Re()]h ; 1; while in (5:6:2) for Re() < [1 ; + Re()]h ; 1:
Theorem 5.51. Let a = = 0; Re() < 0 and < 1 ; + Re() < ; and let either
m > 0 or n > 0. Let 1 < r < 1. (a) The transform H 2; de ned on L;2 can be extended to L;r as an element of [L;r ; L ;Re(+);s ] for all s = r such that 1=s > 1=r + Re().
5.6.
H ;-Transform on the Space L;r
157
2
(b) If 1 < r 5 2; then the transform H 2; is one-to-one on L;r and there holds the
equality (5:1:15) for f 2 L;r and Re(s) = ; Re( + ): (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (5:1:20) holds. (d) Let k > 0. If ; Re() 2= EH ; then the transform H 2; is one-to-one on L;r and there hold ; H 2; (L;r ) = I0+; k;(1; ;)=k;1
L ;Re(+);r
(5.6.4)
for m > 0; and
H 2; (L;r ) = I;;;k;( +;1)=k L;Re(+);r (5.6.5) for n > 0. When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand sides of (5:6:4) and (5:6:5) in the respective cases. (e) If f 2 L;r ; 2 C and h > 0; then H 2; f is given in (5:6:1) for Re() > [1 ; + Re()]h ; 1; while in (5:6:2) for Re() < [1 ; + Re()]h ; 1. Furthermore H 2; f is given in
(5:1:5):
Theorem 5.52. Let a = 0; 6= 0; m > 0; < 1 ; + Re() < ; 1 < r < 1 and
[1 ; + Re()] + Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform H 2; de ned on L;2 can be extended to L;r as an element of [L;r ; L ;Re(+);s ] for all s with r 5 s < 1 such that s0 = [1=2 ; f1 ; +Re()g; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; the transform H 2; is one-to-one on L;r and there holds the equality (5:1:15) for f 2 L;r and Re(s) = ; Re( + ): (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1; 1=r + 1=s = 1 and [ ; Re()] + Re() 5 1=2 ; max[ (r); (s)]; then the relation (5:1:20) holds. (d) If ; Re() 2= EH ; then the transform H 2; is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re() > ;1 and there holds
H 2; (L;r ) = M;=;1=2H;; L3=2;+Re()=+Re();r : When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5:6:6):
(5.6.6)
(e) If f 2 L;r ; 2 C ; h > 0 and [1 ; + Re()] + Re() 5 1=2 ; (r); then H 2; f is
given in (5:6:1) for Re() > [1 ; +Re()]h ; 1; while in (5:6:2) for Re() < [1 ; +Re()]h ; 1. If [1 ; + Re()] + Re() < 0; H 2; f is given in (5.1.5).
From (5.1.10), (5.4.1) and Theorem 5.5, the L;r -theory of the transform H 2; in (5.1.5) with a > 0 in L;r -space can be established for any 2 R and 1 5 r 5 1:
Theorem 5.53. Let a > 0; < 1 ; + Re() < and 1 5 r 5 s 5 1: (a) The transform H 2; de ned on L;2 can be extended to L;r as an element of
[L;r ; L ;Re(+);s ]. If 1 5 r 5 2; then L1; +Re(+);s .
H 2;
is a one-to-one transform from L;r onto
Chapter 5. Modi ed H -Transforms on the Space L;r
158
(b) If f 2 L;r and g 2 L1;+Re(+);s0 with 1=s+1=s0 = 1; then the relation (5:1:20) holds. By virtue of (5.1.10), (5.4.1), Theorems 5.18{5.22 and Lemma 3.2 we characterize the boundedness and the range of H 2; on L;r for a > 0.
Theorem 5.54. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; + Re() < and
! = + a1 ; a2 + 1 and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 5 r 5 2; then the transform H 2; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EH ; then
H 2;(L;r ) = L;a ;1; ; L;a ; ++!=a L;Re(+);r : When ; Re() 2 EH ; H 1; (L;r ) is a subset of the right-hand side of (5:6:7):
1
2
2
(5.6.7)
(c) If Re(!) < 0 and ; Re() 2= EH ; then
H 2; (L;r ) =
;! I0+;1 =a1 ;a1 (1;; );1 L;a1 ;1; ; L;a2 ; + L ;Re(+);r :
(5.6.8)
When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5.6.8).
Theorem 5.55. Let a1 > 0; a2 = 0; m > 0; < 1 ; +Re() < and ! = + a1 +1=2
and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H 2; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EH ; then
H 2; (L;r ) = L;a ;1; ;+!=a L1;+Re(+);r : When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5:6:9):
(5.6.9)
;! H 2;(L;r ) = I0+;1 =a ;a (1;; );1 L;a ;1; ; L1; +Re(+);r : When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5.6.10).
(5.6.10)
1
1
(c) If Re(!) < 0 and ; Re() 2= EH ; then
1
1
1
Theorem 5.56. Let a1 = 0; a2 > 0; n > 0; < 1 ; + Re() < and ! = ; a2 + 1=2
and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H 2; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EH ; then
H 2; (L;r ) = La ;1; ;;!=a L1;+Re(+);r : When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5:6:11):
(5.6.11)
H 2; (L;r ) = I;;;1!=a ;a ( +;1)La ;1; ; L1;+Re(+);r : When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5.6.12).
(5.6.12)
2
2
(c) If Re(!) < 0 and ; Re() 2= EH ; then
2
2
2
5.6.
H ;-Transform on the Space L;r
159
2
Theorem 5.57. Let a > 0; a1 > 0; a2 < 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H 2; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
(5.6.13)
aRe() = (r) + 2a2[ ; Re() ; 1] + Re(); Re( ) > ; Re() ; 1; Re( ) < 1 ; + Re():
(5.6.14) (5.6.15) (5.6.16)
If ; Re() 2= EH ; then
H 2; (L;r ) =
M;1=2;!=(2a2 )H 2a2;2a2 +!;1 La;1=2;+!=(2a2)
L ;1=2;Re(!)=(2a2);Re();r :
(5.6.17)
When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5.6.17).
Theorem 5.58. Let a > 0; a1 < 0; a2 > 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EH ; or if 1 < r 5 2; then the transform H 2; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(5.6.18)
aRe( ) = (r) ; 2a1 [ ; Re()] + + Re(); Re( ) > ; + Re(); Re( ) < ; Re():
(5.6.19) (5.6.20) (5.6.21)
If ; Re() 2= EH ; then
H 2; (L;r ) =
M+1=2+!=(2a1 )H ;2a1 ;2a1 +!;1 L;a ;1=2+;!=(2a1)
L +1=2+Re(!)=(2a1);Re();r :
(5.6.22)
When ; Re() 2 EH ; H 2; (L;r ) is a subset of the right-hand side of (5.6.22). to
The inversion formulas for the transform H 2; follow by noting that (5.1.5) is equaivalent
H 2M f = M; H 2;
from (5.1.10) and Lemma 3.1(iii), where the isometric property (5.4.1) and the relation (5.4.24) for the operator (M );1 inverse to M are used, and we have formally d x(+1)=h f (x) = hx1;;(+1)=h dx
Chapter 5. Modi ed H -Transforms on the Space L;r
160
1 q;m;p;n+1 H p+1;q+1 0
Z
"
x (;; h); (1 ; ai ; i ; i)n+1;p; (1 ; ai ; i ; i)1;n t (1 ; bj ; j ; j )m+1;q; (1 ; bj ; j ; j )1;m; (; ; 1; h)
t;;1
or d x;(+1)=h f (x) = ;hx1;;(+1)=h dx
1 q;m+1;p;n H p+1;q+1 0
Z
"
H 2; f
(t)dt
(5.6.23)
x (1 ; ai ; i; i)n+1;p ; (1 ; ai ; i ; i)1;n; (;; h) t (; ; 1; h); (1 ; bj ; j ; j )m+1;q; (1 ; bj ; j ; j )1;m
t;;1
H 2; f
#
#
(t)dt: (5.6.24) The validity of (5.6.23) and (5.6.24) can be proved by virtue of Theorems 5.23{5.24.
Theorem 5.59. Let a = 0; < 1 ; + Re() < and 0 < ; Re() < 0; and let
2 C ; h > 0. (a) If [1 ; + Re()] + Re() = 0 and f 2 L;2; then the inversion formula (5:6:23) holds for Re() > [ ; Re()]h ; 1 and (5:6:24) for Re() < [ ; Re()]h ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (5:6:23) holds for Re() > [ ; Re()]h ; 1 and (5:6:24) for Re() < [ ; Re()]h ; 1.
Theorem 5.60. Let a = 0; 1 < r < 1 and [1 ; + Re()] + Re() 5 1=2 ; (r); and
let 2 C ; h > 0. (a) If > 0; m > 0; < 1 ; + Re() < ; 0 < ; Re() < min[ 0; fRe( + 1=2)=g + 1] and if f 2 L;r ; then the inversion formulas (5:6:23) and (5:6:24) hold for Re() > [ ; Re()]h ; 1 and for Re() < [ ; Re()]h ; 1; respectively. (b) If < 0; n > 0; < 1 ; + Re() < ; max[ 0; fRe( + 1=2)=g + 1] < ; Re() < 0 and if f 2 L;r ; then the inversion formulas (5:6:23) and (5:6:24) hold for Re() > [ ; Re()]h ; 1 and for Re() < [ ; Re()]h ; 1; respectively.
Remark 5.4. The results in this section generalize those in Section 5.3 by putting
= = 0:
5.7. Bibliographical Remarks and Additional Information on Chapter 5
For Section 5.1. The integral transforms with H -function kernels (5.1.1){(5.1.5) are also investigated with a variable x in the upper or lower limit of the integral. These transformations, generalizing the Riemann{Liouville and Erdelyi{Kober fractional integrals (2.7.1), (3.3.1) and (2.7.2), (3.3.2), are de ned for x > 0 by # " Z x t (ai ; i)1:p ; ; ; 1
m;n t f (t)dt (5.7.1) H U;0+f (x) = x (x ; t ) H p;q kU x (bj ; j )1;q 0 and # " Z 1 (a ; ) x i i 1:p ;; ;1
m;n f (t)dt; (5.7.2) H U;;f (x) = x x (t ; x ) H p;q kU t (b ; ) t j j 1;q
5.7. Bibliographical Remarks and Additional Information on Chapter 5
161
respectively, where U(z) = (1 ; z ) z
(5.7.3)
and > 0, , , , and k are complex numbers. Such generalized operators were introduced by R.K. Saxena and Kumbhat [2] who investigated these transforms in the space Lr (R+ ) (r = 1), and proved their Mellin transforms for f(x) 2 Lr (R+ ) (1 5 r 5 2) and the relation of integration by parts Z1 0
g(x)
H U;0+f
(x)dx =
Z1 0
f(x)
H U;;g
(x)dx
(5.7.4)
f 2 Lr (R+ ); g 2 Lr0 (R+ ); r1 + r10 = 1 ; provided that a = 0, j arg(k)j < a =2 and some other conditions are satis ed. It should be noted that such results for the integral operators (5.7.1) and (5.7.2) with = = 0 were rst obtained by Kalla [4]. In [5] Kalla established the inversion formulas for such operators on the basis of their representations in the form of the Mellin convolution Z1 (5.7.5) (k f)(x) k xt f(t) dtt 0 with the kernel k involving the H-functions considered. Srivastava and Buschman [1] showed that the product of two operators of the form (5.7.1) and (5.7.2), studied by Kalla in [4] and [5], is the integral transform the kernel of which contains the H-function of two variables (see, for example, Srivastava, Gupta and Goyal [1]). One may nd the results above in Kalla [4], [5], [10, Section 4] and Srivastava and Buschman [1]. We also mention the paper by Galue, Kalla and Srivastava [1] where results similar to the above were established for the multiplier of Erdelyi{Kober type operators of the forms (3.3.1) and (3.3.2) involving the H-functions in their kernels. Dighe and Bhise [1] derived the composition of fractional integral operators with H-function kernels more general than those in (5.7.1) and (5.7.2), which led to an integral operator having a Fourier type kernel and generalizing the operator studied by Srivastava and Buschman [1]. Bhise and Dighe [1] also gave the conditions for the operator obtained to be bounded from Lr (R+ ) to Lq (R+ ). R.K. Saxena and Singh [1] studied the existence, the Mellin transform, composition properties and the inversion relations for more general integral transforms than (5.7.1) and (5.7.2) in which the m;n (z) is replaced by a more general construction. H-function Hp;q A method based on the Laplace transform was used by Srivastava and Buschman [2] and Srivastava [7] (see also Srivastava and Buschman [4]) to obtain the inversion formulas for the H -transforms
Hc0+f
(x) =
and
H
c; f
(x) =
Zx 0
Z1
x
(x ; t) H 1p;q;n
(t ; x) H m;n p;q
"
x ; t
(ai ; i)1:p (0; 1); (bj ; j )2;q
t ; x
(ai ; i)1:p ;; ;1 t f(t)dt; (bj ; j )1;q
"
#
#
t f(t)dt
(5.7.6)
(5.7.7)
respectively, which are the modi cations of the transforms (5.7.1) and (5.7.2) with = 1, = 1 and = ;1. For Sections 5.2 and 5.3. The results presented in these sections were proved by the authors in Kilbas and Saigo [7]. McBride and Spratt [2] (see also McBride [4], [5]) investigated the transform H 1 in (5.1.1) in the subspace Fr; of the space L;r de ned for 2 C and 1 5 r 5 1 by
dnf Fr; = ' 2 C 1 (R+ ) : xn n
dx 2 L;;r ; n 2 N0 :
(5.7.8)
Chapter 5. Modi ed H -Transforms on the Space L;r
162
This space, studied by McBride in [2], is a Frechet space with respect to the topology generated by the seminorms nr; 1 0 , where
n dn f r;
n (f) = x dxn
;;r
(f 2 Fr; ; n 2 N0 ):
(5.7.9)
McBride and Spratt de ned the transform H 1 by the relation (5.1.11) in the space Fr; with 1 < r < 1 and < < , where and are any real numbers such that H(s) = Hm;n p;q (s) given by (1.1.2) is analytic in the strip < Re(s) < . They proved the following results [2, Theorems 5.4 amd 5.6]: 1) If a = 0 and if 1 ; does not belong to the exceptional set EH of H(s) (see De nition 3.4), then 1 H is a continuous linear mapping from Fr; into Fr; , and if, in addition, 1 ; does not belong to the exceptional set 1=EH , that H 1 is a homeomorhism of Fr; onto Fr; whose inverse is the transform of the form (5.1.11) with H(s) replaced by 1=H(s). 2) If a > 0 and if 1 ; 2= EH , then H 1 is a continuous linear mapping from Fr; into the space Fr;;a , and if, in addition, 1 ; 2= E1=H , that H 1 is a homeomorhism of Fr; onto Fr;;a . Here the space Fr;;a is a certain subspace of Fr; which is de ned in terms of the simplest transform H 1 in (5.1.11) with H10;;01(s) = ;( + s=m) with 2 C and m > 0, which for 1 5 p < 1 and Re( ; =m) > 0 is given by
Nm f
(x) = m
Z1 0
tm exp (;tm ) f xt dtt (x > 0; 2 C ; m > 0)
(5.7.10)
for f 2 L;r . The substitution t = x show that this transform is the modi ed Laplace type transform of the form (7.1.10) with = m, k = m, = = 0 and f being replaced by Rf:
Nm f
(x) = m Lm;m;0;0 Rf (x);
(5.7.11)
where R is the elementary transform (3.3.13). Several authors have studied modi ed transforms H 1 and H 2 in (5.1.1) and (5.1.2) in the form (5.7.1) and (5.7.2). Kiryakova [3] and Kalla and Kiryakova [1] investigated the operators
I ;;m f (x) = x
2 i + i + 1 ; 1 ; 1 i i 1:m 0 6 t H m; m;m 6 4 1 x 0 j + 1 ; ; 1 j j 1;m
3
2 1 1 1 Z 1 H m;0 66 x i + i + i; i 1:m x x m;m 4 t j + 1 ; 1 j j 1;m
3
1Z x
K ;;m f (x) =
7 7 f(t)dt; 5
7 7 f(t)dt 5
(5.7.12)
(5.7.13)
in the space Lp (R+ ) (p = 1). They obtained the conditions for the boundedness of the operators I ;;m and K ;;m in Lp (R+ ), and proved some properties of them including the relations for their Mellin transforms, inversion formulas and the representations of the operators in (5.7.11) and (5.7.12) as compositions of m commuting Erdelyi{Kober type fractional integral operators (3.3.1) and (3.3.2), respectively. Kiryakova [4] established some of these properties for the operator (5.7.12) in some space of analytic functions. See also the book by Kiryakova [5] in this connection. Raina and Saigo [1] studied the generalized fractional integral operators I ;;m and K ;;m in the spaces Fr; and proved the conditions for their boundedeness, and some properties including their compositions with the di erential operator de ned by
df (x): f (x) = x dx
(5.7.14)
5.7. Bibliographical Remarks and Additional Information on Chapter 5
163
These investigations were continued by Saigo, Raina and Kilbas [1] who proved some properties of the operators (5.7.12) and (5.7.13), their Mellin transforms, the relation of fractional integration by parts Z 1
I ;;m g (x)f(x)dx =
0
Z 1
0
K ;;m f (x)g(x)dx
(5.7.15)
f 2 Fr; ; g 2 Fr0 ;; ; 1 5 r < 1; r1 + r10 = 1 ; the decomposition relations in terms of m commuting Erdelyi{Kober type fractional ;integral operators (3.3.1) and (3.3.2), extensions of the range of parameteres and the compositions of I ;m and K ;;m with the axisymmetric di erential operator of potential theory L de ned by d x2+1 d f(x) = d2f(x) + 2 + 1 df(x) : (5.7.16) L f (x) = x;2;1 dx dx dx2 x dx Using (5.7.15), Saigo, Raina and Kilbas [1] also de ned the operators I ;;m and K ;;m in the spaces F0r; of generalized functions (space of continuous linear functionals on Fr; equipped with the weak topology for which see McBride [2]), and proved in such a space F0r; the properties of the integral operators (5.7.12) and (5.7.13) similarly to those obtained in the space Fr; . Raina and Saigo [2] investigated in F0r; the compositions of such H -transforms with the fractional integration operators involving the Gauss hypergeometric function (2.9.2) in the kernel de ned by Saigo in [1] (see (7.12.45) and (7.12.46) in Section 7.12). More general than (5.7.12) and (5.7.13) the modi ed H -transforms
m;n Ip;q f
and
m;n Kp;q f
"
#
Zx t (ai ; i)1:p f(t)dt (x) = x1 H m;n p;q x (bj ; j )1;q 0
"
#
Z1 x (ai ; i)1:p f(t)dt 1 H m;n (x) = x p;q t (bj ; j )1;q x
(5.7.17)
(5.7.18)
in the spaces Fr; and F0r; were investigated by Kilbas and Saigo. The mapping properties were proved in Kilbas and Saigo [2], [3], while the compositions of these transforms with the di erential operator of axisymmetric theory L in (5.7.16) were given in Saigo and Kilbas [2], [3]. For Sections 5.4{5.6. As was indicated in Section 4.11 (For Sections 4.9 and 4.10), the papers by R. Singh [1], K.C. Gupta and P.K. Mittal [1], [2] and Nasim [2] are devoted to the inversion of the tramsforms H 1;0 and H 0; given by (5.1.3). Mittal [1] showed that the composition of the H transform considered by K.C. Gupta and P.K. Mittal [1], with the Varma transform (see Section 7.2) also gives the H -transform with another H-function in the kernel. Using the Mellin transform, Mehra [2] proved the inversion formula for the generalized H 1-transform (5.1.5) of the form
H
1f
(x) =
Z1 0
+1 H m;n p+1;q
"
x a
t
#
(0; ); (ai; i)1;p f(t) dtt (x > 0) (bj ; j )1;q
(5.7.19)
with real a and . de Amin and Kalla [1] derived the relation betweeen the Hardy transform (8.12.6) and the H -transform of the form (4.11.17) considered by K.C. Gupta and P.K. Mittal [1], and pointed out that in special cases their result reduces to the relations between the Hardy transform and the Mejer, Varma, Hankel and Laplace transforms (see Chapter 7). Treating the H-function transform of the form H 0;1 given by (5.1.3), Srivastava and Buschman [3] established an expression for the H-function transform of the Mellin convolution (5.7.4) of two functions in terms of the Mellin convolution of H-function transforms of a function.
Chapter 5. Modi ed H -Transforms on the Space L;r
164
Dange and Chaudhary [1] proved the Abelian theorems for the modi ed H 2-transform of the form Z1 1 2 H 0;0f (x) = x 0 H 12;;22
"
x t
#
(a1 ; 1); (1 ; a2 ; 2; 2) f(t)dt (x > 0) (b1 ; 1); (b2 ; 2)
(5.7.20)
with real and showed that such Abelian theorems also hold for the special space of distributions f discussed by Zemanian [6]. Malgonde [1] extended the modi ed H -transform (5.1.4) of the form (H
1 f)(x) = 0;
Z 1 ; t 0
m;n+1 ;() H p+1;q
" x t
#
(1 ; ; 1); (ai; i)1:p f(t)dt (x > 0) (bj ; j )1;q
(5.7.21)
with > 0 to a class of Banach space valued distributions, following the procedure by Zemanian [6], and derived a complex inversion formula for such a transform. Virchenko and Haidey [1] considered the modi ed H -transform 3 2 7 f(2pt)dt 1 6 x H 02;m; 5 04t 0 1 ; 2 ; 1 m times ; + 1 ; 2 ; m times
Z1
(x > 0)
(5.7.22)
and proved its existence and the inversion relation in the space M;c; 1 (see Samko, Kilbas and Marichev [1, Section 36]). The results in Sections 5.4{5.6 have not been published before.
Chapter 6 G-TRANSFORM AND MODIFIED G-TRANSFORMS ON THE SPACE L;r 6.1. G-Transform on the Space L;r This section deals with the G-transforms, namely, the integral transforms of the form of (3.1.2):
Gf (x) =
1 m;n G 0 p;q
Z
"
(ai )1;p # xt f (t)dt (bj )1;q
(6.1.1)
(ai )1;p # with the Meijer G-function z de ned in (2.9.1) as kernel. A formal Mellin (bj )1;q transform M, de ned in (2.5.1), of (6.1.1) gives a similar relation to (3.1.5)
Gm;n p;q
"
MGf (s) = Gm;n p;q
(ai)1;p # Mf (1 ; s); s (bj )1;q
"
(6.1.2)
where Gm;n p;q
"
(ai )1;p # m;n " (a)p # m;n " a1 ; ; ap # s = Gp;q s = Gp;q s (bj )1;q (b)q b1; ; bq
m
Y
=
j =1 p Y i=n+1
;(bj + s)
;(ai + s)
n
Y
;(1 ; ai ; s)
i=1 q Y
j =m+1
;(1 ; bj ; s)
:
(6.1.3)
In this section on the basis of the results in Chapters 3 and 4 we charactrerize the mapping properties such as the existence, boundedness and representative properties of the G-transform (6.1.1) on the spaces L;r and also give inversion formulas for this transform. As indicated in Section 3.1, (6.1.1) is a particular case of the H -transform in (3.1.1) when
1 = = p = 1 = = q = 1:
(6.1.4)
The numbers a ; ; a1; a2; and given in (1.1.7), (1.1.8), (1.1.11), (1.1.12), (3.4.1) and (3.4.2) for the H -function (1.1.1), are simpli ed for the Meijer G-function (6.1.2) and take 165
166
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
the forms:
a = 2(m + n) ; p ; q; = q ; p; a1 = m + n ; p; a2 = m + n ; q ; 8 < ; min [Re(bj )] if m > 0; = : 15j5m ;1 if m = 0;
(6.1.5) (6.1.6) (6.1.7) (6.1.8) (6.1.9)
and 8 <
=:
1 ; max [Re(ai )] if n > 0; 15i5n 1 if n = 0;
(6.1.10)
while in (1.1.10) remains the same:
=
q
X
j =1
bj ;
p
X
i=1
ai + p ;2 q :
(6.1.11)
De nition 3.4 on the exceptional set takes the following form. "
#
(a ) De nition 6.1. Let the function G(s) = z i 1;p be given in (6.1.3) and let (bj )1;q the real numbers and be de ned in (6.1.9) and (6.1.10), respectively. We call the exceptional set of G the set EG of real numbers such that < 1 ; < and G(s) has a zero on the line Re(s) = 1 ; .
Gm;n p;q
From Theorems 3.6 and 3.7 we obtain the L;2 -theory of the G-transform (6.1.1).
Theorem 6.1. We suppose that (a) < 1 ; < and either of the conditions (b) (c) a = 0; (1 ; ) + Re() 5 0 holds. Then we have the results: (i) There is a one-to-one transform G2 [L;2; L1;;2] such that (6:1:2) holds for Re(s) =
a > 0; or
1 ; and f 2 L;2 . If a = 0; (1 ; ) + Re() = 0 and 2= EG ; then the transform G maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then the relation 1
Z
0
f (x) Gg (x)dx =
1
Z
0
Gf (x)g(x)dx
(6.1.12)
holds.
(iii) Let f 2 L;2 and 2 C . If Re() > ;; then Gf is given by
" # Z 1 ;; a ; ; a 1 p d m;n +1 Gf (x) = x; dx x+1 0 Gp+1;q+1 xt b ; ; b ; ; ; 1 f (t)dt: 1 q
(6.1.13)
6.1.
G-Transform on the Space L;r
167
When Re() < ;;
Gf
(x) = ;x;
" # d x+1 Z 1 Gm+1;n xt a1; ; ap; ; f (t)dt: dx 0 p+1;q+1 ; ; 1; b1; ; bq
(6.1.14)
(iv) The transform G is independent of in the sense that; if and satisfy (a), and e
either (b) or (c), and if the transforms G and G are de ned in L;2 and Le ;2; respectively; by (6:1:2); then Gf = Ge f for f 2 L;2 \ Le ;2. (v) If a > 0 or if a = 0; (1 ; ) + Re() < 0; then Gf is given in (6:1:1) for f 2 L;2: e
Corollary 6.1.1. Let < and let one of the following conditions hold: (b) a > 0; (e) a = 0; > 0 and < ; Re() ;
(f) a = 0; < 0 and > ; Re() ; (g) a = 0; = 0 and Re() 5 0:
Then the G-transform can be de ned on L;2 with < < .
Theorem 6.2. Let < 1 ; < and either of the following conditions hold: (b) a > 0; (d) a = 0; (1 ; ) + Re() < 0: Then for f 2 L;2 and x > 0;
Gf (x) is given in (6:1:1).
Corollary 6.2.1. Let < and let one of the following conditions hold: (b) a > 0; (h) a = 0; > 0 and < ; Re() + 1 ; (i) a = 0; < 0 and > ; Re() + 1 ; (j) a = 0; = 0 and Re() < 0:
Then the G-transform can be de ned by (6:1:1) on L;2 with < < . Using the results in Sections 4.1{4.4, we present the L;r -theory of the G-transform (6.1.1) when a = 0. From Theorems 4.1{4.4 we obtain the mapping properties and the range of G on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0. Here a ; ; a1; a2; ; and are taken as in (6.1.5), (6.1.6), (6.1.7), (6.1.8), (6.1.9), (6.1.10) and (6.1.11), respectively.
168
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
Theorem 6.3. Let a = = 0; Re() = 0 and < 1 ; < : Let 1 < r < 1. (a) The transform G de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;r ]. (b) If 1 < r 5 2; then the transform G is one-to-one on L;r and there holds the equality
(6:1:2) for f 2 L;r and Re(s) = 1 ; . (c) If f 2 L;r and g 2 L;r0 with r0 = r=(r ; 1); then the relation (6:1:12) holds. (d) If 2= EG ; then the transform G is one-to-one on L;r and there holds
G(L;r ) = L1;;r : (6.1.15) (e) If f 2 L;r and 2 C ; then Gf is given in (6:1:13) for Re() > ;; while in (6:1:14)
for Re() < ;:
Theorem 6.4. Let a = = 0; Re() < 0 and < 1 ; < ; and let either m > 0 or
n > 0. Let 1 < r < 1. (a) The transform G de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform G is one-to-one on L;r and there holds the equality (6:1:2) for f 2 L;r and Re(s) = 1 ; . (c) If f 2 L;r and g 2 L;s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (6:1:12) holds. (d) Let k > 0. If 2= EG ; then the transform G is one-to-one on L;r and there hold
G (L;r ) = I;;;k;; =k (L1;;r )
(6.1.16)
; G (L;r ) = I0+; k; =k;1 (L1;;r )
(6.1.17)
for m > 0; and for n > 0. If 2 EG ; G (L;r ) is a subset of the right-hand sides of (6:1:16) and (6:1:17) in the respective cases. (e) If f 2 L;r and 2 C ; then Gf is given in (6:1:13) for Re() > ;; while in (6:1:14) for Re() < ; . Furthermore Gf is given in (6.1.1).
Theorem 6.5. Let a = 0; 6= 0; < 1; < ; 1 < r < 1 and (1; )+Re() 5 1=2;
(r); where (r) is de ned in (3:3:9): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform G de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; (1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform G is one-to-one on L;r and there holds the equality (6:1:2) for f 2 L;r and Re(s) = 1 ; . (c) If f 2 L;r and g 2 L;s with 1 < s < 1; 1=r +1=s = 1 and (1 ; )+Re() 5 1=2 ; max[ (r); (s)]; then the relation (6:1:12) holds. (d) If 2= EG ; then the transform G is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there holds
G(L;r ) = M=+1=2H ;
L ;1=2;Re()=;r :
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6:1:18):
(6.1.18)
6.1.
G-Transform on the Space L;r
169
(e) If f 2 L;r ; 2 C and (1 ; ) + Re() 5 1=2 ; (r); then Gf is given in (6:1:13)
for Re() > ;; while in (6:1:14) for Re() < ; . If (1 ; ) + Re() < 0; Gf is given in (6.1.1).
Corollary 6.5.1. Let 1 < r < 1; < ; a = 0 and let one of the following conditions
hold:
(a) > 0; < 1 21 ; Re() ; (r) ;
(b) < 0; > 1 21 ; Re() ; (r) ; (c) = 0; Re() 5 0:
Then the transform G can be de ned on L;r with < 1 ; < . From Theorem 4.5 in Section 4.5 we obtain the L;r -theory of the G-transform (6.1.1) with a > 0 in L;r -spaces for any 2 C and 1 5 r 5 1:
Theorem 6.6. Let a > 0; < 1 ; < and 1 5 r 5 s 5 1: (a) The G-transform de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ].
When 1 5 r 5 2; G is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s0 with 1=s + 1=s0 = 1; then the relation (6:1:12) holds.
According to Theorems 4.6{4.10 we characterize the boundedness and the range of G on
L;r for a > 0 but with various combinations of the signs of a1 and a2 which are classi ed in ve cases: a1 > 0; a2 > 0; a1 > 0; a2 = 0; a1 = 0; a2 > 0; a > 0; a1 > 0; a2 < 0; and a > 0; a1 < 0; a2 > 0:
Theorem 6.7. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; < and ! = + a1 ; a2 +1
and let 1 < r < 1: (a) If 2= EG ; or if 1 5 r 5 2; then the transform G is one-to-one on L;r . (b) If Re(!) = 0 and 2= EG ; then G(L;r ) = La1 ; La2;1; ;!=a2 (L1;;r ): When 2 EG ; G(L;r ) is a subset of the right-hand side of (6:1:19): (c) If Re(!) < 0 and 2= EG ; then G(L;r ) = I;;;1!=a1;;a1 La1 ; La2 ;1; (L1;;r ): When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.20).
(6.1.19)
(6.1.20)
Theorem 6.8. Let a1 > 0; a2 = 0; m > 0; < 1 ; < and ! = + a1 + 1=2 and let
1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) If Re(!) = 0 and 2= EG ; then G(L;r ) = La1 ; ;!=a1 (L;r ):
(6.1.21)
170
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6:1:21): (c) If Re(!) < 0 and 2= EG ; then
G(L;r ) = I;;;1!=a;;a La; (L;r ):
1
1
(6.1.22)
1
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.22).
Theorem 6.9. Let a1 = 0; a2 > 0; n > 0; < 1 ; < and ! = ; a2 + 1=2 and let
1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) If Re(!) = 0 and 2= EG ; then
G(L;r ) = L;a; +!=a (L;r ): 2
(6.1.23)
2
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6:1:23): (c) If Re(!) < 0 and 2= EG ; then ;! L;a ; (L;r ): G(L;r ) = I0+;1 =a ;a ;1
2
(6.1.24)
2
2
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.24).
Theorem 6.10. Let a > 0; a1 > 0; a2 < 0; < 1 ; < and let 1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
(6.1.25)
aRe() = (r) + 2a2 ( ; 1) + Re(); Re( ) > ; 1; Re( ) < 1 ; :
(6.1.26) (6.1.27) (6.1.28)
If 2= EG ; then
G(L;r ) = M1=2+!=(2a)H ;2a;2a+!;1L;a;1=2+;!=(2a)
2
2
2
2
L3=2; +Re(!)=(2a2 );r :
(6.1.29)
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.29).
Corollary 6.10.1. Let a > 0; a1 > 0; a2 < 0; < 1 ; < and let 1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) Let ! = a ; ; 1=2 and let and be chosen such that any of the following
conditions holds: (i) a Re( ) = (r) ; 2a2 + Re(); Re( ) = ; ; Re( ) 5 if m > 0; n > 0;
(ii) a Re( ) 5 (r) ; 2a2 + Re(); Re( ) > ; 1; Re( ) < 1 ; if m = 0; n > 0;
6.1.
G-Transform on the Space L;r
171
(iii) aRe( ) = (r) + 2a2( ; 1) + Re(); Re( ) = ; ; Re( ) 5 if m > 0; n = 0:
Then; if 2= EG ; G(L;r ) can be represented by the relation (6:1:29): When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.29).
Corollary 6.10.2. Let a > 0; a1 > 0; a2 < 0; m > 0; n > 0; < 1 ; < and
1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) Let a ; 2a2 +Re()+ (r) 5 0; ! = ;a ; ; 1=2 and let be chosen such that Re( ) 5 . Then if 2= EG ; G(L;r ) can be represented in the form (6:1:29). When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.29).
Theorem 6.11. Let a > 0; a1 < 0; a2 > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(6.1.30)
aRe() = (r) ; 2a1 + + Re(); Re( ) > ; ; Re( ) < :
(6.1.31) (6.1.32) (6.1.33)
If 2= EG ; then
G(L;r ) = M;1=2;!=(2a)H 2a;2a+!;1La;1=2;+!=(2a)
1
1
1
1
L1=2; ;Re(!)=(2a1 );r :
(6.1.34)
When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.34).
Corollary 6.11.1. Let a > 0; a1 < 0; a2 > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r . (b) Let ! = a ; ; ; 1=2; and let and be chosen such that either of the following
conditions holds:
(i) a Re( ) = (r) ; 2a1(1 ; )++Re(); Re( ) = ; 1; Re( ) 5 1 ; if m > 0; n > 0; (ii) a Re( ) = (r) ; 2a1 + + Re(); Re( ) = ; 1; Re( ) 5 1 ; if m = 0; n > 0; (iii) aRe( ) = (r) ; 2a1(1 ; ) + + Re(); Re( ) > ;; Re( ) < if m > 0; n = 0:
Then; if 2= EG ; G(L;r ) can be represented by the relation (6:1:34): When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.34).
Corollary 6.11.2. Let a > 0; a1 < 0; a2 > 0; m > 0; n > 0; < 1 ; < ; and let
1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G is one-to-one on L;r .
172
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
(b) Let 2a1 ; a2 + Re() + (r) 5 0; and let be chosen such that Re( ) 5 1 ; .
Then; if 2= EG ; G(L;r ) can be represented by the relation (6:1:34): When 2 EG ; G(L;r ) is a subset of the right-hand side of (6.1.34). It follows from the results in Sections 4.9 and 4.10 that the inversion formulas for the G-transform (6.1.1) have the respective forms: d x+1 f (x) = x; dx " # Z 1 ;; ;a n+1 ; ; ;ap ; ;a1; ; ;an q ; m;p ; n +1 G p+1;q+1 xt (Gf )(t)dt; (6.1.35) 0 ;bm+1 ; ; ;bq; ;b1; ; ;bm; ; ; 1 d x+1 f (x) = ;x; dx " # Z 1 ;a n+1 ; ; ;ap; ;a1 ; ; ;an ; ; q ; m +1 ;p ; n G p+1;q+1 xt (Gf )(t)dt (6.1.36) 0 ; ; 1; ;bm+1; ; ;bq; ;b1; ; ;bm corresponding to (6.1.13) and (6.1.14), provided that a = 0: The conditions for the validity of (6.1.35) and (6.1.36) follow from Theorems 4.11{4.14, if we take into account that the numbers 0 and 0 in (4.9.6) and (4.9.7) take the forms: 8 > > <
0 = > > :
max [Re(bj )] if q > m;
m+15j 5q
;1
if q = m
(6.1.37)
and 8 > > <
0 = > > :
min [Re(ai )] + 1 if p > n;
n+15i5p
1
if p = n:
(6.1.38)
We note that if 0 < < 0; is not in the exceptional set of G (see De nition 6.1). From Theorems 4.11 and 4.12 we obtain the conditions for the inversion formulas (6.1.35) and (6.1.36) in the space L;2 .
Theorem 6.12. Let a = 0; < 1 ; < and 0 < < 0; and let 2 C . (a) If (1 ; ) + Re() = 0 and if f 2 L;2; then the inversion formula (6:1:35) holds for
Re() > ; 1 and (6:1:36) for Re() < ; 1. (b) If = Re() = 0 and if f 2 L;r (1 < r < 1); then the inversion formula (6:1:35) holds for Re() > ; 1 and (6:1:36) for Re() < ; 1. Theorems 4.13 and 4.14 give the conditions for the inversion formulas (6.1.35) and (6.1.36) in L;r -space when 6= 0.
Theorem 6.13. Let a = 0; 1 < r < 1 and (1 ; ) + Re() 5 1=2 ; (r); and let
2 C.
6.2. Modi ed G-Transforms
173
(a) If > 0; m > 0; < 1 ; < ; 0 < < min[ 0; fRe( + 1=2)=g + 1] and f 2 L;r ;
then the inversion formulas (6:1:35) and (6:1:36) hold for Re() > ; 1 and for Re() < ; 1; respectively. (b) If < 0; n > 0; < 1 ; < ; max[ 0; fRe( + 1=2)=g + 1] < < 0 and if f 2 L;r ; then the inversion formulas (6:1:35) and (6:1:36) hold for Re() > ; 1 and for Re() < ; 1; respectively.
6.2. Modi ed G-Transforms Let us consider the following modi cations of the G-transform (6.1.1): # (a ) i 1;p x 1 m;n G f (x) = 0 Gp;q t (b ) f (t) dtt ; j 1;q # " Z 1 (a ) i 1;p t 2 m;n G f (x) = 0 Gp;q x (b ) f (t) dtx ; j 1;q " # Z 1 (a ) i 1;p m;n G;f (x) = x 0 Gp;q xt t f (t)dt; (bj )1;q # " Z 1 (a ) i 1 ;p x t f (t) dtt G1; f (x) = x 0 Gm;n p;q t (bj )1;q
Z
"
1
(6.2.1) (6.2.2) (6.2.3) (6.2.4)
and
G;f
2
(x) = x
Z
1
0
Gm;n p;q
"
# t (ai )1;p t f (t) dt ; x (bj )1;q x
(6.2.5)
where ; 2 C . These transforms are connected with the G-transform (6.1.1) by the relations
G1f (x) = GRf (x); G2f (x) = RGf (x); G;f (x) = M GMf (x); G1; f (x) = M GRMf (x) = M G1Mf (x)
(6.2.6)
(6.2.7)
(6.2.8) (6.2.9)
and
G2; f (x) = M RGM f (x) = M G2Mf (x);
(6.2.10)
respectively, where R and M are the operators given in (3.3.13) and (3.3.11). Due to (6.2.6){ (6.2.10), (6.1.2) and Lemma 3.1 the Mellin transforms of the modi ed G-transforms (6.2.1){
174
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
(6.2.5) for \suciently good" function f are given by the relations MG f
1
MG f
(s) = Gm;n p;q
(s) = Gm;n p;q
2
"
(ai )1;p # Mf (s); s (bj )1;q # (ai )1;p M f (s); 1;s (bj )1;q
"
# ( a ) i 1 ;p M f (1 ; s ; + ); MG; f (s) = Gm;n s+ p;q (bj )1;q " # (ai )1;p 1 m;n MG; f (s) = Gp;q M f (s + + ) s + (bj )1;q
(6.2.12)
"
(6.2.11)
(6.2.13) (6.2.14)
and MG; f
2
(s) = Gm;n p;q
"
# (ai )1;p M f (s + + ) 1;s ; (bj )1;q
(6.2.15)
#
"
(ai )1;p in terms of the s de ned in (6.1.3). (bj )1;q It is directly veri ed that for the \suciently good" functions f and g the following formulas hold function Gm;n p;q Z
f (x) G g (x)dx =
Z
f (x) G g (x)dx =
Z
f (x) G; g (x)dx =
Z
f (x) G1; g (x)dx =
Z
1 0
Z
1 0
Z
1
0 Z 1 0
1 2
1
1
G2f (x)g(x)dx;
0
G1f (x)g(x)dx;
(6.2.17)
G; f (x)g(x)dx;
(6.2.18)
0 1 0
1
G2; f (x)g(x)dx
0
(6.2.16)
(6.2.19)
and Z
1 0
f (x) G; g (x)dx =
2
Z
1 0
G1; f (x)g(x)dx:
(6.2.20)
The modi ed G-transforms (6.2.1){(6.2.5) are particular cases of the modi ed H -transforms (5.1.1){(5.1.5) when the condition (6.1.4) is satis ed. Therefore the properties in L;r -space for the modi ed G-transforms follow from the corresponding results for the modi ed H -transforms proved in Chapter 5. We suppose in Sections 6.2{6.6 below that a ; ; a1; a2; ; and are given in (6.1.5), (6.1.6), (6.1.7), (6.1.8), (6.1.9), (6.1.10) and (6.1.11), respectively
6.3.
G1-Transform on the Space L;r
175
6.3. G1-Transform on the Space L;r We rst investigate the transform G1 de ned in (6.2.1). Let EG be the exceptional set of the function Gm;n p;q (s) given in De nition 6.1. From the results in Section 5.2 we obtain the L;2 and L;r -theory of the modi ed G1 -tranform (6.2.1). The rst result follows from Theorem 5.1.
Theorem 6.14. We suppose that (a) < < and that either of the conditions (b) a > 0; or (c) a = 0; + Re() 5 0 holds. Then we have the following results: (i) There is a one-to-one transform G1 2 [L;2; L;2] such that (6:2:11) holds for Re(s) = and f 2 L;2 . If a = 0; + Re() = 0 and 1 ; 2= EG ; then the transform G1 maps L;2 onto L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation (6:2:16) holds for G1. (iii) Let f 2 L;2 and 2 C . If Re() > ; 1; then G1f is given by " Z 1 ;; a ; ; a x d m;n +1 +1 1 ; G f (x) = x dx x 0 Gp+1;q+1 t b ; 1; b ; ;p; 1 1 q
#
f (t) dt: t
(6.3.1)
When Re() < ; 1; Z 1 a ; ; a ; ; G1f (x) = ;x; dxd x+1 0 Gmp+1+1;q;n+1 xt ;1 ; 1; bp ; ; b 1 q
"
#
f (t) dt: t
(6.3.2)
(iv) The transform G1 is independent of in the sense that, if and satisfy (a), and e
(b) or (c), and if the transforms G1 and g G1 are de ned in L;2 and Le;2; respectively; by (6:2:11); then G1 f = g G1f for f 2 L;2 \ Le;2. (v) If a > 0 or if a = 0; + Re() < 0; then for f 2 L;2; G1f is given in (6.2.1). When a = 0; from Theorems 5.2{5.4 we obtain the mapping properties and the range of G1 on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0.
Theorem 6.15. Let a = = 0; Re() = 0; < < and let 1 < r < 1. (a) The transform G1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;r ]. (b) If 1 < r 5 2; then the transform G1 is one-to-one on L;r and there holds the equality
(6:2:11) for f 2 L;r and Re(s) = . (c) If f 2 L;r and g 2 L1;;r0 with r0 = r=(r ; 1); then the relation (6:2:16) holds. (d) If 1 ; 2= EG ; then the transform G1 is one-to-one on L;r and there holds
G1(L;r ) = L;r : (6.3.3) (e) If f 2 L;r and 2 C ; then G1f is given in (6:3:1) for Re() > ; 1; while in (6:3:2)
for Re() < ; 1:
Theorem 6.16. Let a = = 0; Re() < 0 and < < ; and let either m > 0 or
n > 0. Let 1 < r < 1. (a) The transform G1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s = r such that 1=s > 1=r + Re().
176
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
(b) If 1 < r 5 2; then the transform G1 is one-to-one on L;r and there holds the equality
(6:2:11) for f 2 L;2 and Re(s) = . (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (6:2:16) holds. (d) Let k > 0. If 1 ; 2= EG ; then the transform G1 is one-to-one on L;r and there hold
G1 (L;r ) = I;;;k;; =k (L;r )
(6.3.4)
for m > 0; and ; G1 (L;r ) = I0+; (6.3.5) k; =k;1 (L;r ) for n > 0. When 1 ; 2 EG ; G1 (L;r ) is a subset of the right-hand sides of (6:3:4) and (6:3:5)
in the respective cases. (e) If f 2 L;r and 2 C ; then G1f is given in (6:3:1) for Re() > ; 1; while in (6:3:2) for Re() < ; 1. Furthermore G1 f is given in (6.2.1).
Theorem 6.17. Let a = 0; 6= 0; < < ; 1 < r < 1 and + Re() 5 1=2 ; (r):
Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform G1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform G1 is one-to-one on L;r and there holds the equality (6:2:11) for f 2 L;2 and Re(s) = . (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1; 1=r + 1=s = 1 and + Re() 5 1=2 ; max[ (r); (s)]; then the relation (6:2:16) holds. (d) If 1 ; 2= EG ; then the transform G1 is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there holds
G1(L;r ) = M=+1=2H ;
L1=2; ;Re()=;r :
(6.3.6)
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6:3:6): (e) If f 2 L;r ; 2 C and + Re() 5 1=2 ; (r); then G1f is given in (6:3:1) for Re() > ; 1; while in (6:3:2) for Re() < ; 1. If + Re() < 0; G1 f is given in (6.2.1). From Theorem 5.5 we obtain the L;r -theory of the transform G1 in (6.2.1) for a > 0.
Theorem 6.18. Let a > 0; < < and 1 5 r 5 s 5 1: (a) The transform G1 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s].
If 1 5 r 5 2; then G1 is a one-to-one transform from L;r onto L;s . (b) If f 2 L;r and g 2 L1;;s0 with 1=s + 1=s0 = 1; then the relation (6:2:16) holds.
When a > 0; the boundedness and the range of G1 on L;r can be obtained in ve cases as in Theorems 5.6{5.10.
Theorem 6.19. Let a1 > 0; a2 > 0; m > 0; n > 0; < < and ! = + a1 ; a2 + 1
and let 1 < r < 1:
6.3.
G1-Transform on the Space L;r
177
(a) If 1 ; 2= EG ; or if 1 5 r 5 2; then the transform G1 is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; 2= EG ; then
G1(L;r ) =
La1 ; La2 ;1; ;!=a2
(L;r ):
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6:3:7): (c) If Re(!) < 0 and 1 ; 2= EG ; then G1(L;r ) = I;;;1!=a1 ;;a1 La1; La2 ;1; (L;r ):
(6.3.7)
(6.3.8)
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6.3.8).
Theorem 6.20. Let a1 > 0; a2 = 0; m > 0; < < and ! = + a1 + 1=2 and let
1 < r < 1: (a) If 1 ; 2= EG ; or if 1 < r 5 2; then the transform G1 is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; 2= EG ; then G1(L;r ) = La1 ; ;!=a1 (L1;;r ): (6.3.9) When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6:3:9): (c) If Re(!) < 0 and 1 ; 2= EG ; then G1(L;r ) = I;;;1!=a1;;a1 La1 ; (L1;;r ): (6.3.10)
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6.3.10).
Theorem 6.21. Let a1 = 0; a2 > 0; n > 0; < < and ! = ; a2 + 1=2 and let
1 < r < 1: (a) If 1 ; 2= EG ; or if 1 < r 5 2; then the transform G1 is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; 2= EG ; then G1(L;r ) = L;a2 ; +!=a2 (L1;;r ): (6.3.11) When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6:3:11): (c) If Re(!) < 0 and 1 ; 2= EG ; then ;! L;a ; (L1;;r ): (6.3.12) G1(L;r ) = I0+;1 =a2 ;a2 ;1 2
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6.3.12).
Theorem 6.22. Let a > 0; a1 > 0; a2 < 0; < < and let 1 < r < 1: (a) If 1 ; 2= EG ; or if 1 < r 5 2; then the transform G1 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
aRe() = (r) ; 2a2 + Re(); Re( ) > ; ; Re( ) < :
(6.3.13) (6.3.14) (6.3.15) (6.3.16)
178
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
If 1 ; 2= EG ; then
G1(L;r ) = M1=2+!=(2a)H ;2a;2a+!;1L;a ;1=2+;!=(2a)
2
2
2
2
L +1=2+Re(!)=(2a2 );r :
(6.3.17)
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6.3.17).
Theorem 6.23. Let a > 0; a1 < 0; a2 > 0; < < and let 1 < r < 1: (a) If 1 ; 2= EG ; or if 1 < r 5 2; then the transform G1 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(6.3.18)
aRe() = (r) + 2a1( ; 1) + + Re(); Re( ) > ; 1; Re( ) < 1 ; :
(6.3.19) (6.3.20) (6.3.21)
If 1 ; 2= EG ; then
G1(L;r ) = M;1=2;!=(2a)H 2a;2a+!;1La;1=2;+!=(2a)
1
1
1
1
L ;1=2;Re(!)=(2a1 );r :
(6.3.22)
When 1 ; 2 EG ; G1(L;r ) is a subset of the right-hand side of (6.3.22). The inversion formulas for the transform G1 in (6.2.1) follow from those for (5.2.27) and (5.2.28). They take the forms d x;(+1) f (x) = ;x+1 dx # " Z 1 ;; ;a n+1 ; ; ;ap ; ;a1; ; ;an t q ; m;p ; n +1 (G1 f )(t)dt (6.3.23) G p+1;q+1 x 0 ;bm+1 ; ; ;bq; ;b1; ; ;bm; ; ; 1 and
d x;(+1) f (x) = x+1 dx
Z
1 q;m+1;p;n G p+1;q+1 0
"
# t ;an+1 ; ; ;ap; ;a1 ; ; ;an ; ; 1 x ; ; 1; ;bm+1; ; ;bq; ;b1; ; ;bm (G f )(t)dt; (6.3.24)
respectively. The conditions for the validity of (6.3.23) and (6.3.24) follow from Theorems 5.11 and 5.12, if we take into account that the numbers 0 and 0 are given in (6.1.37) and (6.1.38).
Theorem 6.24. Let a = 0; < < and 0 < 1 ; < 0; and let 2 C .
6.4.
G2-Transform on the Space L;r
(a) If + Re() = 0 and f 2
179 L;2 ; then the inversion formula (6:3:23) holds for
Re() > ; and (6:3:24) for Re() < ; . (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (6:3:23) holds for Re() > ; and (6:3:24) for Re() < ; .
Theorem 6.25. Let a = 0; 1 < r < 1 and + Re() 5 1=2 ; (r); and let 2 C . (a) If > 0; m > 0; < < ; 0 < 1 ; < min[ 0; fRe( + 1=2)=g + 1] and
if f 2 L;r ; then the inversion formulas (6:3:23) and (6:3:24) hold for Re() > and for Re() < ;; respectively. (b) If < 0; n > 0; < < ; max[ 0; fRe( + 1=2)=g + 1] < 1 ; < 0 and if f 2 L;r ; then the inversion formulas (6:3:23) and (6:3:24) hold for Re() > and for Re() < ;; respectively.
6.4. G2-Transform on the Space L;r
Now we treat the transform G2 de ned in (6.2.2). From the results in Section 5.3 we obtain L;2 - and L;r -theory for this transform. The rst result comes from Theorem 5.13.
Theorem 6.26. We suppose that (a) < 1 ; < and that either of the conditions (b) a > 0; or (c) a = 0; (1 ; ) + Re() 5 0 holds. Then we have the following results: (i) There is a one-to-one transform G2 2 [L;2; L;2] such that (6:2:12) holds for Re(s) =
and f 2 L;2 . If a = 0; (1 ; ) + Re() = 0 and 2= EG ; then the transform G2 maps L;2 onto L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation (6:2:17) holds. (iii) Let f 2 L;2 and 2 C . If Re() > ;; then G2f is given by " # Z 1 ;; a ; ; a 1 p t d m;n +1 ; ; 1 2 +1 G f (t)dt: G f (x) = ;x dx x 0 p+1;q+1 x b1; ; bq ; ; ; 1
(6.4.1)
When Re() < ;; Z 1 a ; ; a ; ; 1 p d ; ; 1 2 +1 Gmp+1+1;q;n+1 xt G f (x) = x dx x 0 ; ; 1; b1; ; bq
"
#
f (t)dt:
(6.4.2)
(iv) The transform G2 is independent of in the sense that, if and satisfy (a), and e
(b) or (c), and if the transforms G2 and g G2 are de ned in L;2 and Le;2; respectively; by (6:2:12); then G2 f = g G2f for f 2 L;2 \ Le;2. (v) If a > 0 or if a = 0; (1 ; )+Re() < 0; then for f 2 L;2; G1f is given in (6.2.2). When a = 0; from Theorems 5.14{5.16 we obtain the mapping properties and the range of G2 on L;r in three di erent cases when either = Re() = 0 or = 0; Re() < 0 or 6= 0.
Theorem 6.27. Let a = = 0; Re() = 0 and < 1 ; < ; and let 1 < r < 1. (a) The transform G2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;r ].
180
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
(b) If 1 < r 5 2; then the transform G2 is one-to-one on L;r and there holds the equality
(6:2:12) for f 2 L;2 and Re(s) = : (c) If f 2 L;r and g 2 L1;;r0 with r0 = r=(r ; 1); then the relation (6:2:17) holds. (d) If 2= EG ; then the transform G2 is one-to-one on L;r and there holds
G2(L;r ) = L;r : (6.4.3) (e) If f 2 L;r and 2 C ; then G2f is given in (6:4:1) for Re() > ;; while in (6:4:2)
for Re() < ;:
Theorem 6.28. Let a = = 0; Re() < 0 and < 1 ; < ; and let either m > 0 or
n > 0. Let 1 < r < 1. (a) The transform G2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform G2 is one-to-one on L;r and there holds the equality (6:2:12) for f 2 L;2 and Re(s) = : (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (6:2:17) holds. (d) Let k > 0. If 2= EG ; then the transform G2 is one-to-one on L;r and there hold ; G2 (L;r ) = I0+; k;(1; )=k;1 (L;r )
(6.4.4)
G2 (L;r ) = I;;;k;( ;1)=k (L;r )
(6.4.5)
for m > 0; and for n > 0. If 2 EG ; then G2 (L;r ) is a subset of the right-hand sides of (6:4:4) and (6:4:5) in the respective cases. (e) If f 2 L;r and 2 C ; then G2f is given in (6:4:1) for Re() > ;; while in (6:4:2) for Re() < ; . Furthermore G2 f is given in (6.2.2).
Theorem 6.29. Let a = 0; 6= 0; < 1 ; < ; 1 < r < 1 and (1 ; ) +
Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform G2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; (1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform G2 is one-to-one on L;r and there holds the equality (6:2:12) for f 2 L;2 and Re(s) = : (c) If f 2 L;r and g 2 L1;;s with 1 < s < 1; 1=r +1=s = 1 and (1; )+Re() 5 1=2; max[ (r); (s)]; then the relation (6:2:17) holds. (d) If 2= EG ; then the transform G2 is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there holds
G2(L;r ) = M;=;1=2H ;;
L3=2; +Re()=;r :
(6.4.6)
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6:4:6): (e) If f 2 L;r ; 2 C and (1 ; ) + Re() 5 1=2 ; (r); then G2f is given in (6:4:1) for Re() > ;; while in (6:4:2) for Re() < ; . If (1 ; ) + Re() < 0; G2 f is given in
6.4.
G2-Transform on the Space L;r
181
(6.2.2). From Theorem 5.17 we have the L;r -theory of the transform G2 in (6.2.2) with a > 0:
Theorem 6.30. Let a > 0; < 1 ; < and 1 5 r 5 s 5 1: (a) The transform G2 de ned on L;2 can be extended to L;r as an element of [L;r ; L;s].
If 1 5 r 5 2; then G2 is a one-to-one transform from L;r onto L;s . (b) If f 2 L;r and g 2 L1;;s0 with 1=s + 1=s0 = 1; then the relation (6:2:17) holds.
When a > 0; from Theorems 5.18{5.22 we obtain the characterization of the boundedness and the range of G2 on L;r in ve di erent cases.
Theorem 6.31. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; < and ! = + a1 ; a2 +1
and let 1 < r < 1: (a) If 2= EG ; or if 1 5 r 5 2; then the transform G2 is one-to-one on L;r . (b) If Re(!) = 0 and 2= EG ; then
G2(L;r ) =
L;a1 ;1; L;a2 ; +!=a2
(L;r ):
(6.4.7)
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6:4:7): (c) If Re(!) < 0 and 2= EG ; then
;! G2(L;r ) = I0+;1 =a ;(1; )a;1 L;a ;1; L;a ; (L;r ):
1
1
1
2
(6.4.8)
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6.4.8).
Theorem 6.32. Let a1 > 0; a2 = 0; m > 0; < 1 ; < and ! = + a1 + 1=2 and let
1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G2 is one-to-one on L;r . (b) If Re(!) = 0 and 2= EG ; then
G2(L;r ) = L;a;1; +!=a (L1;;r ):
(6.4.9)
;! G2(L;r ) = I0+;1 =a ;(1; )a;1 L;a ;1; (L1;;r ):
(6.4.10)
1
1
When 2 EG ; G1 (L;r ) is a subset of the right-hand side of (6:4:9): (c) If Re(!) < 0 and 2= EG ; then
1
1
1
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6.4.10).
Theorem 6.33. Let a1 = 0; a2 > 0; n > 0; < 1 ; < and ! = ; a2 + 1=2 and let
1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G2 is one-to-one on L;r . (b) If Re(!) = 0 and 2= EG ; then
G2(L;r ) = La;1; ;!=a (L1;;r ): 2
2
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6:4:11):
(6.4.11)
182
G-Transform and Modi ed G-Transforms on the Space L;r
Chapter 6.
(c) If Re(!) < 0 and 2= EG ; then
G2(L;r ) = I;;;1!=a;a( ;1)La;1; (L1;;r ):
2
(6.4.12)
2
2
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6.4.12).
Theorem 6.34. Let a > 0; a1 > 0; a2 < 0; < 1 ; < and let 1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G2 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
If 2= EH ; then
(6.4.13)
aRe() = (r) + 2a2 ( ; 1) + Re(); Re( ) > ; 1; Re( ) < 1 ; :
(6.4.14) (6.4.15) (6.4.16)
G2(L;r ) = M;1=2;!=(2a)H 2a;2a+!;1La;1=2;+!=(2a)
2
2
2
2
L ;1=2;Re(!)=(2a2 );r :
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6.4.17).
(6.4.17)
Theorem 6.35. Let a > 0; a1 < 0; a2 > 0; < 1 ; < and let 1 < r < 1: (a) If 2= EG ; or if 1 < r 5 2; then the transform G2 is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
If 2= EG ; then
(6.4.18)
aRe() = (r) ; 2a1 + + Re(); Re( ) > ; ; Re( ) < :
(6.4.19) (6.4.20) (6.4.21)
G2(L;r ) = M1=2+!=(2a)H ;2a;2a+!;1L;a ;1=2+;!=(2a)
1
1
1
1
L +1=2+Re(!)=(2a1 );r :
When 2 EG ; G2 (L;r ) is a subset of the right-hand side of (6.4.22).
(6.4.22)
The inversion formulas for the transform G2 in (6.2.2) on L;r when a = 0, are obtained from (5.3.25) and (5.3.26) under the condition (6.1.4), and take the forms d x+1 f (x) = x; dx # " Z 1 ;; ;a n+1 ; ; ;ap ; ;a1; ; ;an 1 (G2 f )(t)dt (6.4.23) x q ; m;p ; n +1 G p+1;q+1 t 0 ;bm+1 ; ; ;bq ; ;b1; ; ;bm; ; ; 1 t
G; -Transform on the Space L;r
6.5.
and
d x+1 f (x) = ;x; dx
1 q;m+1;p;n G p+1;q+1 0
Z
"
183
# 1 (G2f )(t)dt: (6.4.24) x ;an+1 ; ; ;ap; ;a1 ; ; ;an; ; t ; ; 1; ;bm+1; ; ;bq ; ;b1; ; ;bm t
The validity of (6.4.23) and (6.4.24) are deduced from Theorems 5.23 and 5.24, where and 0 are given in (6.1.5), (6.1.6), (6.1.9), (6.1.10), (6.1.11), (6.1.37) and (6.1.38), respectively.
a; ; ; ; ; 0
Theorem 6.36. Let a = 0; < 1 ; < and 0 < < 0; and let 2 C . (a) If (1 ; ) + Re() = 0 and f 2 L;2; then the inversion formula (6:4:23) holds for
Re() > ; 1 and (6:4:24) for Re() < ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (6:4:23) holds for Re() > ; 1 and (6:4:24) for Re() < ; 1.
Theorem 6.37. Let a = 0; 1 < r < 1 and (1 ; ) + Re() 5 1=2 ; (r); and let
2 C.
(a) If > 0; m > 0; < 1 ; < ; 0 < < min[ 0; fRe( + 1=2)=g + 1] and if
f 2 L;r ; then the inversion formulas (6:4:23) and (6:4:24) hold for Re() > ; 1 and for Re() < ; 1; respectively. (b) If < 0; n > 0; < 1 ; < ; max[ 0; fRe( + 1=2)=g + 1] < < 0 and if f 2 L;r ; then the inversion formulas (6:4:23) and (6:4:24) hold for Re() > ; 1 and for Re() < ; 1; respectively.
6.5. G; -Transform on the Space L;r
We consider the transform G; de ned in (6.2.3). From the results in Section 5.4 we obtain L;2 - and L;r -theory for the transform G; .The rst result follows from Theorem 5.25.
Theorem 6.38. We suppose that (a) < 1 ; + Re() < and that either of the conditions (b) a > 0; or (c) a = 0; [1 ; + Re()] + Re() 5 0 holds. Then we have
the following results: (i) There is a one-to-one transform G; 2 [L;2; L1;+Re(;);2] such that (6:2:13) holds for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . If a = 0; [1 ; + Re()] + Re() = 0 and ; Re() 2= EG ; then the transform G; maps L;2 onto L1;+Re(;);2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation (6:2:18) holds for G;. (iii) Let 2 C and f 2 L;2: If Re() > ; + Re(); then G;f is given by # " Z ;; ; a ; ; a 1 m;n+1 1 p d +1 ; G; f (x) = x dx x 0 Gp+1;q+1 xt b ; ; b ; ; ; 1 t f (t)dt: 1 q When Re() < ; + Re();
(6.5.1)
184
Chapter 6.
G;f
(x) = ;x;
G-Transform and Modi ed G-Transforms on the Space L;r
" # d x+1 Z 1 Gm+1;n xt a1 ; ; ap; ; tf (t)dt: dx 0 p+1;q+1 ; ; 1; b1; ; bq
(6.5.2)
(iv) The transform G; is independent of in the sense that; if and e satisfy (a), and (b) or (c), and if the transforms G; and Ge ; are de ned in L;2 and Le ;2; respectively; by (6:2:13); then G; f = Ge ; f for f 2 L;2 \ Le ;2. (v) If a > 0 or if a = 0; [1 ; + Re()] + Re() < 0, then for f 2 L;2; G;f is given in (6.2.3). If a = 0, Theorems 5.26{5.28 give the mapping properties and the range of G; on L;r .
Theorem 6.39. Let a = = 0; Re() = 0 and < 1 ; + Re() < : Let 1 < r < 1. (a) The transform G; de ned on L;2 can be extended to L;r as an element of
[L;r ; L1; +Re(;);r ]. (b) If 1 < r 5 2; then the transform G; is one-to-one on L;r and there holds the equality (6:2:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ). (c) If f 2 L;r and g 2 L+Re(;);r0 with r0 = r=(r ; 1); then the relation (6:2:18) holds. (d) If ; Re() 2= EG ; then the transform G; is one-to-one on L;r and there holds
G;(L;r ) = L1;+Re(;);r : (6.5.3) (e) If f 2 L;r and 2 C ; then G; f is given in (6:5:1) for Re() > ; + Re(); while
in (6:5:2) for Re() < ; + Re():
Theorem 6.40. Let a = = 0; Re() < 0 and < 1 ; + Re() < ; and let either
m > 0 or n > 0. Let 1 < r < 1. (a) The transform G; de ned on L;2 can be extended to L;r as an element of [L;r ; L1; +Re(;);s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform G; is one-to-one on L;r and there holds the equality (6:2:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ). (c) If f 2 L;r and g 2 L+Re(;);s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (6:2:18) holds. (d) Let k > 0. If ; Re() 2= EG ; then the transform G; is one-to-one on L;r and there hold
G; (L;r ) = I;;;k;(; )=k
L1; +Re(;);r
(6.5.4)
for m > 0; and ; G; (L;r ) = I0+; (6.5.5) k;( ;)=k;1 L1; +Re(;);r for n > 0. When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand sides of (6:5:4) and
(6:5:5) in the respective cases. (e) If f 2 L;r and 2 C ; then G; f is given in (6:5:1) for Re() > ; + Re(); while in (6:5:2) for Re() < ; + Re(). Furthermore G; f is given in (6.2.3).
6.5.
G; -Transform on the Space L;r
185
Theorem 6.41. Let a = 0; 6= 0; < 1 ; + Re() < ; 1 < r < 1 and [1 ; +
Re()] + Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform G; de ned on L;2 can be extended to L;r as an element of [L;r ; L1; +Re(;);s ] for all s with r 5 s < 1 such that s0 = f1=2;[1; +Re()];Re()g;1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform G; is one-to-one on L;r and there holds the equality (6:2:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ). (c) If f 2 L;r and g 2 L+Re(;);s with 1 < s < 1; 1=r +1=s = 1 and [1 ; +Re()]+ Re() 5 1=2 ; max[ (r); (s)]; then the relation (6:2:18) holds. (d) If ; Re() 2= EG ; then the transform G; is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re() > ;1 and there holds
G; (L;r ) = M+=+1=2 H ; L;1=2;Re()=;Re();r : When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6:5:6):
(6.5.6)
and [1 ; + Re()] + Re() 5 1=2 ; (r); then G; f is given in (6:5:1) for Re() > ; + Re(); while in (6:5:2) for Re() < ; + Re(). If [1 ; + Re()] + Re() < 0; G; f is given in (6.2.3).
(e) If f 2
L;r ; 2
C
From Theorem 5.29 we obtain the L;r -theory of the transform G; in (6.2.3) with a > 0.
Theorem 6.42. Let a > 0; < 1 ; + Re() < and 1 5 r 5 s 5 1: (a) The transform G; de ned on L;2 can be extended to L;r as an element of
[L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then G; is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If f 2 L;r and g 2 L;Re(;);s0 with 1=s +1=s0 = 1; then the relation (6:2:18) holds. For a > 0; Theorems 5.30{5.34 imply the characterization theorems of the boundedness and the range of G; on L;r :
Theorem 6.43. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; + Re() < and
! = + a1 ; a2 + 1 and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 5 r 5 2; then the transform G; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EG ; then
G;(L;r ) = La; ; La;1; +;!=a L1;+Re(;);r : When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6:5:7):
(6.5.7)
G;(L;r ) = I;;;1!=a;a(; )La; ; La;1; + L1;+Re(;);r : When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6.5.8).
(6.5.8)
1
2
2
(c) If Re(!) < 0 and ; Re() 2= EG ; then
1
1
1
2
Theorem 6.44. Let a1 > 0; a2 = 0; m > 0; < 1 ; +Re() < and ! = + a1 +1=2
and let 1 < r < 1:
186
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
(a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EG ; then
G; (L;r ) = La; ;;!=a L;Re(;);r : When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6:5:9):
1
(6.5.9)
1
(c) If Re(!) < 0 and ; Re() 2= EG ; then
G; (L;r ) = I;;;1!=a;a(; )La; ; L;Re(;);r : When ; Re() 2 EG;! ; G; (L;r ) is a subset of the right-hand side of (6.5.10).
1
1
1
(6.5.10)
Theorem 6.45. Let a1 = 0; a2 > 0; n > 0; < 1 ; + Re() < and ! = ; a2 + 1=2
and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EG ; then
G; (L;r ) = L;a; ;+!=a L;Re(;);r : When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6:5:11):
(6.5.11)
;! G;(L;r ) = I0+;1 =a ;a ( ;);1 L;a ; ; L ;Re(;);r : When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6.5.12).
(6.5.12)
2
2
(c) If Re(!) < 0 and ; Re() 2= EG ; then
2
2
2
Theorem 6.46. Let a > 0; a1 > 0; a2 < 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
(6.5.13)
aRe() = (r) + 2a2[ ; Re() ; 1] + Re(); Re( ) > ; Re() ; 1; Re( ) < 1 ; + Re():
(6.5.14) (6.5.15) (6.5.16)
If ; Re() 2= EG ; then
G; (L;r ) = M+1=2+!=(2a)H ;2a;2a+!;1L;a;1=2+;!=(2a)
2
2
2
2
L3=2; +Re(!)=(2a2)+Re();r :
(6.5.17)
When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6.5.17).
Theorem 6.47. Let a > 0; a1 < 0; a2 > 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G; is one-to-one on L;r .
6.5.
G; -Transform on the Space L;r
187
(b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(6.5.18)
aRe( ) = (r) ; 2a1 [ ; Re()] + + Re(); Re( ) > ; + Re(); Re( ) < ; Re():
(6.5.19) (6.5.20) (6.5.21)
If ; Re() 2= EG ; then
G; (L;r ) = M;1=2;!=(2a)H 2a;2a+!;1 La;1=2;+!=(2a)
1
1
1
1
L1=2; ;Re(!)=(2a1);Re();r :
(6.5.22)
When ; Re() 2 EG ; G; (L;r ) is a subset of the right-hand side of (6.5.22). The inversion formulas for the transform G; in (6.2.3) on L;r when a = 0, are obtained from (5.4.25) and (5.4.26) under the relation (6.1.4), and take the form d x+1 f (x) = x;; dx " # Z 1 ;; ;a n+1 ; ; ;ap; ;a1 ; ; ;an q ; m;p ; n +1 H p+1;q+1 xt 0 ;bm+1; ; ;bq; ;b1; ; ;bm; ; ; 1
t; G; f (t)dt
or
d x+1 f (x) = ;x;; dx
1 q;m+1;p;n " H p+1;q+1 xt 0
Z
;an+1 ; ; ;ap; ;a1; ; ;an; ; ; ; 1; ;bm+1; ; ;bq; ;b1; ; ;bm t; G; f (t)dt:
(6.5.23)
#
(6.5.24)
The conditions for the validity of (6.5.23) and (6.5.24) follow from Theorems 5.35 and 5.36, where a ; ; ; ; ; 0 and 0 are given in (6.1.5), (6.1.6), (6.1.9){(6.1.11), (6.1.37) and (6.1.38), respectively.
Theorem 6.48. Let a = 0; < 1 ; + Re() < and 0 < ; Re() < 0; and let
2 C.
(a) If [1 ; + Re()] + Re() = 0 and f 2 L;2; then the inversion formula (6:5:23)
holds for Re() > ; Re() ; 1 and (6:5:24) for Re() < ; Re() ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (6:5:23) holds for Re() > ; Re() ; 1 and (6:5:24) for Re() < ; Re() ; 1.
188
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
Theorem 6.49. Let a = 0; 1 < r < 1 and [1 ; + Re()] + Re() 5 1=2 ; (r); and
let 2 C . (a) If > 0; m > 0; < 1; +Re() < ; 0 < ;Re() < min[ 0; fRe(+1=2)=g+1] and if f 2 L;r ; then the inversion formulas (6:5:23) and (6:5:24) hold for Re() > ; Re() ; 1 and for Re() < ; Re() ; 1; respectively. (b) If < 0; n > 0; < 1; +Re() < ; max[ 0; fRe(+1=2)=g+1] < ;Re() < 0 and if f 2 L;r ; then the inversion formulas (6:5:23) and (6:5:24) hold for Re() > ; Re() ; 1 and for Re() < ; Re() ; 1; respectively.
Remark 6.1. The results in this section generalize those in Section 6.1. Namely, Theorems 6.1{6.12 follow from Theorems 6.37 and 6.38 when = = 0: 6.6. G1; -Transform on the Space L;r
Let us study the transform G1; de ned in (6.2.4). The theory of the transform G1; on the spaces L;2 and L;r is obtained from that in Section 5.5, for which the parameters are de ned in (6.1.5){(6.1.11).
Theorem 6.50. We suppose that (a) < ; Re() < and that either of the conditions (b) a > 0; or (c) a = 0; [ ; Re()] + Re() 5 0 holds. Then we have the
following results: (i) There is a one-to-one transform G1; 2 [L;2; L;Re(+);2 ] such that (6:2:14) holds for Re(s) = ; Re( + ) and f 2 L;2 . If a = 0; [ ; Re()]+Re() = 0 and 1 ; +Re() 2= EG ; then the transform G1; maps L;2 onto L ;Re(+);2 . (ii) If f 2 L;2 and g 2 L1;+Re(+);2; then the relation (6:2:19) holds for G1;. (iii) Let 2 C and f 2 L;2: If Re() > ; Re() ; 1; then G1;f is given by Z 1 +1 x ;; a1; ; ap t;1 f (t)dt: G1; f (x) = x; dxd x+1 0 Gm;n p+1;q+1 t b1; ; bq; ; ; 1
"
#
(6.6.1)
When Re() < ; Re() ; 1; Z 1 a ; ; a ; ; G1;f (x) = ;x; dxd x+1 0 Gmp+1+1;q;n+1 xt ;1 ; 1; bp ; ; b 1 q
"
#
t;1 f (t)dt:
(6.6.2)
(iv) The transform G1; is independent of in the sense that, if and satisfy (a), e
and either (b) or (c), and if the transforms G1; and g G1; are de ned in L;2 and Le;2; respectively; by (6:2:14); then G1; f = g G1; f for f 2 L;2 \ Le;2. (v) If a > 0 or if a = 0; [ ; Re()] + Re() < 0; then for f 2 L;2; G1; f is given in
(6.2.4).
If a = 0; Theorems 5.38{5.40 yield the mapping properties and the range of G1; on L;r .
Theorem 6.51. Let a = = 0; Re() = 0 and < ; Re() < : Let 1 < r < 1.
6.6.
G1; -Transform on the Space L;r
(a) The transform G1; de ned on
189 L;2 can be extended to L;r as an element of
[L;r ; L ;Re(+);r ]. (b) If 1 < r 5 2; then the transform G1; is one-to-one on L;r and there holds the equality (6:2:14) for f 2 L;r and Re(s) = ; Re( + ). (c) If f 2 L;r and g 2 L1;+Re(+);r0 with r0 = r=(r ; 1); then the relation (6:2:19) holds. (d) If 1 ; + Re() 2= EG ; then the transform G1; is one-to-one on L;r and there holds
G1; (L;r ) = L;Re(+);r : (6.6.3) (e) If f 2 L;r and 2 C ; then G1;f is given in (6:6:1) for Re() > ; Re() ; 1; while
in (6:6:2) for Re() < ; Re() ; 1:
Theorem 6.52. Let a = = 0; Re() < 0 and < ; Re() < ; and let either m > 0
or n > 0. Let 1 < r < 1. (a) The transform G1; de ned on L;2 can be extended to L;r as an element of [L;r ; L ;Re(+);s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform G1; is one-to-one on L;r and there holds the equality (6:2:14) for f 2 L;r and Re(s) = ; Re( + ). (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (6:2:19) holds. (d) Let k > 0. If 1 ; + Re() 2= EG ; then the transform G1; is one-to-one on L;r and there hold
G1; (L;r ) = I;;;k;(; )=k
L ;Re(+);r
(6.6.4)
for m > 0; and ; G1; (L;r ) = I0+; (6.6.5) k;( ;)=k;1 L ;Re(+);r for n > 0. If 1 ; + Re() 2 EG ; then G1; (L;r ) is a subset of the right-hand sides of (6:6:4)
and (6:6:5) in the respective cases. (e) If f 2 L;r and 2 C ; then G1;f is given in (6:6:1) for Re() > ; Re() ; 1; while in (6:6:2) for Re() < ; Re() ; 1. Furthermore G1; f is given in (6.2.4).
Theorem 6.53. Let a = 0; 6= 0; m > 0; < ; Re() < ; 1 < r < 1 and
[ ; Re()] + Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform G1; de ned on L;2 can be extended to L;r as an element of [L;r ; L ;Re(+);s ] for all s with r 5 s < 1 such that s0 = [1=2 ; f ; Re()g ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform G1; is one-to-one on L;r and there holds the equality (6:2:14) for f 2 L;r and Re(s) = ; Re( + ). (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1; 1=r + 1=s = 1 and [ ; Re()] + Re() 5 1=2 ; max[ (r); (s)]; then the relation (6:2:19) holds. (d) If 1 ; + Re() 2= EG ; then the transform G1; is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there
190
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
holds
G1; (L;r ) = M+=+1=2 H ; L1=2;;Re()=;Re();r : (6.6.6) When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the set on the right-hand side of (6:6:6): (e) If f 2 L;r ; 2 C and [ ; Re()]+Re() 5 1=2 ; (r); then G1;f is given in (6:6:1)
for Re() > ;Re();1; while in (6:6:2) for Re() < ;Re();1. If [ ;Re()]+Re() < 0; G1; f is given in (6.2.4). From Theorem 5.41 we obtain the L;r -theory of the transform G1; in (6.2.4) with a > 0:
Theorem 6.54. Let a > 0; < ; Re() < and 1 5 r 5 s 5 1: (a) The transform G1; de ned on L;2 can be extended to L;r as an element
of [L;r ; L ;Re(+);s ]. If 1 5 r 5 2; then G1; is a one-to-one transform from L;r onto L ;Re(+);s . (b) If f 2 L;r and g 2 L1;+Re(+);s0 with 1=s+1=s0 = 1; then the relation (6:2:19) holds. By virtue of Theorems 5.42{5.44 we characterize the boundedness and the range of G1; on L;r in ve cases.
Theorem 6.55. Let a1 > 0; a2 > 0; m > 0; n > 0; < ; Re() < and
! = + a1 ; a2 + 1 and let 1 < r < 1: (a) If 1 ; + Re() 2= EG ; or if 1 5 r 5 2; then the transform G1; is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; + Re() 2= EG ; then
G1; (L;r ) = La; ; La;1; +;!=a L;Re(+);r : When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6:6:7):
(6.6.7)
G1; (L;r ) = I;;;1!=a;a(; )La; ; La;1; + L;Re(+);r : When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6.6.8).
(6.6.8)
1
2
2
(c) If Re(!) < 0 and 1 ; + Re() 2= EG ; then
1
1
1
2
Theorem 6.56. Let a1 > 0; a2 = 0; m > 0; < ; Re() < and ! = + a1 + 1=2
and let 1 < r < 1: (a) If 1 ; + Re() 2= EG ; or if 1 < r 5 2; then the transform G1; is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; + Re() 2= EG ; then
G1;(L;r ) = La; ;;!=a L1;+Re(+);r : When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6:6:9):
1
1
(c) If Re(!) < 0 and 1 ; + Re() 2= EG ; then
(6.6.9)
G1; (L;r ) = I;;;1!=a;a(; )La; ; L1;+Re(+);r : (6.6.10) When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6.6.10).
1
1
1
6.6.
G1; -Transform on the Space L;r
191
Theorem 6.57. Let a1 = 0; a2 > 0; n > 0; < ; Re() < and ! = ; a2 + 1=2
and let 1 < r < 1: (a) If 1 ; + Re() 2= EG ; or if 1 < r 5 2; then the transform G1; is one-to-one on L;r . (b) If Re(!) = 0 and 1 ; + Re() 2= EG ; then
G1; (L;r ) = L;a; ;+!=a L1;+Re(+);r : (6.6.11) When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6:6:11):
2
2
(c) If Re(!) < 0 and 1 ; + Re() 2= EG ; then
;! G1; (L;r ) = I0+;1 =a ;a ( ;);1L;a ; ; L1; +Re(+);r : If 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6.6.12).
2
2
2
(6.6.12)
Theorem 6.58. Let a > 0; a1 > 0; a2 < 0; < ; Re()) < and let 1 < r < 1: (a) If 1 ; + Re() 2= EG ; or if 1 < r 5 2; then the transform G1; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
(6.6.13)
a Re() = (r) + 2a2 [ ; Re()] + Re(); Re( ) > ; + Re(); Re( ) < ; Re(): If 1 ; + Re() 2= EG ; then G1; (L;r ) = M+1=2+!=(2a2)H ;2a2 ;2a2+!;1L;a;1=2+;!=(2a2)
(6.6.14) (6.6.15) (6.6.16)
L +1=2+Re(!)=(2a2);Re();r :
(6.6.17)
When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6.6.17).
Theorem 6.59. Let a > 0; a1 < 0; a2 > 0; < ; Re() < and let 1 < r < 1: (a) If 1 ; + Re() 2= EG ; or if 1 < r 5 2; then the transform G1; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(6.6.18)
aRe( ) = (r) ; 2a1 [ ; Re()] + + Re(); Re( ) > ; + Re(); Re( ) < ; Re(): If 1 ; + Re() 2= EG ; then G1; (L;r ) = M;1=2;!=(2a1)H 2a1;2a1+!;1 La;1=2;+!=(2a1)
(6.6.19) (6.6.20) (6.6.21)
L ;1=2;Re(!)=(2a1);Re();r :
(6.6.22)
192
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
When 1 ; + Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6.6.22). The inversion formulas for the transform G1; in (6.2.4) on L;r , when a = 0, are obtained from (5.5.23) and (5.5.24) under the condition (6.1.4): d x;;1 f (x) = ;x+1; dx # " Z 1 ;; ;a n+1 ; ; ;ap; ;a1 ; ; ;an t q ; m;p ; n +1 G p+1;q+1 x 0 ;bm+1; ; ;bq; ;b1; ; ;bm; ; ; 1
t; G1;f (t)dt
or
d x;;1 f (x) = x+1; dx
1 q;m+1;p;n G p+1;q+1 0
Z
"
t ;an+1 ; ; ;ap; ;a1; ; ;an ; ; x ; ; 1; ;bm+1 ; ; ;bq; ;b1; ; ;bm
t; G1;f (t)dt:
(6.6.23)
#
(6.6.24)
Theorems 5.47 and 5.48 deduce the validity of the inversion formulas (6.6.23) and (6.6.24).
Theorem 6.60. Let a = 0; < ; Re() < and 0 < 1 ; + Re() < 0; and let
2 C.
(a) If [ ; Re()] + Re() = 0 and f 2 L;2 ; then the inversion formula (6:6:23) holds
for Re() > ; + Re() and (6:6:24) for Re() < ; + Re(). (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (6:6:23) holds for Re() > ; + Re() and (6:6:24) for Re() < ; + Re().
Theorem 6.61. Let a = 0; 1 < r < 1 and [ ; Re()] + Re() 5 1=2 ; (r); and let
2 C.
(a) If > 0; m > 0; < ;Re() < ; 0 < 1; +Re() < min[ 0; fRe(+1=2)=g+1]
and if f 2 L;r ; then the inversion formulas (6:6:23) and (6:6:24) hold for Re() > ; +Re() and for Re() < ; + Re(); respectively. (b) If < 0; n > 0; < ;Re() < ; max[ 0; fRe(+1=2)=g+1] < 1; +Re() < 0 and if f 2 L;r ; then the inversion formulas (6:6:23) and (6:6:24) hold for Re() > ; +Re() and for Re() < ; + Re(); respectively.
Remark 6.2. The results in this section generalize those in Section 6.3. That is, Theorems 6.13{6.24 follow from Theorems 6.48{6.60 when = = 0:
6.7.
G2; -Transform on the Space L;r
193
6.7. G2; -Transform on the Space L;r Lastly we treat the transform G2; de ned in (6.2.5) by using the results in Section 5.6.
Theorem 6.62. We suppose that (a) < 1 ; + Re() < and that either of the conditions (b) a > 0; or (c) a = 0; [1 ; + Re()] + Re() 5 0 holds. Then we have
the following results: (i) There is a one-to-one transform G2; 2 [L;2; L;Re(+);2] such that (6:2:15) holds for Re(s) = ; Re( + ) and f 2 L;2 . If a = 0; [1 ; + Re()] + Re() = 0 and ; Re() 2= EG ; then the transform G2; maps L;2 onto L ;Re(+);2 . (ii) If f 2 L;2 and g 2 L1;+Re(+);2; then the relation (6:2:20) holds for G2;. (iii) Let 2 C and f 2 L;2: If Re() > ; + Re(); then G2;f is given by
" # Z 1 ;; a ; ; a 1 p t d m;n +1 ; ; 1 2 + +1 G t f (t)dt: (6.7.1) G;f (x) = ;x dx x 0 p+1;q+1 x b1; ; bq ; ; ; 1 When Re() < ; + Re(); " # Z 1 a ; ; a ; ; 1 p t d m +1 ;n ; ; 1 2 + +1 Gp+1;q+1 x t f (t)dt: (6.7.2) G; f (x) = x dx x 0 ; ; 1; b1; ; bq
(iv) The transform G2; is independent of in the sense that; if and satisfy (a), e
and either (b) or (c), and if the transforms G2; and G2; are de ned in L;2 and Le ;2 ; respectively; by (6:2:15); then G2; f = g G2; f for f 2 L;2 \ Le;2. (v) If a > 0 or if a = 0; [1 ; + Re()] + Re() < 0; then for f 2 L;2; G2;f is given in (6.2.5). g
Theorems 5.50{5.52 lead to the mapping properties and the range of G2; on L;r for a > 0.
Theorem 6.63. Let a = = 0; Re() = 0 and < 1 ; + Re() < : Let 1 < r < 1. (a) The transform G2; de ned on L;2 can be extended to L;r as an element of [L;r ;
L ;Re(+);r ].
(b) If 1 < r 5 2; then the transform G2; is one-to-one on L;r and there holds the
equality (6:2:15) for f 2 L;r and Re(s) = ; Re( + ). (c) If f 2 L;r and g 2 L1;+Re(+);r0 with r0 = r=(r ; 1); then the relation (6:2:20) holds. (d) If ; Re() 2= EG ; then the transform G2; is one-to-one on L;r and there holds
G2; (L;r ) = L;Re(+);r : (6.7.3) (e) If f 2 L;r and 2 C ; then G2; f is given in (6:7:1) for Re() > ; + Re(); while
in (6:7:2) for Re() < ; + Re():
Theorem 6.64. Let a = = 0; Re() < 0 and < 1 ; + Re() < ; and let either
m > 0 or n > 0. Let 1 < r < 1.
194
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
(a) The transform G2; de ned on L;2 can be extended to L;r as an element of [L;r ;
L ;Re(+);s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then the transform G2; is one-to-one on L;r and there holds the equality (6:2:15) for f 2 L;r and Re(s) = ; Re( + ). (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re();
then the relation (6:2:20) holds. (d) Let k > 0. If ; Re() 2= EG ; then the transform G2; is one-to-one on L;r and there hold ; G2; (L;r ) = I0+; k;(1; ;)=k;1
L ;Re(+);r
(6.7.4)
for m > 0; and
G2; (L;r ) = I;;;k;( +;1)=k L;Re(+);r (6.7.5) for n > 0. When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand sides of (6:7:4) and
(6:7:5) in the respective cases. (e) If f 2 L;r and 2 C ; then G2; f is given in (6:7:1) for Re() > ; + Re(); while in (6:7:2) for Re() < ; + Re(). Furthermore G2; f is given in (6:2:5):
Theorem 6.65. Let a = 0; 6= 0; < 1 ; + Re() < ; 1 < r < 1 and [1 ; +
Re()] + Re() 5 1=2 ; (r): Assume that m > 0 if > 0 and n > 0 if < 0. (a) The transform G2; de ned on L;2 can be extended to L;r as an element of [L;r ; L ;Re(+);s ] for all s with r 5 s < 1 such that s0 = [1=2;f1; +Re()g ;Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform G2; is one-to-one on L;r and there holds the equality (6:2:15) for f 2 L;r and Re(s) = ; Re( + ). (c) If f 2 L;r and g 2 L1;+Re(+);s with 1 < s < 1; 1=r + 1=s = 1 and [ ; Re()] + Re() 5 1=2 ; max[ (r); (s)]; then the relation (5:1:20) holds. (d) If ; Re() 2= EG ; then the transform G2; is one-to-one on L;r . If we set = ; ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re() > ;1 and there holds
G2(L;r ) = M;=;1=2H ;; L3=2;+Re()=+Re();r : (6.7.6) When ; Re() 2 EG ; G2; (L;r ) is a subset of the set on the right-hand side of (6:7:6): (e) If f 2 L;r ; 2 C and [1 ; + Re()] + Re() 5 1=2 ; (r); then G2; f is
given in (6:7:1) for Re() > ; + Re(); while in (6:7:2) for Re() < ; + Re(). If [1 ; + Re()] + Re() < 0; G2; f is given in (6.2.5).
From Theorem 5.53 we have the L;r -theory of the transform G2; in (5.2.5) with a > 0 in L;r -spaces.
Theorem 6.66. Let a > 0; < 1 ; + Re() < and 1 5 r 5 s 5 1: (a) The transform G2; de ned on L;2 can be extended to L;r as an element of
[L;r ; L ;Re(+);s ]. If 1 5 r 5 2; then L ;Re(+);s .
G2; is a one-to-one transform from L;r onto
6.7.
G2; -Transform on the Space L;r
195
(b) If f 2 L;r and g 2 L1;+Re(+);s0 with 1=s+1=s0 = 1; then the relation (6:2:20) holds. Now we have the characterization theorems from Theorems 5.54{5.58 of the boundedness and the range of G2; on L;r .
Theorem 6.67. Let a1 > 0; a2 > 0; m > 0; n > 0; < 1 ; + Re() < and
! = + a1 ; a2 + 1 and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 5 r 5 2; then the transform G2; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EG ; then
G2;(L;r ) = L;a;1; ; L;a; ++!=a L;Re(+);r : When ; Re() 2 EG ; G1; (L;r ) is a subset of the right-hand side of (6:7:7):
1
2
(6.7.7)
2
(c) If Re(!) < 0 and ; Re() 2= EG ; then
;! G2;(L;r ) = I0+;1 =a ;a (1;; );1 L;a ;1; ; L;a ; + L ;Re(+);r : When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand side of (6.7.8).
1
1
1
2
(6.7.8)
Theorem 6.68. Let a1 > 0; a2 = 0; m > 0; < 1 ; +Re() < and ! = + a1 +1=2
and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G2; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EG ; then
G2; (L;r ) = L;a;1; ;+!=a L1;+Re(+);r : When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand side of (6:7:9):
(6.7.9)
;! G2;(L;r ) = I0+;1 =a ;a (1; ;);1 L;a ;1; ; L1; +Re(+);r : When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand side of (6.7.10).
(6.7.10)
1
1
(c) If Re(!) < 0 and ; Re() 2= EG ; then
1
1
1
Theorem 6.69. Let a1 = 0; a2 > 0; n > 0; < 1 ; + Re() < and ! = ; a2 + 1=2
and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G2; is one-to-one on L;r . (b) If Re(!) = 0 and ; Re() 2= EG ; then
G2;(L;r ) = La;1; ;;!=a L1;+Re(+);r : When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand side of (6:7:11):
(6.7.11)
G2; (L;r ) = I;;;1!=a;a( +;1)La;1; ; L1;+Re(+);r : When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand side of (6.7.12).
(6.7.12)
2
2
(c) If Re(!) < 0 and ; Re() 2= EG ; then
2
2
2
196
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
Theorem 6.70. Let a > 0; a1 > 0; a2 < 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G2; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; 21 ;
(6.7.13)
aRe() = (r) + 2a2[ ; Re() ; 1] + Re(); Re( ) > ; Re() ; 1; Re( ) < 1 ; + Re():
(6.7.14) (6.7.15) (6.7.16)
If ; Re() 2= EG ; then
G2; (L;r ) = M;1=2;!=(2a)H 2a;2a+!;1 La;1=2;+!=(2a)
2
2
2
2
L ;1=2;Re(!)=(2a2);Re();r :
(6.7.17)
When ; Re() 2 EG ; then G2; (L;r ) is a subset of the right-hand side of (6.7.17).
Theorem 6.71. Let a > 0; a1 < 0; a2 > 0; < 1 ; + Re() < and let 1 < r < 1: (a) If ; Re() 2= EG ; or if 1 < r 5 2; then the transform G2; is one-to-one on L;r . (b) Let !; ; 2 C be chosen as ! = a ; ; ; 21 ;
(6.7.18)
aRe( ) = (r) ; 2a1 [ ; Re()] + + Re(); Re( ) > ; + Re(); Re( ) < ; Re():
(6.7.19) (6.7.20) (6.7.21)
If ; Re() 2= EG ; then
G2; (L;r ) = M+1=2+!=(2a)H ;2a;2a+!;1L;a;1=2+;!=(2a)
1
1
1
1
L +1=2+Re(!)=(2a1);Re();r :
(6.7.22)
When ; Re() 2 EG ; G2; (L;r ) is a subset of the right-hand side of (6.7.22). Now we state the inversion formulas for the transform G2; in (6.2.5) on L;r when a = 0. From (5.6.23) and (5.6.24), we nd d x+1 f (x) = x;; dx # " Z 1 ;; ;a n+1 ; ; ;ap; ;a1 ; ; ;an x q ; m;p ; n +1 G p+1;q+1 t 0 ;bm+1; ; ;bq; ;b1; ; ;bm; ; ; 1
t;;1 G2;f (t)dt
(6.7.23)
197
6.8. Bibliographical Remarks and Additional Information on Chapter 6
or
d x+1 f (x) = ;x;; dx
1 q;m+1;p;n G p+1;q+1 0
Z
"
x ;an+1 ; ; ;ap; ;a1; ; ;an ; ; t ; ; 1; ;bm+1 ; ; ;bq; ;b1; ; ;bm
t;;1 G2;f (t)dt:
#
(6.7.24)
The conditions for the validity of (6.7.23) and (6.7.24) follow from Theorems 5.59 and 5.60, where a; ; ; ; ; 0 and 0 are taken as in (6.1.5), (6.1.6), (6.1.9){(6.1.11), (6.1.37) and (6.1.38).
Theorem 6.72. Let a = 0; < 1 ; + Re() < and 0 < ; Re() < 0; and let
2 C.
(a) If [1 ; + Re()] + Re() = 0 and f 2 L;2; then the inversion formula (6:7:23) holds for Re() > ; Re() ; 1 and (6:7:24) for Re() < ; Re() ; 1. (b) If = Re() = 0 and f 2 L;r (1 < r < 1); then the inversion formula (6:7:23) holds for Re() > ; Re() ; 1 and (6:7:24) for Re() < ; Re() ; 1. Theorem 6.73. Let a = 0; 1 < r < 1 and [1 ; + Re()] + Re() 5 1=2 ; (r); and
let 2 C . (a) If > 0; m > 0; < 1; +Re() < ; 0 < ;Re() < min[ 0; fRe(+1=2)=g+1] and if f 2 L;r ; then the inversion formulas (6:7:23) and (6:7:24) hold for Re() > ; Re() ; 1 and for Re() < ; Re() ; 1; respectively. (b) If < 0; n > 0; < 1; +Re() < ; max[ 0; fRe(+1=2)=g+1] < ;Re() < 0 and if f 2 L;r ; then the inversion formulas (6:7:23) and (6:7:24) hold for Re() > ; Re() ; 1 and for Re() < ; Re() ; 1; respectively.
Remark 6.3. The results in this section generalize those in Section 5.3. Namely, Theorems 6.25{6.36 follow from Theorems 6.61{6.72 when = = 0: 6.8. Bibliographical Remarks and Additional Information on Chapter 6 For Section 6.1. The integral transforms with the general Meijer G-function (2.9.1) as kernel were rst considered by Kesarwani [8]{[10] while investigating the G-function as an unsymmetrical Fourier kernel, though earlier he treated in [2] the particular case 3 2 1 Z 1 m ;k + ; ; 7 2 (6.8.1) Gf (x) = G42;;04 64xt 5 f(t)dt: 1 1 0 2m; 0; + ; ; ; ; 2 2 Kesarwani [8] showed that the functions
;1=2 Gm;p Kpm;p +q;m+n (x) = 2 x p+q;m+n
"
a ; ; a ; b ; b 1 p 1 q x2 c1; ; cm ; d1; ; dn
#
(6.8.2)
198
Chapter 6.
G-Transform and Modi ed G-Transforms on the Space L;r
and
;1=2 Gn;q Hqn;q +p;n+m (x) = 2 x q+p;n+m
"
;b ; ; ;b ; ;a ; ;a 1 q 1 p x2 ;d1; ; ;dn; ;c1; ; ;cm
#
(6.8.3)
are a pair of unsymmetrical kernels, since their Mellin transforms (MG1)(s) and (MG2 )(s) satisfy the relation (MG1)(s)(MG2)(1 ; s) = 1, where G1 (x) =
x
Z
0
Kpm;p +q;m+n (t)dt;
G2(x) =
In [9] Kesarwani considered the transform G
Gf (x) = 2
Z
0
1
(xt) ;1=2Gm;p p+q;m+n
and proved its inversion formula f(x + 0) + f(x ; 0) 2 = 2
1
Z
0
(xt) ;1=2Gn;q q+p;n+m
"
x
Z
0
Hqn;q +p;m+n (t)dt:
a1 ; ; ap; b1 ; bq (xt)2 c1 ; ; cm ; d1; ; dn
;b ; ; ;b ; ;a ; ;a 1 q 1 p x2 ;d1 ; ; ;dn; ;c1 ; ; ;cm
"
(6.8.4)
#
#
f(t)dt
(6.8.5)
(Gf)(t)dt;
(6.8.6)
provided that
> 0; n ; p = m ; q = 2 > 0;
p
X
i=1
ai ;
q
X
i=1
bi =
m
X
j =1
cj ;
n
X
j =1
dj ;
; 1 (1 5 i 5 p); Re(b ) > 1 ; (1 5 i 5 q); (6.8.7) Re(ai ) < 2 i 2 ; (1 5 j 5 m); Re(d ) < ; 1 (1 5 j 5 n); Re(cj ) > 1 2 j 2 f(t)t= ;1=2 2 L1 (R+ ) and f(t) is of bounded variation near t = x (x > 0). In [10] Kesarwani established that if the conditions in (6.8.7) are satis ed, and further, Re(ai ) < 1=2 (1 5 i 5 p), Re(bi) > ;1=2 (1 5 i 5 q), Re(cj ) > ;1=2 (1 5 j 5 m), Re(dj ) < 1=2 (1 5 j 5 n) and f(x) 2 L2(R+ ) are assumed, then the formula d Z 1 G (xt)f(t) dt (6.8.8) g(x) = dx 1 t 0 is de ned as a function in L2 (R+ ), and the reciprocal formula d Z 1 G (xt)g(t) dt (6.8.9) f(x) = dx 2 t 0 holds almost everywhere, where G1(x); G2(x) are given in (6.8.4). The special case of the above results by Kesarwani [9], [10] in which q = p, n = m and bi = ;ai , dj = ;cj for each 1 5 i 5 p, 1 5 j 5 m was earlier studied by Fox [2, Theorems 1 and 2]. Fox [2] also indicated that the function " # a ; ; a ; 1 ; ; a ; ; 1 ; ; a 1 p 1 p q;p 1 = G(x) = G2p;2q x (6.8.10) b1; ; bq ; 1 ; ; b1 ; ; 1 ; ; bq with > 0 is a symmetric Fourier kernel. Such a result was also given by Masood and Kapoor [1] in a di erent way.
199
6.8. Bibliographical Remarks and Additional Information on Chapter 6
Kesarwani [12] and Wong and Kesarwani [1] derived necessary and sucient conditions for the pair of functions f(x) 2 L2 (R+ ) and g(x) 2 L2(R+ ) to be the G-transform of each other: f(x) = where G(x) is given by
Z
0
1
G(xt)g(t)dt; g(x) =
G(x) = =2 x( ;1)=2Gq;p 2p;2q
"
1
Z
0
G(xt)f(t)dt;
a ; ; a ; ;a ; ;a 1 p 1 p (x) b1 ; ; bq ; ;b1; ; ;bq
(6.8.11) #
(6.8.12)
with positive > 0 and > 0. Bhise [5] established theorems on functions connected by the G-transform of the form 2 ; 1 ; ;k + m + + 1 3 Z 1 k;m; 2 2 75 f(t)dt: (6.8.13) Gf (x) = G22;;14 64xt 2 2 0 ; + 2m; ; ; ; 2m ; 2 2 2 2 Raj.K. Saxena [1] expressed via this transform the transform containing the Whittaker function W; (x) (see (7.2.2)) in the kernel. R.U. Verma [2] proved Parseval's theorem and some properties for a more general integral transform than (6.8.13) with the G22;;14-function as kernel. Using the technique of the Laplace transform L and its inverse L;1 developed by Fox in [4] and [5], R.U. Verma in [6], [7] and [8] proved the inversion formulas for the G-transforms (6.1.1) with the functions G02;pp;q (x), Gq2+p+m;p n;2q+m (x) and Gq;p;q0 (x) as the kernels, respectively. Using the method developed by Zemanian [6], Misra [3] proved that the real inversion formula for the general G-transform (6.1.1) can be extended to certain spaces of generalized functions. In [4] Misra obtained such a result for the particular case of the G-transform with m = q = 2, n = 1, p = 1 " # Z 1 a 2 ; 0 Gf (x) = G1;2 xt b ; b f(t)dt; (6.8.14) 0 1 2 which is reduced to the Laplace transform (2.5.2) when a = b1 and b2 = 0. Pathak and J.N. Pandey [4] extended the G-transform (6.1.1) to another class of generalized functions. In particular, they established that the inversion formula (6.8.6) due to Kesarwani [9] can be extended to distributions in the sense of weak convergence. The above results were presented in Brychkov and Prudnikov [1, Section 8.1]. O.P. Sharma [2] used the transform (6.8.5) to obtain the formula for the Meijer transform (8.9.1) of the product of two functions f(x) and g(x). Pathak [9] gave two Abelian theorems for the transform (6.8.4) and showed that Abelian theorems for integral transforms such as the Hankel transform H in (8.1.1), the Y -transform in (8.7.1), the Struve transform H in (8.8.1), the Meijer transform K in (8.9.1) and the Hardy transform J; in (8.12.6) follow by suitably specializing the parameters in the kernel Kpm;p +q;m+n (x) given in (6.8.2) (see also Section 8.14 in this connection). The technique of factorization of the G-transform (6.1.1) to representations via simpler G-transforms, together with special tables and notation, were rst developed by Brychkov, Glaeske and Marichev [1], without characterization of conditions and spaces of functions (see also their [2]). The factorization of the G-transform as well as its mapping properties and inversion formulas in the special spaces of functions M;c; 1 and L(2c; ) were proved by Marichev and Vu Kim Tuan [1], [2], Vu Kim Tuan, Marichev and Yakubovich [1] and Vu Kim Tuan [1] (see the results in the bibliography in Sections 36 and 39.1 of the book by Samko, Kilbas and Marichev [1], and in the book by Yakubovich and Luchko [1].). The results of these sections concerning the boundedness, representation, range and inversion of the G-transforms (6.1.1) in L;r -spaces (3.1.3) were proved by Rooney [6]. We obtained these results as the particular cases of the corresponding statements for the H-transforms (3.1.1) presented in Chapters 3 and 4. They basically coincide with those in Rooney [6] if we replace by and take into account the relations (6.8.15) = a2 ; k = a1 ; l = a2 ; = + 2 ;
200
G-Transform and Modi ed G-Transforms on the Space L;r
Chapter 6.
comparing Rooney's notation with ours. We only note that in Theorem 6.4 the representations (6.1.16) and (6.1.17) for any k > 0 generalize those given by Rooney [6, Theorem 6.2] for k = 1; and in Theorems 6.9 and 6.10 the conditions (6.1.26){(6.1.28) and (6.1.31){(6.1.33) for the validity of the relations (6.1.29) and (6.1.34), respectively are more general and simpler than those proved by Rooney [6, Theorems 7.5 and 7.6]. We also indicate that Corollaries 6.10.1, 6.10.2 and 6.11.1, 6.11.2 present the sucient conditions for (6.1.26){ (6.1.28) and (6.1.31){(6.1.33) to hold. For Section 6.2. A series of papers was devoted to investigating the generalizations and the modi cations of the G-transform (6.1.1) which are di erent from those in (6.2.1){(6.2.5). Kesarwani [1] rst considered the modi ed Meijer G-transform of the form
1
22 (xt)+1=2 ;k;m x 4t f(t)dt; 0 2 1 3 1 k ;m ; ; ;k + m + ;k;m (x) = x; G22;;14 4x 2 2 5; ; + 2m; ;2m; 0
G f (x) = 2;
Z
(6.8.16)
which reduces to the Hankel transform H f in (8.1.1) when k + m = 1=2. Kesarwani [1] proved the inversion formula for such a transform and discussed self-reciprocal functions connected with the kernel of this transform. K.C. Sharma [3] de ned the integral transform
a ; ; a ; c ; ; c 1 n 1 m G f (x) = e;nxt=4G4m;n+n;m+n+2 axt b1 ; ; b4; d1; ; dm+n;2 0
Z
"
1
#
f(t)dt
(6.8.17)
with 0 5 m 5 3, n = 0, m + n = 2, n 2 N0 and proved the inversion formula for such a transform by using the Mellin transform M and its inverse M;1 . For such a transform with m = 2 and n = 0 S.P. Goyal [2] obtained three chains connecting the originals and their images. R.P. Goyal [2] and Golas [1] gave the conditions of convergence and uniform convergence for the modi ed G-transform " # Z 1 a ; ; a ; 1 p m;n ; bxt G f (x) = e Gp+1;q axt d (t): (6.8.18) b1; ; bq 0 Misra [2] generalized part of the Abelian theorems for the Laplace transform given in Widder [1, p.181] to the G-transform # " Z 1 ; ; a ; ; a 1 p 2 m;n +1 ; bxt f(t)dt (6.8.19) e Gp+1;q xt G f (x) = b 1 ; ; bq 0 for functions and for generalized functions that are equivalent to Lebesgue integrable functions in the neighborhood of the origin. R.U. Verma [1] gave an inversion formula for the transform
1
"
+1 2 (ai )1;p e;xt=2Gm;n G f (x) = p+1;q (xt) (bj )1;q 0
Z
#
f(t)dt;
(6.8.20)
provided that xcf(x) 2 L(R+ ). Kapoor and Masood [1] obtained the inversion formula for the generalized G-transform (6.1.1) of the form " # Z 1 a ; ; a ; 1 p m;n e Gf (x) = Gp;q a(xt) b ; ; b f(t)dt (6.8.21) 0 1 q
201
6.8. Bibliographical Remarks and Additional Information on Chapter 6
in terms of the Mellin transform and of another G-function. For Sections 6.3 and 6.4. The results presented in these sections were proved by the authors in Saigo and Kilbas [5]. Kapoor [1] introduced the G1 -transform (6.2.1) in the form # " Z 1 0; a ; ; a 1 p f(t) dt x +1 (6.8.22) G1f (x) = 0 Gm;n p+1;q t t b1 ; ; bq as a generalization of the Stieltjes transform, and proved its inversion formula in terms of the Mellin transform and of another G-function. In [3] Kapoor iterated this transform with the Laplace transform L in (2.5.2) to obtain generalizations of the third and fourth iterates of Laplace transforms and to establish some operational results. R.K. Saxena and N. Gupta [1] studied the asymptotic expansion of the transform G1
;; + ; + G1f (x) = G33;;13 xt 0; ; 0
Z
"
1
#
f(t) dt: t
(6.8.23)
Bhise [1] rst considered the modi ed Meijer G-transform of the form (6.2.3) with = 1 and = 0: For Sections 6.5{6.7.
1 + 1; ; m + m G1;0f (x) = x 0 xt f(t)dt (6.8.24) 1; ; m ; and proved its inversion formula. Further, Bhise studied properties of such a transform, namely, certain rules and recurrence relations [3], certain nite and in nite series [4] and composition relations [6]. Mittal [2] established two theorems involving H-functions for the G-transform which generalize the result given by Bhise [1], while K.C. Gupta and P.K. Mittal [3] developed a chain rule for the transform (6.8.24). Kapoor [2] obtained the relations of a more general transform
Z
1
+1;0 Gmm;m +1
G0;0f (x) = x
"
1
Z
0
Gm;n p;q
#
"
#
(ai )1;p xt f(t)dt (bj )1;q
(6.8.25)
than (6.8.24) with the Hankel transform H and the Y -transform given in (8.1.1) and (8.7.1), respectively. Using the Laplace transform L and its inverse L;1 , R.U. Verma [10] proved the inversion formula for the modi ed transform in (6.2.3)
G;;f (x) =
in the form
Z
0
1 x
t
"
a G21;;02 xt b; c
#
f(t)dt
f = M;b L;1Ma;b LMa;c L;1M;c; Gf;
(6.8.26) (6.8.27)
where the operator M is given by (3.3.11). A series of papers was devoted to investigating the integral transforms with the Meijer G-functions as kernels of the form (5.7.1) and (5.7.2) which generalize the Riemann{Liouville and Erdelyi{Kober type fractional integrals (2.7.1), (3.3.1) and (2.7.2), (3.3.2). Parashar [1] rst de ned such generalizations in the form # " Z x ; 1 ; + l; a ; ; a 1 p at m;n ; ; 1 t f(t)dt (6.8.28) G0+f (x) = x Gp+2;q+2 x ; 1 ; ; b1 ; ; bq 0
202
G-Transform and Modi ed G-Transforms on the Space L;r
Chapter 6.
and
G; f
(x) = x
1 m;n " ax ; 1 ; + l; a1; ; ap Gp+2;q+2 t ; 1 ; ; b1 ; ; bq x
Z
#
t;;1 f(t)dt
(6.8.29)
with a > 0 and investigated some properties of these transforms including their domains and ranges. Kalla [6] studied the operators
G;0+ f (x) = x;;1
x
Z
0
"
Gm;n p;q
and
G;;f
(x) = x
Z
1
x
# a ; ; a 1 p t t f(t)dt a x ; 1 ; ; b1 ; ; bq
(6.8.30)
# a ; ; a 1 p t t;;1 f(t)dt a x b1 ; ; bq
(6.8.31)
"
Gm;n p;q
with > 0 and complex and in the space Lr (R+ ) (r = 1) and proved their existence for Re() > 1=r ; 1 and Re() > ;1=r, respectively. Kalla [6] also proved the formulas for the Mellin transforms of these integrals for f(x) 2 Lr (R+ ) (1 5 r 5 2) and the relation of integration by parts 1
Z
0
1
Z
G;0+ f (x)g(x)dx =
0
f(x)
G;;g (x)dx
(6.8.32)
f 2 Lr (R+ ); g 2 Lr (R+ ); r1 + r10 = 1 ; provided that 2(m + n) > p + q and Re() > (r), where (r) is given by (3.3.9). Further, in [7] Kalla obtained inversion formulas for the integral transforms (6.8.30) and (6.8.31). Kiryakova [1], [2] introduced the modi ed G-transform of the form (5.7.12) and (5.7.13) in the form # " Z 1 ( + ) i i 1:m m;n m;n m; 0 f(xt1= )dt; (6.8.33) Ip;q f (x) Kp;q f (x) = G t 0 m;m ( j )1;m 0
and studied some of its properties in inversion formulas provided that f(x) is continuous on R+ or analytic in a starlike complex domain, considering an associated power weight (see also Kalla and Kiryakova [1] and Kiryakova [5] in this connection). Kiryakova, Raina and Saigo [1] expressed the ;1 operator Im;n p;q in terms of the Laplace transform L and its inverse L in the space Lr (R+ ) (r = 1). Luchko and Kiryakova [1] considered the modi ed G-transforms 1 f = p
Z
0
G
1
0 Gm; 0;2m
2 6 4
x
3
j + 1 ; 1
7 5
f(t)dt (x > 0)
(6.8.34)
1;2m
and G
1
2
x m;0 6 G 4 0 ; 2 m 0
2 f = p
Z
3
j + 1 ; 1
1;m
; (; j )1;m
(x > 0)
7 5
f(t)dt (6.8.35)
with > 0; > 0 and j 2 R (j = 1; ; 2m), proved the isomorphism of G1 and G2 in a special space, found the inversion relations, and established compositions of (6.8.34) and (6.8.35) with hyper-Bessel di erential operators. The results in Sections 6.5{6.7 have not been published before.
Chapter 7 HYPERGEOMETRIC TYPE INTEGRAL TRANSFORMS ON THE SPACE L;r 7.1. Laplace Type Transforms We consider the integral transform
L ;k f
(x) =
1
Z 0
(xt) e;(xt)k f (t)dt
(7.1.1)
with 2 C and k > 0. This is a modi cation of the generalized Laplace transform Lk; given in (3.3.3):
L ;k f
(x) = k; =k Wk;1=k L1=k;; f (x) = k; =k
L1=k;; f
k1=k x ;
(7.1.2)
where the operator W is de ned by (3.3.12). According to (7.1.2), (3.3.15) and (3.3.8) the Mellin transform (2.5.1) of (7.1.1) for a \suciently good" function f is given by the relation
+ s 1 1;0 1;0 (7.1.3) ML ;k f (s) = H0;1(s) Mf (1 ; s); H0;1(s) = ; k k for Re( + s) > 0: This relation shows that (7.1.1) is the H -transform (3.1.1) of the form 2
L ;k f
1 1;0 6 H0;1 4xt (x) = k1 Z
3
7 (7.1.4) 5 f (t)dt: 1
0 ; k k The constants a ; ; a1; a2; ; and in (1.1.7), (1.1.8), (1.1.11), (1.1.12), (3.4.1), (3.4.2) and (1.1.10) take the forms (7.1.5) a = k1 ; = k1 ; a1 = k1 ; a2 = 0; = ;Re( ); = 1; = k ; 21 : Let E1 be the exceptional set of the function H10;;01(s) in (7.1.3) given in De nition 3.4. Since the gamma function ;(z ) does not have zeros, then E1 is empty. From Theorems 3.6, 3.7 and 4.5, 4.7 we obtain the L;2 - and L;r -theory of the transform (7.1.1).
Theorem 7.1. Let 1 ; > ;Re( ): (i) There is a one-to-one transform L ;k 2 [L; ; L ;; ] such that (7:1:3) holds for Re(s) = 2
1 ; and f 2 L;2 .
203
1
2
204
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(ii) If f; g 2 L; ; then the relation 2
Z
1
0
f (x)
L ;k g
1 L ;k f (x)g (x)dx 0
Z
(x)dx =
(7.1.6)
holds for L ;k . (iii) Let f 2 L;2; 2 C and h > 0. When Re() > (1 ; )h ; 1; L ;k f is given by d L ;k f (x) = hx1;(+1)=h x(+1)=h dx 3 2 (;; h) Z 1 7 (7.1.7) H11;;21 64xt 1 5 f (t)dt: 0 ; ; ( ; ; 1 ; h ) k k When Re() < (1 ; )h ; 1; d L ;k f (x) = ;hx1;(+1)=h x(+1)=h dx 3 2 (;; h) Z 1 7 (7.1.8) H12;;20 64xt 5 f (t)dt: 1
0 ; (; ; 1; h); k k (iv) The transform L ;k is independent of in the sense that if 1 ; > ;Re( ) and 1 ; e > ;Re( ) and if the transforms L ;k and Le ;k on L;2 and Le ;2; respectively; are given in (7:1:3); then L ;k f = Le ;k f forf 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; L ;k f (x) is given in (7:1:1) and (7:1:4).
Theorem 7.2. Let 1 ; > ;Re( ) and 1 5 r 5 s 5 1. (a) The transform L ;k de ned on L; can be extended to L;r as an element of [L;r ; L ;;s ]. 2
If 1 5 r 5 2; then L ;k is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s0 with 1=s + 1=s0 = 1; then the relation (7:1:6) holds. (c) If 1 < r < 1; then there holds the representation L ;k (L;r ) = L1=k;; (L;r );
1
(7.1.9)
where the operator L; ;1=k is given in (3.3.3). Next we consider a further modi cation of the integral transform (7.1.1) in the form (5.1.3):
L ;k;; f
(x) = x
1
Z 0
(xt) e;(xt)k t f (t)dt
(7.1.10)
with ; ; 2 C and k > 0. For this transform the relations (7.1.3) and (7.1.6) take the forms (5.1.13) and (5.1.18): 1 + s + Mf (1 ; s ; + ) (7.1.11) ML ;k;; f (s) = ; k k and 1
Z
0
f (x)
L ;k;; g
(x)dx =
1 L ;k;; f (x)g (x)dx; 0
Z
(7.1.12)
205
7.1. Laplace Type Transforms
respectively. It follows from (7.1.11) that (7.1.10) is a kind of H ; -transform of the form
L ;k;; f
x
1
Z
2
H01;;10 64xt
3
(7.1.13)
+ ; 75 tf (t)dt: k k Theorems 5.25, 5.29 and 5.31 lead to the L;2 - and L;r -theory of the transform (7.1.10). ( x) = k
0
Theorem 7.3. Let 1 ; + Re() > ;Re( ): (i) There is a one-to-one transform L ;k ; 2 [L; ; L ; 2
;
1
;);2 ]
+Re(
such that (7:1:11)
holds for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation (7:1:12) holds for L ;k;;. (iii) Let 2 C ; h > 0 and f 2 L;2. When Re() > [1 ; + Re()]h ; 1; L ;k;;f is given by d L ;k;; f (x) = hx+1;(+1)=h x(+1)=h dx 3 2 (;; h) Z 1 7 (7.1.14) H11;;21 64xt + 5 t f (t)dt: 0 ; ; ( ; ; 1 ; h ) k k When Re() < [1 ; + Re()]h ; 1; d L ;k;; f (x) = ;hx+1;(+1)=h x(+1)=h dx 3 2 (;; h) Z 1 7 (7.1.15) H12;;20 64xt 5 t f (t)dt:
+ 0 ; (; ; 1; h); k k (iv) The transform L ;k;; is independent of in the sense that if 1 ; + > ;Re( ) and 1 ; e + > ;Re( ) and if the transforms L ;k;; and Le ;k;; on L;2 and Le ;2; respectively; are given in (7:1:11); then L ;k;; f = Le ;k;; f for f 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; (L ;k;;f )(x) is given in (7:1:10) and (7:1:13).
Theorem 7.4. Let 1 ; + Re() > ;Re( ) and 1 5 r 5 s 5 1. (a) The transform L ;k ; de ned on L; can be extended to L;r as an element of ;
2
[L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then L ;k is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If f 2 L;r and g 2 L+Re(;);s0 with 1=s +1=s0 = 1; then the relation (7:1:12) holds. (c) If 1 < r < 1; L ;k;; (L;r ) = L1=k;; ; (L ;Re(;);r ); (7.1.16) where the operators L1=k;; ; is given in (3.3.3). When = 0 and k = 1, (7.1.4) is the Laplace transform (2.5.2), and (7.1.3) and (7.1.4) take the forms MLf (s) = G10;;01(s) Mf (1 ; s); G10;;01(s) = ;(s) (7.1.17)
206
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
and
Lf
(x) =
Z
1
xt
;
#
f (t)dt; 0 respectively. Then from Theorems 6.1, 6.2, 6.6 and 6.8 we have 0
G
; ;
"
10 01
(7.1.18)
Corollary 7.4.1. Let < 1 and 1 5 r 5 s 5 1: (a) There is a one-to-one transform L 2 [L; ; L ;; ] such that the relation (7:1:17) holds 2
1
2
for Re(s) = 1 ; and f 2 L;2 . (b) Let 2 C and f 2 L;2. If Re() > ;; then Lf is given by
Lf (x) = x;
" # d x+1 Z 1 G1;1 xt ; f (t)dt; 1;2 dx 0 0; ; ; 1
(7.1.19)
while if Re() < ;;
Lf (x) = ;x;
(c)
" # d x+1 Z 1 G2;0 xt ; f (t)dt: 1;2 ; ; 1; 0 dx 0
(7.1.20)
is independent of in the sense that if < 1 and e < 1 and if the transforms L and L on L;2 and Le ;2 ; respectively; are given in (7:1:17); then Lf = Le f for f 2 L;2 \ Le ;2 . (d) For x > 0 and f 2 L;2; Lf is given in (2:5:2) and (7:1:18). (e) The Laplace transform L de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then L is a one-to-one transform from L;r onto L1;;s . (f) If f 2 L;r and g 2 L;s0 with 1=s + 1=s0 = 1; then L
e
1
Z 0
f (x) Lg (x)dx =
1
Z 0
Lf
(x)g (x)dx:
(7.1.21)
7.2. Meijer and Varma Integral Transforms
We consider the Meijer transform M k;m de ned by
M k;m f
(x) =
1
Z 0
(xt);k;1=2 e;xt=2 Wk+1=2;m(xt)f (t)dt
(7.2.1)
with k; m 2 R containing the Whittaker function Wl;m (z ) in the kernel. This function is given by 1 ; z= 2 m+1=2 (7.2.2) Wl;m (z) = e z m ; l + 2 ; 2m + 1; z ; where (a; c; x) is the con uent hypergeometric function of Tricomi: "
#
a ; (a; c; x) = ;(a);(a1; c + 1) G21;;12 xt 10;;1 ; c
(7.2.3)
207
7.2. Meijer and Varma Integral Transforms
which has the integral representation Z 1 e;xtta;1(1 + t)c;a;1 dt (Re(a) > 0) (7.2.4) (a; c; x) = ;(1a) 0 (see the formulas in Erdelyi, Magnus, Oberhettinger and Tricomi [1, 6.9(4) and 6.5(2)] and in Prudnikov, Brychkov and Marichev [3, 8.4.46.1]). When k = ;m; since (a; a + 1; z ) = z ;a from (7.2.4) and Wk+1=2;m (x) = x;m+1=2 e;x=2 by (7.2.2), we nd that the transform M ;m;m (7.2.1) coincides with the Laplace transform (2.5.2). By (3.3.11), (3.3.14) and the formula in Prudnikov, Brychkov and Marichev [3, 8.4.44.1] we have the following relation for the Mellin transform of M k;m f for a \suciently good" function f : MM k;m f (s) = G21;;02(s) Mf (1 ; s)
(7.2.5)
with
;(m ; k + s);(;m ; k + s) ; Re(s) > jmj + k: ;(;2k + s) By (7.2.6) M k;m is the G-transform (5.1.1) in the form G21;;02(s) =
M k;mf (x) =
;2k f (t)dt m ; k; ;m ; k
1 2;0 " G1;2 xt 0
Z
(7.2.6)
#
(7.2.7)
and the constants (6.1.5){(6.1.11) take the forms
a = = a1 = 1; a2 = 0; = k + jmj; = 1; = ; 21 ;
(7.2.8)
s 6= 2k ; i (i = 0; 1; 2; ) for Re(s) = 1 ; :
(7.2.9)
respectively. Let E2 be the exceptional set of the function G21;;02(s) in (7.2.6), which is the set of s 2 C of zero points of the function G21;;02(s) having zero only at the poles of the gamma function ;(;2k + s). Then, in accordance with De nition 6.1, 2= E2 means that From Theorems 6.1, 6.2 and 6.6, 6.8 we obtain the L;2 - and L;r -theory of the integral transform given in (7.2.1).
Theorem 7.5. Let = k + jmj and 1 ; > : (i) There is a one-to-one transform M k;m 2 [L;2; L1;;2] such that (7:2:5) holds for
Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation 1
Z
0
holds.
f (x) M k;mg (x)dx =
1
Z
0
M k;mf (x)g(x)dx
(7.2.10)
208
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(iii) Let f 2 L;2 and 2 C . If Re() > ;; then M k;m f is given by
M k;mf
(x) = x;
" # d x+1 Z 1 G2;1 xt ;; ;2k f (t)dt: m ; k; ;m ; k; ; ; 1 dx 0 2;3
(7.2.11)
When Re() < ;; " # Z 1 ;2k; ; d 3 ; 0 +1 M k;mf dx x 0 G2;3 xt ; ; 1; m ; k; ;m ; k f (t)dt: (7.2.12) (iv) The transform M k;m is independent of in the sense that if 1 ; > and 1 ; e > f and if the transforms M k;m and M k;m on L;2 and Le ;2 ; respectively; are given in (7:2:5); f then M k;m f = M k;m f for f 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; M k;m f (x) is given in (7:2:1) and (7:2:7).
(x) = ;x;
Theorem 7.6. Let = k + jmj and 1 ; > . (a) Let 1 5 r 5 s 5 1: The transform M k;m de ned on L;2 can be extended to L;r as
an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then M k;m is a one-to-one transform from L;r onto L1;;s . (b) Let 1 5 r 5 s 5 1: If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:2:10) holds. (c) Let 1 < r < 1 and the condition (7:2:9) holds. Then M k;m is one-to-one on L;r . (d) Let 1 < r < 1 and = 0. If (7:2:9) holds; then 0
M k;m (L;r ) = L(L;r );
(7.2.13)
; L1; (L;r ); M k;m(L;r ) = I;;1 ;;
(7.2.14)
where the Laplace operator L is given in (2:5:2): If (7:2:9) is not valid; then M k;m (L;r ) is a subset of the right-hand side of (7:2:13): (e) Let 1 < r < 1 and < 0. If (7:2:9) holds; then
; and L1; are given in (3:3:2) and (3:3:3): If (7:2:9) is not valid; where the operators I;;1 ;; then M k;m (L;r ) is a subset of the right-hand side of (7.2.14).
We also consider the Varma transform de ned by
V k;mf (x) =
1
Z
0
(xt)m;1=2e;xt=2 Wk;m (xt)f (t)dt:
(7.2.15)
According to (3.3.11) and (3.3.14) and Prudnikov, Brychkov and Marichev [3, 8.4.44.1], the Mellin transform (2.5.1) of (7.2.1) for a \suciently good" function f is given by the relation MV k;m f (s) = G21;;02(s) Mf (1 ; s)
(7.2.16)
;(2m + s);(s) ; ; m ; k + 21 + s
(7.2.17)
with G21;;02(s) =
Re(s) > ;m + jmj:
209
7.2. Meijer and Varma Integral Transforms
The relation (7.2.17) shows that (7.2.1) is the G-transform (5.1.1) of the form 3 2 1 Z 1 + m ; k 5 f (t)dt: V k;mf (x) = 0 G21;;02 4xt 2 2m; 0
(7.2.18)
When m + k = 1=2, from (7.2.2) and (7.2.4) we know W1=2;m;m = x1=2;m e;x=2 and we nd the transform V k;m in (7.2.15) coincides with the Laplace transform (2.5.2). The constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms
a = = a1 = 1; a2 = 0; = ;m + jmj; = 1; = m + k ; 1:
(7.2.19)
We note that if Re(s) = 1 ; ; then the condition (7.2.17) is equivalent to 1 ; > . Let E3 be the exceptional set of the function G21;;02(s) in (7.2.17). Since G21;;02(s) has zero only in the poles of the gamma function ;(m ; k + 1=2 + s); then in accordance with De nition 6.1 in Section 6.1 the condition 2= E3 means that (7.2.20) s 6= k ; m ; 12 ; i (i = 0; 1; 2; ) for Re(s) = 1 ; : Similarly to Theorems 7.5 and 7.6, we obtain the L;2 - and L;r -theory of the transform (7.1.1) from Theorems 6.1, 6.2 and 6.6, 6.8.
Theorem 7.7. Let = ;m + jmj and 1 ; > : (i) There is a one-to-one transform V k;m 2 [L;2; L1;;2] such that (7:2:16) holds for
Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation Z
0
1
f (x) V k;m g (x)dx =
1
Z
0
V k;mf (x)g(x)dx
(7.2.21)
holds.
(iii) Let f 2 L;2 and 2 C . If Re() > ;; then V k;mf is given by
V k;m f
2
1 2;1 d +1 ; 4 G2;3 xt (x) = x dx x 0 Z
;; m ; k + 21 2m; 0; ; ; 1
3 5
f (t)dt:
(7.2.22)
When Re() < ;; 2 1 ; ; 3 Z 1 d m ; k + 5 f (t)dt: V k;mf (x) = ;x; dx x+1 0 G32;;03 4xt 2 ; ; 1; 2m; 0
(7.2.23)
(iv) The transform V k;m is independent of in the sense that if 1 ; > and 1 ; > e
and if the transforms V k;m and V k;m on L;2 and Le ;2 ; respectively; are given in (7:2:16); then V k;m f = Vfk;m f for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; V k;mf (x) is given in (7:2:15) and (7:2:18). f
Theorem 7.8. Let = ;m + jmj and 1 ; > .
210
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(a) Let 1 5 r 5 s 5 1: The transform V k;m de ned on L;2 can be extended to L;r as
an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then V k;m is a one-to-one transform from L;r onto L1;;s . (b) Let 1 5 r 5 s 5 1: If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:2:21) holds. (c) Let 1 < r < 1. If the condition (7:2:20) holds; then V k;m is one-to-one on L;r . (d) Let 1 < r < 1 and jmj + k ; 1=2 = 0. If (7:2:20) holds; then 0
V k;m(L;r ) = L1;1=2;k;m(L;r );
(7.2.24)
where the operator L1;1=2;k;m is given in (3:3:3): If (7:2:20) is not valid; then V k;m (L;r ) is a subset of the right-hand side of (7:2:24): (e) Let 1 < r < 1 and jmj + k ; 1=2 < 0. If (7:2:20) holds; then ;jmj;k+1=2L V k;m(L;r ) = I;;1 1; (L;r ); ;;
(7.2.25)
;jmj;k+1=2 and L are given in (3:3:2) and (3:3:3): If (7:2:20) is not where the operators I;;1 1; ; ; valid; then V k;m (L;r ) is a subset of the right-hand side of (7.2.25).
In conclusion of this section we note that the relations (7.2.13), (7.2.14), (7.2.24) and (7.2.25) exhibit the ranges of the transforms M k;m and V k;m in (7.2.1) and (7.1.15) on the spaces L;r for any 1 < r < 1. They were obtained from the results in Section 6.1 for the G-transform (6.1.1). But such ranges of the G-transform can be estimated more precisely for certain integral transforms. For example, using the technique of the Mellin transform M and taking into acount the formulas (3.3.6){(3.3.8) and (3.3.14), we directly prove the following relations: f (s) = ;(; ; + s);(s) Mf (1 ; s + + ) (7.2.26) MLx I0+ ;(; + s) (Re(s ; ) = 1 ; + ) and
MI; x Lf (s) =
;( + + s);(s) Mf (1 ; s ; ; ) ;( + s) (Re(s + ) = 1 ; ; )
(7.2.27)
and I in (2.6.1) and (2.6.2) for the Riemann{Liouville fractional integration operators I0+ ; and the Laplace transform L in (2.5.2). On the other hand, by using (7.2.16) and (3.3.14) we have
MV k;m x + f (s) =
;(2m + s);(s) Mf (1 ; s + + ) ; m ; k + 21 + s
(Re(s ; ) = 1 ; + )
(7.2.28)
211
7.2. Meijer and Varma Integral Transforms
and MV k;m x; ; f (s) =
;(2m + s);(s) Mf (1 ; s ; ; ) ; m ; k + 21 + s
(7.2.29)
(Re(s + ) = 1 ; ; ):
(7.2.26) coincides with (7.2.28) when = 1=2 ; m ; k; = k ; m ; 1=2, and
1=2;m;k f (s) = MV x;2m f (s) (Re(s) = 1 ; ; 2m) MLxk;m;1=2 I0+ k;m
or 1=2;m;k x2m f (s) = MV f (s) (Re(s) = 1 ; ): MLxk;m;1=2 I0+ k;m
(7.2.30)
Similarly, (7.2.27) coincides with (7.2.29) when = m ; k + 1=2; = m + k ; 1=2, and MI;m;k+1=2 xm+k;1=2 Lf (s) = MV k;m x;2m f (s) (Re(s) = 1 ; ; 2m)
or
by
MI;m;k+1=2 xm+k;1=2 Lx2m f (s) = MV k;m f (s) (Re(s) = 1 ; ):
(7.2.31)
Motivated by the relations (7.2.30) and (7.2.31), we de ne the transforms V 1k;m and V 2k;m 1=2;m;k M V 1k;m = LMk;m;1=2I0+ 2m
(7.2.32)
V 2k;m = I;m;k+1=2Mm+k;1=2 LM2m:
(7.2.33)
and Applying the relations
f (x) = x I f (x); I0+ 0+;1;0
t f (x); L = L1;0 I; f (x) = I;;1 (7.2.34) ;0 connecting the Riemann{Liouville fractional integrals (2.7.1) and (2.7.2) with the Erdelyi{ Kober type integrals (3.3.1) and (3.3.2), and the Laplace transform (2.5.2) and the generalized Laplace transform (3.3.3), as well as (3.3.23) and (3.3.22), we can rewrite (7.2.32) and (7.2.33) as
1=2;m;k V 1k;m = LI0+:1 ;2m
(7.2.35)
m;k+1=2 L V 2k;m = I;;1 1;;2m ; ;0
(7.2.36)
and respectively. On the basis of (7.2.35) and (7.2.36) we obtain the following results from Theorem 3.2(a){ (c).
212
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
Theorem 7.9. Let 1 5 r 5 1 and < 1 + 2m. (a) If m + k < 1=2 and < 1; then for all s = r such that 1=s > 1=r + m + k ; 1=2; the
operator V 1k;m belongs to [L;r ; L1;;s ] and is a one-to-one transform from L;r onto L1;;s . For 1 5 r 5 2 and f 2 L;r ;(2m + s);(s) Mf (1 ; s) for Re(s) = 1 ; : (7.2.37) MV 1k;m f (s) = ; m ; k + 21 + s
(b) If m ; k > ;1=2 and > 0; then for all s = r such that 1=s > 1=r + k ; m ; 1=2; the
operator V 2k;m belongs to [L;r ; L1;;s ] and is a one-to-one transform from L;r onto L1;;s . For 1 5 r 5 2 and f 2 L;r ;(2m + s);(s) Mf (1 ; s) for Re(s) = 1 ; : (7.2.38) MV 2k;m f (s) = ; m ; k + 21 + s According to this theorem and (7.2.15){(7.2.17) the Varma transform can be interpreted by the transforms V 1k;m and V 2k;m as V k;m =V 1k;m and V k;m =V 2k;m for m + k < 1=2 and m ; k > ;1=2; respectively. Taking the same arguments as in Chapter 4, we obtain the range of the Varma transform.
Theorem 7.10. Let 1 < r < 1 and < 1 + 2m. (a) Let k + m < 1=2 and < 1. If (7:2:9) holds; then
1=2;m;k (L ): V k;m (L;r ) = LI0+:1 (7.2.39) ;r ;2m When (7:2:9) is not valid; then V k;m (L;r ) is a subset of the right-hand side of (7:2:39):
(b) Let m ; k > ;1=2 and > 0. If (7:2:9) holds; then
m;k+1=2 L V k;m (L;r ) = I;;1 (7.2.40) 1;;2m (L;r ): ;0 When (7:2:9) is not valid, then V k;m (L;r ) is a subset of the right-hand side of (7.2.40).
Remark 7.1. The relations (7.2.32) and (7.2.33) can be used to nd the inverse formulas
for the Varma transform V k;m in L;r -spaces.
7.3. Generalized Whittaker Transforms We consider the integral transform
W k; f (x) =
1
Z
0
(xt)k e;xt=2 W; (xt)f (t)dt
(7.3.1)
with ; 2 C and k 2 R; containing the Whittaker function (7.2.2) in the kernel. It is known that the Meijer transform (7.2.1) and the Varma transform (7.2.15) are particular cases of this generalized Whittaker transform W k; :
M k;m f (x) = W ;k+1k;1=2=;m2 f (x);
V k;mf (x) = W mk;m;1=2f (x):
(7.3.2)
213
7.3. Generalized Whittaker Transforms
Due to Prudnikov, Brychkov and Marichev [3, 8.4.44.1], the Mellin transform (2.5.1) of (7.3.1) for a \suciently good" function f is given by the relation
MW k; f (s) = G21;;02(s) Mf (1 ; s);
(7.3.3)
1 1 ; k+ + 2 +s ; k; + 2 +s ; G21;;02(s) = ;(k ; + 1 + s)
provided that Re(s) > jRe( )j ; k ; 21 :
(7.3.4)
The relation (7.3.3) shows that (7.3.1) is the G-transform (5.1.1) of the form
1;+k 2;0 6 k (7.3.5) W ; f (x) = 0 G1;2 4xt k + + 1 ; k ; + 1 75 f (t)dt: 2 2 The constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms 1 1 (7.3.6) a = = a1 = 1; a2 = 0; = jRe( )j ; k ; ; = 1; = k + % ; : 2 2 We note that for Re(s) = 1 ; the condition (7.3.4) is equivalent to 1 ; > . Lat E4 be the exceptional set of the function G21;;02(s) in (7.3.3). Since G21;;02(s) has a zero only at the poles of the gamma function ;(k ; + 1 + s); De nition 6.1 implies that the condition 2= E4 means that
Z
2
1
3
s 6= ; k ; 1 ; i (i = 0; 1; 2; ) for Re(s) = 1 ; :
(7.3.7)
From Theorems 6.1, 6.2 and 6.6, 6.8 we obtain the L;2 - and L;r -theory of the transform (7.3.1).
Theorem 7.11. Let = jRe( )j ; k ; 1=2 and 1 ; > : (i) There is a one-to-one transform W k; 2 [L; ; L ;; ] such that (7:3:3) holds for 2
Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation 1
Z 0
f (x)
W
k g ;
(x)dx =
Z 0
1
W k; f
1
2
(x)g (x)dx
(7.3.8)
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then W k; f is given by 2
W k; f
(x)
d +1 x = x; dx
Z 0
1
;; 1 + k ; f (t)dt: xt 1 1 k + + ; k ; + ; ; ; 1 2 2
2
G22;;13 64
3 7 5
(7.3.9)
214
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
When Re() < ;; W k; f (x) d +1 x = ;x; dx
1
Z
2
G32;;03 64xt
1 + k ; ; ;
3
7 (7.3.10) 5 f (t)dt: 1 1 ; ; 1; k + + 2 ; k ; + 2 (iv) Moreover; W k; is independent of in the sense that if 1 ; > and 1 ; e > k f and if the transforms W k; and W ; on L;2 and Le ;2 ; respectively; are given in (7:3:3); then k k W ; f = Wf ; f for f 2 L;2 \ Le;2. (v) For f 2 L;2 and x > 0; W k; f (x) is given in (7:3:1) and (7:3:5). 0
Theorem 7.12. Let = jRe( )j ; k ; 1=2 and 1 ; > . (a) Let 1 5 r 5 s 5 1: The transform W k; de ned on L; can be extended to L;r as
an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then W
L1;;s .
k ;
2
is a one-to-one transform from L;r onto
(b) Let 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1: Then the relation 0
(7:3:8) holds. (c) Let 1 < r < 1. If the condition (7:3:7) holds; then W k; is one-to-one on L;r . (d) Let 1 < r < 1 and Re() + jRe( )j ; 1=2 = 0. If (7:3:7) holds; then W k; (L;r ) = L1;;k;(L;r ); (7.3.11) where the operator L1;;k; is given in (3:3:3): If (7:3:7) is not valid; then W k; (L;r ) is a subset of the right-hand side of (7:3:11): (e) Let 1 < r < 1 and Re() + jRe( )j ; 1=2 < 0. If (7:3:7) holds; then W k; (L;r ) = I;;;1(;+; +k) L1; (L;r ); (7.3.12) where the operators I;;;1(;+; +k) and L1; are given in (3:3:1) and (3:3:3): If (7:3:7) is not valid; then W k; (L;r ) is a subset of the right-hand side of (7.3.12).
Remark 7.2. In view of (7.3.2), Theorems 7.5, 7.7 and 7.6, 7.8 in the previous section
are particular cases of Theorems 7.11 and 7.12.
Now we consider the modi cation of the transform (7.3.1) in the form (6.2.3):
W
k ; ;; f
(x) = x
1
Z
0
(xt)k e;xt=2 W; (xt)t f (t)dt
(7.3.13)
with ; ; ; 2 C and k 2 R. For this transform the relations (7.3.3), (7.3.5) and (7.3.8) take the forms, by consulting (6.2.13), (6.2.3) and (6.2.18): MW k; ;; f (s) = G21;;02 (s + ) Mf (1 ; s ; + ); (7.3.14) where G21;;02(s) is given in (7.3.3);
2
1 W k; ;;f (x) = x G21;;02 64xt
Z
0
1+k; 1 1 k + + ;k; + 2 2
3 7 5
t f (t)dt
(7.3.15)
215
7.3. Generalized Whittaker Transforms
and
1
Z
0
f (x)
W k; ;g
;
(x)dx =
Z
1
W k; ; f ;
0
(x)g (x)dx:
(7.3.16)
The exceptional set for this kernel G21;;02(s) is the same as E4 for (7.3.3). Then (7.3.7) shows that the condition ; Re() 2= E4 means that s 6= ; k ; 1 ; i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re():
(7.3.17)
From Theorems 6.38, 6.42 and 6.44 we have the L;2 - and L;r -theory of the transform (7.3.13).
Theorem 7.13. Let = jRe( )j ; k ; 1=2 and 1 ; + Re() > : (i) There is a one-to-one transform W k; ; 2 [L; ; L ; ; ; ] such that (7:3:14) 2
;
1
+Re(
)2
holds for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation (7:3:16) holds for W k; ;; . (iii) Let f 2 L;2 and 2 C . If Re() > ; + Re(); then W k; ;; f is given by
W k; ;f
;
(x) 2
d +1 1 2;1 6 ;; 1 + k ; x G2;3 4xt = x; dx 1 1 0 k + + ; k ; + ; ; ; 1 Z
2
When Re() < ; + Re();
W k; ;f
;
2
3 7 5
t f (t)dt:
(7.3.18)
(x)
1 + k ; ; ; d +1 7 (7.3.19) x G32;;03 64xt = ;x; dx 5 t f (t)dt: 1 1 0 ; ; 1; k + 2 ; k ; + 2 (iv) The transform W k; ;; is independent of in the sense that if 1 ; + > and k f 1 ; e + > and if the transforms W k; ;; and W ; ;; on L;2 and Le ;2; respectively; are k f given in (7:3:14); then W k; ;; f = W ; ;;f for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; W k; ;; f (x) is given in (7:3:13) and (7:3:15). Z
1
2
3
Theorem 7.14. Let = jRe( )j ; k ; 1=2 and 1 ; + Re() > . (a) If 1 5 r 5 s 5 1; then the transform W k; ; de ned on L; can be extended to L;r
as an element of [L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then W is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L+Re(;);s with 1=s + 1=s0 = 1; then the relation (7:3:16) holds. (c) If 1 < r < 1 and the condition (7:3:17) holds; then W k; ;; is one-to-one on L;r . (d) Let 1 < r < 1 and Re() + jRe( )j ; 1=2 = 0. If (7:3:17) holds; then ;
k ; ;;
2
0
W k; ; (L;r ) = L ;;k;; ;
1
L ;Re(;);r ;
(7.3.20)
216
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
where the operator L1;;k;; is given in (3:3:3): When (7:3:17) is not valid, W k; ;; (L;r ) is a subset of the right-hand side of (7:3:20): (e) Let 1 < r < 1 and Re() + jRe( )j ; 1=2 < 0. If (7:3:17) holds; then
W k; ;(L;r ) = I;; ;; k L ; ; L; ; ;r : (7.3.21) If (7:3:17) is not valid; then W k; ; (L;r ) is a subset of the right-hand side of (7.3.21).
;
( + + ) ;1
1
Re(
)
;
Remark 7.3. The results in Theorems 7.11 and 7.12 follow from those in Theorems 7.13
and 7.14 when = = 0:
7.4. D -Transforms We consider the integral transform
D f
(x) = 2; =2
1 ;xt=2 e D (2xt)1=2 f (t)dt
Z 0
(7.4.1)
with 2 C ; containing the parabolic cylinder function D (z ) de ned in terms of the con uent hypergeometric function of Tricomi (7.2.3) by D
(z ) = 2 =2e;z2 =4
; ; 1 ; z
2
2 2 2
!
(7.4.2)
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 8.2]). According to Prudnikov, Brychkov and Marichev [3, 8.4.18.1] the Mellin transform (7.4.1) for a \suciently good" function f is given by 1 ;(s); + s (7.4.3) MD f (s) = G21;;02(s) Mf (1 ; s); G21;;02 (s) = 1 ; 2 ; ; 2 +s provided that Re(s) > 0. This relation shows that (7.4.1) is the G-transform (6.1.1) of the form 3 2 1; Z 1 (7.4.4) D f (x) = 0 G21;;02 64xt 21 75 f (t)dt: 0; 2 The constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms
;1 (7.4.5) a = = a1 = 1; a2 = 0; = 0; = 1; = 2 : Let E5 be the exceptional set of the function G21;;02(s) in (7.4.3). Since G21;;02(s) has zero only at the poles of the gamma function ;(s + (1 ; )=2); De nition 6.1 implies that the condition 2= E5 means that
;1 (7.4.6) s 6= 2 ; i (i = 0; 1; 2; ) for Re(s) = 1 ; :
7.4.
D -Transforms
217
From Theorems 6.1, 6.2 and 6.6, 6.8 we obtain the L;2 - and L;r -theory of the transform (7.4.1).
Theorem 7.15. Let < 1: (i) There is a one-to-one transform D 2 [L; ; L ;; ] such that (7:4:3) holds for Re(s) = 2
1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation 1
Z 0
D g
f (x)
(x)dx =
1
2
D f
1
Z 0
(x)g (x)dx
(7.4.7)
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then D f is given by 2
D f
d +1 x (x) = x; dx
1
Z
0
2
G22;;13 4xt 6
;; 1 ;2 0; 12 ; ; ; 1
When Re() < ;;
D f
d +1 x (x) = ;x; dx
1
Z 0
2
G32;;03 6 4xt
1 ; ; ; 2 ; ; 1; 0; 21
3 7 5
f (t)dt:
(7.4.8)
3 7 5
f (t)dt:
(7.4.9)
(iv) The transform D is independent of in the sense that if < 1 and < 1 and if the e
f f transforms D and D on L;2 and Le ;2; respectively; are given in (7:4:3); then D f = D
for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; D f (x) is given in (7:4:1) and (7:4:4). f
Theorem 7.16. Let < 1 and 1 5 r 5 s 5 1: (a) The transform D de ned on L; can be extended to L;r as an element of [L;r ; L ;;s].
If 1 5 r 5 2; D is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:4:7) holds. (c) If 1 < r < 1 and the condition (7:4:6) holds; then D is one-to-one on L;r . (d) If 1 < r < 1; Re( ) = 0 and the condition (7:4:6) holds; then 2
1
0
D (L;r ) = L ;; = (L;r ); 1
2
(7.4.10)
where the operator L1;; =2 is given in (3:3:3): When (7:4:6) is not valid, D (L;r ) is a subset of the right-hand side of (7:4:10): (e) If 1 < r < 1; Re( ) < 0 and (7:4:6) holds; then
D (L;r ) =
; =2
I;;1;0 L
(L;r );
(7.4.11)
where the operators I;;;1 =;02 and L are given in (3:3:2) and (2:5:2): When (7:4:6) is not valid; D (L;r ) is a subset of the right-hand side of (7.4.11).
218
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
Now we consider a generalization of (7.4.1) in the form
D ;f
;
1 ;xt=2 e D (2xt)1=2 t f (t)dt
Z
(x) = 2; =2 x
0
(7.4.12)
with ; ; 2 C . In view of (6.2.8) and (7.4.4) this is a modi ed transform (6.2.3) of the form 3 2 1; Z 1 (7.4.13) D ;;f (x) = x 0 G21;;02 64xt 21 75 t f (t)dt: 0; 2 The Mellin transform (2.5.1) of (7.4.12) for a \suciently good" function f is given by MD ;; f (s) = G21;;02(s + ) Mf (1 ; s ; + );
(7.4.14)
where G21;;02(s) is the function in (7.4.3). For the exceptional set E5 of the function G21;;02(s) in (7.4.3), the condition ; Re() 2= EG means that
;1 (7.4.15) s 6= 2 ; i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re(): From Theorems 6.38, 6.42 and 6.44 we give the L;2 - and L;r -theory of the transform (7.4.12).
Theorem 7.17. Let ; Re() < 1: (i) There is a one-to-one transform D ; 2 [L; ; L ; ;
2
1
+Re(
for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation 1
Z 0
f (x)
D ;g ;
(x)dx =
Z
1
D ; f ;
0
;);2 ] such that (7:4:14) holds
(x)g (x)dx
(7.4.16)
holds.
(iii) Let f 2 L; and 2 C . If Re() > ; + Re(); then D ;f is given by 2
D ; f
;
d +1 x (x) = x; dx
;
1
Z 0
2
G22;;13 4xt 6
;; 1 ;2 0; 12 ; ; ; 1
When f 2 L;2 and Re() < ; + Re();
D ; f ;
d +1 x (x) = ;x; dx
1
Z 0
2
G32;;03 6 4xt
1 ; ; ; 2 ; ; 1; 0; 21
3 7 5
t f (t)dt:
(7.4.17)
3 7 5
t f (t)dt:
(7.4.18)
(iv) The transform D ; is independent of in the sense that if 1 ; + Re() > 0 and ;
f 1 ; e + Re() > 0 and if the transforms D ;; and D
;; on L;2 and Le ;2; respectively; are f given in (7:4:14); then D ;; f =D ;; f for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; D ;; f (x) is given in (7:4:12) and (7:4:13).
219
7.5. 1 F 1 -Transforms
Theorem 7.18. Let ; Re() < 1 and 1 5 r 5 s 5 1: (a) The transform D ; de ned on L; can be extended to L;r as an element of
[L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then D ;; is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If f 2 L;r and g 2 L+Re(;);s with 1=s +1=s0 = 1; then the relation (7:4:16) holds. (c) If 1 < r < 1 and the condition (7:4:15) holds; then D ;; is a one-to-one transform on L;r . (d) If 1 < r < 1; Re( ) = 0 and the condition (7:4:15) holds, then ;
2
0
D ; (L;r ) = L ;;; =
(7.4.19) where the operator L1;;; =2 is given in (3:3:3): If (7:4:15) is not valid, then D ;; (L;r ) is a subset of the right-hand side of (7:4:19): (e) If 1 < r < 1; Re( ) < 0 and (7:4:15) holds; then D ;; (L;r ) = I;;;1 =;2L1;; L;Re(;);r ; (7.4.20) ;
1
2
L ;Re(;);r ;
where the operators I;;;1 =;2 and L1;; are given in (3:3:2) and (3:3:3): If (7:4:15) is not valid; then D ;; (L;r ) is a subset of the right-hand side of (7.4.20).
7.5. F -Transforms 1
1
We now proceed to consider the integral transform ;(a) Z 1 (xt)k F (a; c; ;xt)f (t)dt k (7.5.1) 1 1 1 F 1 f (x) = ;(c) 0 with a; c 2 C (Re(a) > 0) and k 2 R containing the con uent hypergeometric or Kummer function 1F1 (a; c; z ) in the kernel (see (2.9.3) and (2.9.14)). The transform (7.5.1), rst considered by Erdelyi [3], is called the 1F1 -transform. According to Prudnikov, Brychkov and Marichev [3, 8.4.45.1], (3.3.11) and (3.3.14), the Mellin transform (2.5.1) of (7.5.1) for a \suciently good" function f is given by ;(k + s);(a ; k ; s) ; (7.5.2) M 1 F k1 f (s) = G11;;12(s) Mf (1 ; s); G11;;12(s) = ;(c ; k ; s) provided that 0 < Re(s + k) < Re(a). This relation shows that (7.5.1) is the G-transform (6.1.1) of the form " # Z 1 1;a+k 1 ; 1 k G1;2 xt f (t)dt: (7.5.3) 1 F 1 f (x) = 0 k; 1 ; c + k The constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms 1 (7.5.4) a = = a1 = 1; a2 = 0; = ;k; = Re(a ; k); = a ; c + k ; : 2 Let E6 be the exceptional set of the function G11;;12(s) in (7.5.2). It is composed of the poles of the gamma function ;(c ; k ; s); so De nition 6.1 implies the condition 2= E6 means that s 6= c ; k + i (i = 0; 1; 2; ) for Re(s) = 1 ; : (7.5.5)
220
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
From Theorems 6.1, 6.2 and 6.6, 6.8 we obtain the L;2 - and L;r -theory of the transform (7.5.1).
Theorem 7.19. Let ;Re(k) < 1 ; < Re(a ; k): (i) There is a one-to-one transform F k 2 [L; ; L ;; ] such that (7:5:2) holds for 1
Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation 1
Z 0
f (x)
1
F
1
k
g (x)dx =
1
2
1
Z
1
0
F
1
k
1
f (x)g (x)dx
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then F 2
1
F
1
k
1
"
dx
1
k
(7.5.6)
f is given by
;; 1 ; a + k f (t)dt: k; 1 ; c + k; ; ; 1
#
Z 1 d G12;;23 xt f (x) = x; x+1
2
0
(7.5.7)
When Re() < ;; Z 1 1 ; a + k; ; ; d +1 k x G22;;13 xt f (t)dt: 1 F 1 f (x) = ;x dx 0 ; ; 1; k; 1 ; c + k
"
#
(7.5.8)
(iv) The transform F k is independent of in the sense that if ;Re(k) < 1; < Re(a;k) 1
1
and ;Re(k) < 1 ; e < Re(a ; k) and if the transforms 1F 1 k and 1 Ff1k on L;2 and Le ;2 ; respectively; are given in (7:5:2);then 1 F1 k f = 1 Ff1 k f for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; 1F 1k f (x) is given in (7:5:1) and (7:5:3).
Theorem 7.20. Let ;Re(k) < 1 ; < Re(a ; k) and 1 5 r 5 s 5 1: (a) The transform F k de ned on L; can be extended to L;r as an element of
[L;r ; L1;;s ]. When 1 5 r 5 2; 1 F 1 is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:5:6) holds. (c) If 1 < r < 1 and the condition (7:5:5) holds; then 1F 1k is a one-to-one transform on L;r . (d) If 1 < r < 1; Re(a ; c) = 0 and the condition (7:5:5) holds; then 1
1
2
k
0
1
F
1
k
(L;r ) = L1;c;a;k (L;r );
(7.5.9)
where the operator L1;c;a;k is given in (3:3:3): When (7:5:5) is not valid; 1 F 1 k (L;r ) is a subset of the right-hand side of (7:5:9): (e) If 1 < r < 1; Re(a ; c) < 0 and (7:5:5) holds; then 1
F
1
k
(L;r ) = I;c;;1a;k L1;;k (L;r );
(7.5.10)
where the operators I;c;;1a;k and L1;;k are given in (3:3:2) and (3:3:3): When (7:5:5) is not valid; k 1 F 1 (L;r ) is a subset of the right-hand side of (7.5.10).
221
7.5. 1 F 1 -Transforms
Now we treat a generalization of (7.5.1) in the form ;(a) x Z 1 F (a; c; ;xt)tf (t)dt ; (7.5.11) F f ( x ) = 1 1 ;(c) 0 1 1 with a; c; ; 2 C (Re(a) > 0; c 6= 0; ;1; ;2; ). This is a modi ed transform (6.2.3) of the form " # Z 1 1;a 1;1 ; f (x) = x G1;2 xt t f (t)dt: (7.5.12) 1F 1 0 0; 1 ; c The Mellin transform (2.5.1) of (7.5.11) for a \suciently good" function f is given by ;(s);(a ; s) ; (7.5.13) M 1F 1 ; f (s) = G11;;12(s + ) Mf (1 ; s ; + ); G11;;12 (s) = ;(c ; s) provided that 0 < Re(s+ ) < Re(a). The constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms 1 (7.5.14) a = = a1 = 1; a2 = 0; = 0; = Re(a); = a ; c ; : 2 Let E7 be the exceptional set of the function G11;;12(s) in (7.5.12). Then similarly to (7.5.5) the condition ; Re() 2= E7 means that s 6= c + i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re():
(7.5.15)
Thus Theorems 6.38, 6.42 and 6.44 lead to the L;2 - and L;r -theory of the transform (7.5.11).
Theorem 7.21. Let 0 < 1 ; + Re() < Re(a): (i) There is a one-to-one transform F ; 2 [L; ; L ; 1
1
2
holds for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation 1
Z 0
f (x)
1
F
1
;
g (x)dx =
1
Z
1
0
F
1
;
1
+Re(
(iii) Let f 2 L; and 2 C . If Re() > ; + Re(); then F 1
F
1
;
1
;
f (x) = x
such that (7:5:13)
f (x)g (x)dx
holds.
2
;);2 ]
1
;
(7.5.16)
f is given by
d +1 Z 1 1;2 ;; 1 ; a x G2;3 xt t f (t)dt: dx 0 0; 1 ; c; ; ; 1 "
#
(7.5.17)
When Re() < ; + Re(); d +1 Z 1 2;1 1 ; a; ; ; ; x G2;3 xt f (x) = ;x 1F 1 dx 0 ; ; 1; 0; 1 ; c
"
(iv) The transform F
#
t f (t)dt:
(7.5.18)
is independent of in the sense that if 0 < ; 1; +Re() < Re(a) ; e and 0 < 1 ; e + Re() < Re(a) and if the transforms 1 F 1 and 1F 1 on L;2 and Le ;2 ; respectively; are given in (7:5:13); then 1 F 1 ; f = 1 Fe 1 ; f for f 2 L;2 \ Le ;2. 1
1
;
222
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(v) For f 2 L; and x > 0; F
2
1
1
;
f (x) is given in (7:5:11) and (7:5:12).
Let = = k 2 C . We have
Corollary 7.21.1. Let 0 < 1 ; + Re(k) < Re(a). (iii0) Let f 2 L; and 2 C . If Re() > ; + Re(k); then F 2
1
1
k
f is given by
d +1 Z 1 1;2 ;; 1 ; a k k ; x G2;3 xt tk f (t)dt: 1 F 1 f (x) = x dx 0 0; 1 ; c; ; ; 1
"
#
(7.5.19)
When Re() < ; + Re(k); 1
F
1
k
k;
f (x) = ;x
d +1 Z 1 2;1 1 ; a; ; x G2;3 xt tk f (t)dt: dx 0 ; ; 1; 0; 1 ; c
"
#
(7.5.20)
Theorem 7.22. Let 0 < 1 ; + Re() < Re(a) and 1 5 r 5 s 5 1: (a) The transform F ; de ned on L; can be extended to L;r as an element of
[L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then 1 F 1 is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If f 2 L;r and g 2 L+Re(;);s with 1=s +1=s0 = 1; then the relation (7:5:16) holds. (c) If 1 < r < 1 and the condition (7:5:15) holds; then 1F 1; is a one-to-one transform on L;r . (d) If 1 < r < 1; Re(a ; c) = 0 and the condition (7:5:15) holds; then 1
1
2
;
0
1
F
1
;
(L;r ) = L1;c;a; L ;Re(;);r ;
(7.5.21)
where the operator L1;c;a; is given in (3:3:3): When (7:5:15) is not valid; 1 F 1 ; (L;r ) is a subset of the right-hand side of (7:5:21): (e) If 1 < r < 1; Re(a ; c) < 0 and (7:5:15) holds; then 1
F
1
;
(L;r ) = I;c;;1a; L1;; L ;Re(;);r ;
(7.5.22)
where the operators I;c;;1a;k and L are given in (3:3:2) and (2:5:2): When (7:5:15) is not valid, ; 1 F1 (L;r ) is a subset of the right-hand side of (7.5.22).
Corollary 7.22.1. Let 0 < 1 ; + Re(k) < Re(a). (d0) If 1 < r < 1; Re(a ; c) = 0 and the condition (7:5:5) holds; then 1
F
1
k
(L;r ) = L1;c;a;k (L;r );
(7.5.23)
where the operator L1;c;a;k is given in (3:3:3): When (7:5:5) is not valid; 1 F 1 k (L;r ) is a subset of the right-hand side of (7:5:23): (e0) If 1 < r < 1; Re(a ; c) < 0 and (7:5:5) holds; then 1
F
1
k
(L;r ) = I;c;;1a;k L1;;k (L;r );
(7.5.24)
223
7.6. 1 F 2 -Transforms
where the operators I;c;;1a;k and L1;;k are given in (3:3:2) and (3:3:3): When (7:5:5) is not valid, k 1 F 1 (L;r ) is a subset of the right-hand side of (7.5.24).
Remark 7.4. When = = k; the transform F k in (7.5.13) coincides with the trans1
1
form 1 F 1k in (7.5.1). From Theorems 7.21 and 7.22 we obtain the statements (i), (ii), (iv), (v) of Theorem 7.19 and the statements (a), (b), (c) of Theorem 7.20, respectively. As for the statements given in Theorem 7.19(iii) and Theorem 7.20(d){(e), characterizing the representation and the range of the 1 F 1 k -transform (7.5.1), Corollaries 7.21.1 and 7.22.1 show that the latter in (7.5.23) and (7.5.24) are the same as in (7.5.9) and (7.5.10), while the former are changed. This is caused by the fact that these representations are valid for di erent conditions: the representations in (7.5.19) and (7.5.20) hold for Re() > ; + Re(k) and Re() < ; + Re(k); while those in (7.5.7) and (7.5.8) hold for Re() > ; and Re() < ;; respectively.
7.6. F -Transforms 1
2
We consider the integral transform ;( a) Z 1 (7.6.1) 1 F 2 f (x) = ;(c);(d) 0 1 F2 (a; c; d; ;xt)f (t)dt with a; c; d 2 C (Re(a) > 0) containing the hypergeometric function 1F2 (a; c; d; z ) in the kernel. According to Prudnikov, Brychkov and Marichev [3, 8.4.48.1] the Mellin transform (2.5.1) of (7.6.1) for a \suciently good" function f is given by ;(s);(a ; s) ; (7.6.2) M1 F 2 f (s) = G11;;13 (s) Mf (1 ; s); G11;;13(s) = ;(c ; s);(d ; s) provided that 0 < Re(s) < min[Re(a); 1=4 + Re(fc + d ; ag=2)]. This relation shows that (7.6.1) is the G-transform (6.1.1) of the form
1
F 2 f (x) =
Z
1 0
# 1;a xt f (t)dt: 0; 1 ; c; 1 ; d
"
G
1;1 1;3
(7.6.3)
The constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms a = 0; = 2; a1 = 1; a2 = ;1; = 0; = Re(a); = a ; c ; d:
(7.6.4)
Let E8 be the exceptional set of the function G11;;13(s) in (7.6.2). Then the condition 2= E8 means that s 6= c + i; s 6= d + j (i; j = 0; 1; 2; ) for Re(s) = 1 ; :
(7.6.5)
Thus from Theorems 6.1, 6.2 and 6.5 we have the L;2 - and L;r -theory of the transform (7.6.1).
Theorem 7.23. Let 0 < 1 ; < Re(a) and 2(1 ; ) + Re(a ; c ; d) 5 0:
224
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(i) There is a one-to-one transform F 2 [L; ; L ;; ] such that (7:6:2) holds for Re(s) = 1
2
2
1
2
1 ; and f 2 L;2 . If 2(1 ; ) + Re(a ; c ; d) = 0 and if the condition (7:6:5) holds, then the transform 1 F 2 maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then the relation Z
1
0
f (x) 1F 2 g (x)dx =
1
Z 0
1 F 2 f (x)g (x)dx
(7.6.6)
holds for 1 F2 . (iii) Let f 2 L;2 and 2 C . If Re() > ;; then 1F 2 f is given by " # Z 1 ;; 1 ; a d 1 ; 2 ; x+1 G2;4 xt f (t)dt: (7.6.7) 1 F 2 f (x) = x dx 0 0; 1 ; c; 1 ; d; ; ; 1 When Re() < ;; " # Z 1 1 ; a; ; d 2;1 +1 ; x G2;4 xt f (t)dt: (7.6.8) 1 F 2 f (x) = ;x dx 0 ; ; 1; 0; 1 ; c; 1 ; d (iv) The transform 1F 2 is independent of in the sense that if 0 < 1 ; < Re(a); 2(1 ; ) + Re(a ; c ; d) 5 0; 0 < 1 ; e < Re(a) and 2(1 ; e) + Re(a ; c ; d) 5 0; and if the transforms 1 F 2 and 1 Fe 2 on L;2 and Le ;2 ; respectively; are given in (7:6:2); then 1 F 2 f = 1 Fe 2 f for f 2 L;2 \ Le ;2 . (v) If 2(1 ; ) + Re(a ; c ; d) < 0; then for x > 0 and f 2 L;2; 1F 2 f (x) is given in (7:6:1) and (7:6:3).
Theorem 7.24. Let 0 < 1; < Re(a); 1 < r < 1 and 2(1; )+Re(a;c;d) 5 1=2; (r); where (r) is de ned in (3:3:9): (a) The transform 1F 2 de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; 2(1 ; ) ; Re(a ; c ; d)];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; the transform 1F 2 is one-to-one on L;r and there holds the equality (7:6:2) for f 2 L;r and Re(s) = 1 ; . (c) If f 2 L;r and g 2 L;s with 1 < s < 1; 1=r + 1=s = 1 and 2(1 ; ) + Re(a ; c ; d) 5 1=2 ; max[ (r); (s)]; then the relation (7:6:6) holds. (d) If the conditions in (7:6:5) hold; the transform 1F 2 is one-to-one on L;r and there holds the relation
F 2(L;r ) = M(a;c;d+1)=2 H2;c+d;a;1 L ;Re(a;c;d)=2;1=2;r ; (7.6.9) where M and H2; are given in (3:3:11) and (3:3:4): When (7:6:5) is not valid; then 1 F 2(L;r ) is a subset of the right-hand side of (7:6:9): (e) If f 2 L;r ; 2 C and 2(1 ; ) + Re(a ; c ; d) 5 1=2 ; (r); then 1F 2 f is given in (7:6:7) for Re() > ;; while in (7:6:8) for Re() < ; . If 2(1 ; ) + Re(a ; c ; d) < 0; 1 F 2 f is given in (7:6:1) and (7:6:3) for f 2 L;r . 1
Theorems 6.12 and 6.13 give the inversion formulas for the transform (7.6.1).
225
7.6. 1 F 2 -Transforms
Theorem 7.25. Let 0 < 1 ; < Re(a) and = max[1 ; Re(c); 1 ; Re(d)]. (a) If > ; 2(1 ; ) + Re(a ; c ; d) = 0 and f 2 L; ; then the inversion formula 0
0
2
;; a ; 1 c ; 1; d ; 1; 0; ; ; 1
"
Z 1 ; d +1 x G22;;14 xt f (x) = x
dx
0
#
1
F 2 f (t)dt
(7.6.10)
holds for Re() > ; 1 and Z 1 a ; 1; ; ; d +1 G32;;04 xt x f (x) = ;x "
dx
#
; ; 1; c ; 1; d ; 1; 0
0
1
F 2 f (t)dt
(7.6.11)
for Re() < ; 1. (b) Let 1 < r < 1; 0 < < Re(a;c;d)=2+5=4 and 2(1; )+Re(a;c;d) 5 1=2; (r); where (r) is given in (3:3:9). If f 2 L;r ; then the inversion formulas (7:6:10) and (7:6:11) hold for Re() > ; 1 and for Re() < ; 1; respectively. Now we consider a modi cation of (7.6.1) in the form ;( a) Z 1 ; (7.6.12) f (x) = 1F 2 ;(c);(d) x 0 1 F2 (a; c; d; ;xt)t f (t)dt with a; c; d; ; 2 C (Re(a) > 0). From (7.6.2) and (3.3.14) the Mellin transform of (7.6.12) for a \suciently good" function f is given by
M 1 F 2 ; f (s) = G11;;13(s + ) Mf (1 ; s ; + )
(7.6.13)
for 0 < Re(s + ) < Re(a); Re(s + ) < 1=4 + Re(c + d ; a)=2; c; d 6= 0; ;1; ;2; and G11;;13(s) in (7.6.2). Hence the transform (7.6.12) is a modi ed transform (6.2.3) of the form 1
1
Z
F 2 f (x) = x ;
0
"
G
1;1 1;3
# 1;a xt t f (t)dt: 0; 1 ; c; 1 ; d
(7.6.14)
If E8 is the exceptional set of the function G11;;13(s) in (7.6.2), then the condition 2= E8 means that s 6= c + i; s 6= d + j (i; j = 0; 1; 2; ) for Re(s) = 1 ; + Re():
(7.6.15)
From Theorems 6.38 and 6.41 we obtain the L;2 - and L;r -theory of the 1 F2 ; -transform (7.6.12).
Theorem 7.26. Let 0 < 1 ; + Re() < Re(a) and 2[1 ; + Re()] + Re(a ; c ; d) 5 0: (i) There is a one-to-one transform F ; 2 [L; ; L ;; ] such that (7:6:13) holds for 1
2
2
1
2
Re(s) = 1 ; + Re( ; ) and f 2 L;2 . If 2[1 ; + Re()] + Re(a ; c ; d) = 0 and if the condition (7:6:15) holds; then the transform 1 F 2; maps L;2 onto L1; +Re(;);2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation 1
Z 0
f (x) 1 F 2
;
g (x)dx =
1
Z 0
g (x) 1 F 2 ; f (x)dx
(7.6.16)
226
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
holds.
(iii) Let 2 C and f 2 L; . If Re() > ; + Re(); then F 2
1
2
;
f is given by
1
F 2 ; f (x) Z 1 ;; 1 ; a ; d +1 G12;;24 xt t f (t)dt: = x dx x 0 0; 1 ; c; 1 ; d; ; ; 1 "
#
(7.6.17)
When Re() < ; + Re();
1
F 2 ; f (x) "
Z 1 = ;x ; d x+1 G22;;14 xt
dx
(iv) The transform F
0
# 1 ; a; ; t f (t)dt: ; ; 1; 0; 1 ; c; 1 ; d
(7.6.18)
is independent of in the sense that if 0 < 1 ; + Re() < Re(a); 2[1 ; +Re()]+Re(a ; c ; d) 5 0 and 0 < 1 ; e +Re( ) < Re(a) and 2[1 ; e +Re()]+ ; ; e Re(a ; c ; d) 5 0: and if the transforms 1 F 2 and 1F 2 on L;2 and Le ;2 ; respectively; are given in (7:6:13); then 1F 2 ; f = 1 Fe 2; f for f 2 L;2 \ Le ;2 . (v) If 2[1 ; + Re()] + Re(a ; c ; d) < 0; then for f 2 L;2 and x > 0; 1F 2; f (x) is given in (7:6:12) and (7:6:14). 1
2
;
Theorem 7.27. Let 0 < 1 ; + Re() < Re(a); 1 < r < 1 and 2[1 ; + Re()] +
Re(a ; c ; d) 5 1=2 ; (r); where (r) is de ned in (3:3:9): (a) The transform 1F 2; de ned on L;2 can be extended to L;r as an element of [L;r ; L1; +Re(;);s ] for all s with r 5 s < 1 such that s0 = [1=2 ; 2f1 ; +Re()g; Re(a ; c ; d)];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; the transform 1F 2; is one-to-one on L;r and there holds the equality (7:6:13) for f 2 L;r and Re(s) = 1 ; + Re( ; ). (c) If f 2 L;r and g 2 L+Re(;);s with 1 < s < 1; 1=r +1=s = 1 and 2[1 ; +Re()]+ Re(a ; c ; d) 5 1=2 ; max[ (r); (s)]; then the relation (7:6:16) holds. (d) If the conditions in (7:6:15) hold; then the transform 1F 2; is one-to-one on L;r and there holds the relation
1
F 2 ; (L;r ) = M+(a;c;d+1)=2 H 2;c+d;a;1 L ;Re(a;c;d+1)=2;Re();r ;
(7.6.19)
where M and H 2; are given in (3:3:11) and (3:3:4): When (7:6:15) is not valid; then ; (L;r ) is a subset of the right-hand side of (7:6:19): 1F 2 (e) If f 2 L;r with 1 < r < 1; 2 C and 2[1 ; + Re()] + Re(a ; c ; d) 5 1=2 ; (r); then 1 F2 ; f is given in (7:6:17) for Re() > ; + Re(); while 1 F 2 ; f is given in (7:6:18) for Re() < ; + Re(). If 2[1 ; + Re()] + Re(a ; c ; d) < 0; 1 F 2; f is given in (7.6.12). From Theorems 6.48 and 6.49 we have the inversion formulas for the transform (7.6.12).
Theorem 7.28. Let 0 < 1 ; + Re() < Re(a) and = max[1 ; Re(c); 1 ; Re(d)]. 0
227
7.7. 2 F 1 -Transforms
(a) If > ; 2[1 ; + Re()] + Re(a ; c ; d) = 0 and f 2 L; ; then the inversion
formulas
0
2
f (x) = x;;
d +1 x dx
1
Z 0
G
; ;
"
21 24
;; a ; 1 xt t; F c ; 1; d ; 1; 0; ; ; 1
#
(t)dt
(7.6.20)
a ; 1; ; xt t; 1 F 2 ; f (t)dt ; ; 1; c ; 1; d ; 1; 0
(7.6.21)
1
2
; f
hold for Re() > ; Re() ; 1 and f (x) = ;x;;
1
Z 0
d +1 x dx
G
; ;
30 24
"
#
for Re() < ; Re() ; 1. (b) Let 1 < r < 1; 0 < ; Re() < Re(a ; c ; d)=2+5=4 and 2[1 ; +Re()]+Re(a ; c ; d) 5 1=2 ; (r); where (r) is given in (3:3:9). If f 2 L;r ; then the relations (7:6:20) and (7:6:21) hold for Re() > ; Re() ; 1 and for Re() < ; Re() ; 1; respectively.
7.7. F -Transforms 2
1
Let us consider the integral transforms ;(a);(b) Z 1 F (a; b; c; ;xt)f (t)dt (7.7.1) F f ( x ) = 2 1 ;(c) 0 2 1 and 1 ;( a);(b) Z 1 (7.7.2) 2 F 1 f (x) = ;(c) 0 2F1 a; b; c; ; xt f (t)dt with a; b; c 2 C (Re(a) > 0; Re(b) > 0) involving the Gauss hypergeometric function 2 F1 (a; b; c; z ) in the kernels. According to Prudnikov, Brychkov and Marichev [3, 8.4.49.13 and 8.4.49.14] the Mellin transforms of (7.7.1) and (7.7.2) for a \suciently good" function f are given by ;(s);(a ; s);(b ; s) (7.7.3) M 2 F 1 f (s) = G12;;22(s) Mf (1 ; s); G12;;22(s) = ;(c ; s) and ;(;s);(a + s);(b + s) (7.7.4) M 2F 1 f (s) = G22;;12(s) Mf (1 ; s); G22;;12 (s) = ;(c + s) under the restrictions 0 < Re(s) < min[Re(a); Re(b)] and ; min[Re(a); Re(b)] < Re(s) < 0, respectively. These relations show that (7.7.1) and (7.7.2) are G-transforms (6.1.1) of the form " # Z 1 1 ; a; 1 ; b 1;2 G2;2 xt f (t)dt (7.7.5) 2 F 1 f (x) = 0 0; 1 ; c
228
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
and
2 F 1 f (x) =
1
Z 0
G
1; c
"
; ;
xt
21 22
#
f (t)dt:
a; b
(7.7.6)
The constants a; ; a1; a2; ; and in (6.1.5){(6.1.11) have the forms
and
a = 2; = 0; a1 = 1; a2 = 1; = 0; = min[Re(a); Re(b)]; = a + b ; c ; 1
(7.7.7)
a = 2; = 0; a1 = 1; a2 = 1; = ; min[Re(a); Re(b)]; = 0; = a + b ; c ; 1:
(7.7.8)
Let E9 and E10 be the exceptional sets of the functions G12;;22(s) and G22;;12 (s) in (7.7.3) and (7.7.4). Due to De nition 6.1 the conditions 2= E9 and 2= E10 mean that s 6= c + i (i = 0; 1; 2; ) for Re(s) = 1 ;
(7.7.9)
s 6= ;c ; i (i = 0; 1; 2; ) for Re(s) = 1 ; ;
(7.7.10)
and respectively. Theorems 6.1 and 6.2 deduce the following L;2 -theory of the transforms 2 F 1 and 2 F 1 .
Theorem 7.29. Let 0 < 1 ; < min[Re(a); Re(b)]: (i) There is a one-to-one transform F 2 [L; ; L ;; ] such that (7:7:3) holds for Re(s) = 2
1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation 1
Z 0
1
f (x) 2 F 1g (x)dx =
2
1
1
Z 0
2
2
F 1 f (x)g (x)dx
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then F 2
2
"
dx
f is given by
;; 1 ; a; 1 ; b f (t)dt: 0; 1 ; c; ; ; 1
(7.7.12)
1 ; a; 1 ; b; ; # f (t)dt: ; ; 1; 0; 1 ; c
(7.7.13)
#
d +1 Z 1 1;3 ; x G3;3 xt 2 F 1 f (x) = x
1
(7.7.11)
0
When Re() < ;;
" d +1 Z 1 2;2 ; G3;3 xt x 2 F 1 f (x) = ;x
dx
0
(iv) The transform F is independent of in the sense that if 0 < 1 ; < min[Re(a); 2
1
Re(b)] and 0 < 1 ; e < min[Re(a); Re(b)] and if the transforms 2 F 1 and 2 Fe 1 on L;2 and Le ;2 ; respectively; are given in (7:7:3); then 2 F 1 f = 2Fe 1 f for f 2 L;2 \ Le ;2.
229
7.7. 2 F 1 -Transforms
(v) For f 2 L; and x > 0; F 2
2
1 f (x) is given in (7:7:1) and (7:7:5).
Theorem 7.30. Let ; min[Re(a); Re(b)] < 1 ; < 0: (i) There is a one-to-one transform F 2 [L; ; L ;; ] such that (7:7:4) holds for 2
Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation 1
Z 0
f (x) 2 F 1 g (x)dx =
1
2
1
Z
2
2
0
1
F 1 f (x)g (x)dx
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then F 2
2
f
is given by
;; 1; c f (t)dt: a; b; ; ; 1
" d +1 Z 1 2;2 ; x G3;3 xt 2 F 1 f (x) = x dx 0
1
(7.7.14)
#
(7.7.15)
When Re() < ;;
d +1 Z 1 3;1 1; c; ; ; x G3;3 xt 2 F 1 f (x) = ;x
"
dx
#
; ; 1; a; b
0
f (t)dt:
(7.7.16)
(iv) The transform F is independent of in the sense that if ; min[Re(a);Re(b)] < 2
1
e 1 ; < 0 and ; min[Re(a); Re(b)] < 1 ; e < 0 and if the transforms 2 F 1 and 2 F 1 on L;2 e and Le ;2 ; respectively; are given in (7:7:4); then 2 F 1 f = 2 F 1 f for f 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; 2F 1 f (x) is given in (7:7:2) and (7:7:6).
From Theorems 6.6 and 6.7 we obtain the L;r -theory of the transforms 2 F 1 and 2F 1 .
Theorem 7.31. Let = min[Re(a); Re(b)], 0 < 1 ; < and ! = a + b ; c ; . (a) If 1 5 r 5 s 5 1; then the transform F de ned on L; can be extended to L;r as 2
1
2
an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then 2 F 1 is a one-to-one transform from L;r onto L;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:7:11) holds. (c) If 1 < r < 1 and the condition (7:7:9) holds; then 2F 1 is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:7:9) holds; then 0
2
F 1 (L;r ) =
LL1;1+c;a;b
(L1;;r );
(7.7.17)
where L and L1;1+c;a;b are given in (2:5:2) and (3:3:3): If (7:7:9) is not valid; then 2 F 1(L;r ) is a subset of the right-hand side of (7:7:17): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:7:9) holds; then
2
F 1(L;r ) = I;;;1! ;0LL1;1; (L1;;r );
(7.7.18)
where I;;;1! ;0 is given in (3:3:2). If (7:7:9) is not valid; then 2F 1 (L;r ) is a subset of the righthand side of (7.7.18).
230
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
Theorem 7.32. Let = ; min[Re(a); Re(b)] , < 1 ; < 0 and ! = a + b ; c + . (a) If 1 5 r 5 s 5 1; then the transform F de ned on L; can be extended to L;r 2
1
2
2F 1
as an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then is a one-to-one transform from L;r onto L1;;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:7:14) holds. (c) If 1 < r < 1 and the condition (7:7:10) holds; then 2F 1 is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:7:10) holds; then 0
2
F 1 (L;r ) =
L1; L1;1;!
(L1;;r );
(7.7.19)
where L1; is given in (3:3:3): If (7:7:10) is not valid; then 2F 1 (L;r ) is a subset of the right-hand side of (7:7:19): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:7:10) holds; then 2
F 1 (L;r ) = I;;;1! ;; L1; L1;1 (L1;;r );
(7.7.20)
where I;;;1! ;; is given in (3:3:2). If (7:7:10) is not valid; then 2 F 1 (L;r ) is a subset of the right-hand side of (7.7.20). Now we treat generalizations of (7.7.1) and (7.7.2) in the forms Z 1 ; f (x) = ;(a);(b) x (7.7.21) F 2 F1 (a; b; c; ;xt)t f (t)dt 2 1 ;(c) 0 and 1 ;( a);(b) Z 1 ;; (7.7.22) f (x) = 2F 1 ;(c) x 0 2 F1 a; b; c; ; xt t f (t)dt with a; b; c; ; 2 C (Re(a) > 0; Re(b) > 0). By virtue of (7.7.3), (7.7.4) and (3.3.14) the Mellin transforms of (7.7.21) and (7.7.22) for a \suciently good" function f are given by
(7.7.23)
(7.7.24)
M 2 F 1 ; f (s) = G12;;22(s + ) Mf (1 ; s ; + )
and
M 2 F 1 ;; f (s) = G22;;12(s + ) Mf (1 ; s ; + );
where G12;;22(s) and G22;;12(s) are de ned in (7.7.3) and (7.7.4). Thus the transforms (7.7.21) and (7.7.22) are modi ed transforms (6.2.3) of the forms 2
F1
; f
(x) = x
Z
1 0
G
; ;
Z
1
12 22
"
1 ; a; 1 ; b # xt t f (t)dt 0; 1 ; c
(7.7.25)
and
2
F 1 ;; f (x) = x
0
G
; ;
21 22
"
xt
1; c a; b
#
t f (t)dt;
(7.7.26)
231
7.7. 2 F 1 -Transforms
respectively. For the exceptional sets E9 and E10 of the functions G12;;22(s) and G22;;12(s) in (7.7.3) and (7.7.4), ; Re() 2= E9 and ; Re() 2= E10 mean that s 6= c + i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re()
(7.7.27)
s 6= ;c ; i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re():
(7.7.28)
and Theorem 6.38 yields the L;2 -theory of the transforms 2 F 1 ; and 2 F 1 ;; .
Theorem 7.33. Let 0 < 1 ; + Re() < min[Re(a); Re(b)]: (i) There is a one-to-one transform F ; 2 [L; ; L ; 2
1
2
holds for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation 1
Z 0
f (x) 2 F 1 ; g (x)dx =
1
Z
1
;);2 ]
+Re(
; f (x)g (x)dx 2F 1
0
holds.
(iii) Let f 2 L; and 2 C . If Re() > ; + Re(); then F 2
2
F1
; f
2
(x) = x;
such that (7:7:23)
1
(7.7.29)
; f
is given by
d +1 Z 1 1;3 ;; 1 ; a; 1 ; b x G3;3 xt t f (t)dt: dx 0 0; 1 ; c; ; ; 1
"
#
(7.7.30)
When Re() < ; + Re(); 2
F1
; f
(x) = ;x;
(iv) The transform F
d +1 Z 1 2;2 1 ; a; 1 ; b; ; x G3;3 xt t f (t)dt: dx 0 ; ; 1; 0; 1 ; c
"
#
(7.7.31)
is independent of in the sense that if 0 < 1 ; ; < ; and F e min[Re(a); Re(b)] and 0 < 1 ; e < min[Re(a); Re(b)] and if the transforms F 2 1 2 1 on L;2 and Le ;2; respectively; are given in (7:7:23); then 2 F 1; f = 2 Fe 1; f for f 2 L;2 \Le ;2 . (v) For f 2 L;2 and x > 0; 2F 1; f (x) is given in (7:7:21) and (7:7:25). 2
1
;
Theorem 7.34. Let ; min[Re(a); Re(b)] < 1 ; + Re() < 0: (i) There is a one-to-one transform F ; 2 [L; ; L ; ; ; ] such that (7:7:24) 2
1
;
2
holds for Re(s) = 1 ; + Re( ; ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L+Re(;);2; then the relation Z 0
1
f (x) 2F 1 ;; g (x)dx =
1
Z
0
2
1
+Re(
)2
F 1 ;; f (x)g (x)dx
holds.
(iii) Let f 2 L; and 2 C . If Re() > ; + Re(); then F 2
2
1
;; f
(7.7.32) is given by
d +1 Z 1 2;2 ;; 1; c ;; ; x G3;3 xt t f (t)dt: f (x) = x 2F 1 dx 0 a; b; ; ; 1
"
#
(7.7.33)
232
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
When Re() < ; + Re(); " d +1 Z 1 3;1 1; c; ; ; ;; x G3;3 xt f (x) = ;x 2F 1 dx 0
#
; ; 1; a; b
(iv) The transform F
t f (t)dt:
(7.7.34)
;; is independent of in the sense that if ; min[Re(a); Re(b)] < 1 ; < 0 and ; min[Re(a); Re(b)] < 1 ; e < 0 and if the transforms 2F;;1 ;; and 2 Fe 1 ;; on L;2 and Le ;2; respectively; are given in (7:7:24) ; then 2 F 1 ;; f = 2Fe 1 f for f 2 L;2 \Le ;2 . ;; (v) For f 2 L;2 and x > 0; 2F 1 f (x) is given in (7:7:22) and (7:7:26). 2
1
Theorems 6.42 and 6.43 produce the L;r -theory of the transforms 2F 1 ; and 2 F 1 ;; .
Theorem 7.35. Let = min[Re(a); Re(b)]; 0 < 1 ; + Re() < and ! = a + b ; c ; . (a) If 1 5 r 5 s 5 1; then the transform F ; de ned on L; can be extended to L;r 2
1
2
as an element of [L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then 2 F 1 is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L+Re(;);s with 1=s + 1=s0 = 1; then the relation (7:7:29) holds. (c) If 1 < r < 1 and the condition (7:7:27) holds; then the transform 2F 1; is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:7:27) holds; then ;
0
2
F 1 ; (L;r ) =
L1;; L1;1+c;a;b+
(L1; +Re(;);r );
(7.7.35)
where L1;; and L1;1+c;a;b are given in (3:3:3): If (7:7:27) is not valid; then 2 F 1 ; (L;r ) is a subset of the right-hand side of (7:7:35): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:7:27) holds; then ; (L ) = I ;! L F L 2 1 ;r ;;1; 1;; 1;1; + (L1; +Re(;);r );
(7.7.36)
where I;;;1! ; is given in (3:3:2). If (7:7:27) is not valid; then 2 F 1; L;r ) is a subset of the right-hand side of (7.7.36).
Theorem 7.36. Let = ; min[Re(a); Re(b)]; < 1 ; +Re() < 0 and ! = a + b ; c + . (a) If 1 5 r 5 s 5 1; then the transform F ; de ned on L; can be extended to L;r 2
1
;
;; 2F 1
2
as an element of [L;r ; L1; +Re(;);s ]. If 1 5 r 5 2; then is a one-to-one transform from L;r onto L1; +Re(;);s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L+Re(;);s with 1=s + 1=s0 = 1; then the relation (7:7:32) holds. (c) If 1 < r < 1 and the condition (7:7:28) holds; then the transform 2F 1;; is one-toone on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:7:28) holds; then 0
;; (L;r ) = 2F 1
L1; ; L1;1+;!
(L1; +Re(;);r );
(7.7.37)
where L1; ; and L1;1+;! are given in (3:3:3): If (7:7:28) is not valid; then 2F 1 ;; (L;r ) is a subset of the right-hand side of (7:7:37):
233
7.8. Modi ed 2 F 1 -Transforms
(e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:7:28) holds; then
2
F 1 ;; (L;r ) = I;;;1! ;; L1; ; L1;1+ (L1; +Re(;);r );
(7.7.38)
where I;;;1! ;; is given in (3:3:2). If (7:7:28) is not valid; then 2 F 1 ;; (L;r ) is a subset of the right-hand side of (7.7.38).
7.8. Modi ed F -Transforms 2
1
Let us study the transforms x f (t) ;( a);(b) Z 1 2 F 1 f (x) = ;(c) 0 2 F1 a; b; c; ; t t dt
1
(7.8.1)
and
t f (t) ;( a);(b) Z 1 (7.8.2) 2 F 1 f (x) = ;(c) 0 2 F1 a; b; c; ; x x dt with a; b; c 2 C (Re(a) > 0; Re(b) > 0) which are modi cations of the transforms (7.7.1) and (7.7.2) in the forms (6.2.1) and (6.2.2). Comparing with (6.2.11) and (6.2.12), we nd that the Mellin transforms of (7.8.1) and (7.8.2) have the forms
2
M 2 F 11 f (s) = G12;;22(s) Mf (s)
(7.8.3)
and
M 2 F 1 2 f (s) = G12;;22(1 ; s) Mf (s);
(7.8.4)
where G12;;22(s) is given in (7.7.3). These relations show that (7.8.1) and (7.8.2) can be regarded as the modi ed G-transforms (6.2.1) and (6.2.2) in the forms # " Z 1 1 ; a; 1 ; b f (t) 1;2 x 1 dt (7.8.5) G2;2 2 F 1 f (x) = t t 0 0; 1 ; c and # " Z 1 t 1 ; a; 1 ; b f (t) 1;2 2 dt: (7.8.6) G2;2 2 F 1 f (x) = x 0; 1 ; c x 0 Now we can apply the results in Sections 6.3 and 6.4 to obtain the L;2 - and L;r -theory of the transforms (7.8.1) and (7.8.2) if we take into account that by (7.7.9) the conditions 1 ; 2= E9 and 2= E9 for the exceptional set E9 of the function G12;;22(s) in (7.7.3) are equivalent to s 6= c + i (i = 0; 1; 2; ) for Re(s) =
(7.8.7)
s 6= c + i (i = 0; 1; 2; ) for Re(s) = 1 ; ;
(7.8.8)
and
234
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
respectively. From Theorems 6.14 and 6.26 we obtain the L;2 -theory of the transforms (7.8.1) and (7.8.2).
Theorem 7.37. Let 0 < < min[Re(a); Re(b)]: (i) There is a one-to-one transform F 2 [L; ] such that (7:8:3) holds for Re(s) = 2
1
1
and f 2 L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation 1
Z 0
holds.
f (x) 2 F 1 g (x)dx = 1
1
Z
2
0
2
F 1 2 f (x)g (x)dx
(iii) Let f 2 L; and 2 C . If Re() > ; 1; then F 2
2
F1
1
2
1
1
f is given by
" d +1 Z 1 1;3 x ;; 1 ; a; 1 ; b ; x G3;3 f (x) = x dx t 0; 1 ; c; ; ; 1 0
(7.8.9)
#
f (t) dt: t
(7.8.10)
When Re() < ; 1;
1 ; a; 1 ; b; ; # f (t) dt: (7.8.11) 2F 1 dx t ; ; 1; 0; 1 ; c t 0 (iv) The transform 2F 11 is independent of in the sense that if 0 < < min[Re(a); Re(b)] and 0 < e < min[Re(a); Re(b)] and if the transforms 2 F 1 1 and 2g F 1 1 are de ned on L;2 and Le ;2; respectively by (7:8:3); then 2 F 11 f = 2g F 11 f for f 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; 2F 11 f (x) is given in (7:8:1) and (7:8:5).
1
"
d +1 Z 1 2;2 x ; x G3;3 f (x) = ;x
Theorem 7.38. Let 0 < 1 ; < min[Re(a); Re(b)]: (i) There is a one-to-one transform F 2 [L; ] such that (7:8:4) holds for Re(s) = 2
1
2
and f 2 L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation 1
Z 0
holds.
f (x) 2 F 1 g (x)dx = 2
1
Z
2
0
2
F 1 1 f (x)g (x)dx
(iii) Let f 2 L; and 2 C . If Re() > ;; then F 2
F1 f
2
2
2
(x) = ;x+1
When Re() < ;; 2
F1 f 2
(x) = x+1
1
2
f is given by
d ; Z 1 1;3 t ;; 1 ; a; 1 ; b x G3;3 dx x 0; 1 ; c; ; ; 1 0
"
d ; Z 1 2;2 t 1 ; a; 1 ; b; ; x G3;3 dx x ; ; 1; 0; 1 ; c 0 "
(7.8.12)
#
#
f (t) dt: x
(7.8.13)
f (t) dt: x
(7.8.14)
(iv) The transform F is independent of in the sense that if 0 < < min[Re(a); Re(b)] 2
1
2
and 0 < e < min[Re(a); Re(b)] and if the transforms 2 F 1 2 and 2g F 1 2 are de ned on L;2 and Le ;2; respectively by (7:8:4); then 2 F 12 f = 2g F 12 f for f 2 L;2 \ Le ;2.
235
7.8. Modi ed 2 F 1 -Transforms
(v) For f 2 L; and x > 0; F 2
2
1
2
f (x) is given in (7:8:2) and (7:8:6).
From Theorems 6.18, 6.19 and 6.30, 6.31 we obtain the L;r -theory of the transform (7.8.1) and (7.8.2).
Theorem 7.39. Let = min[Re(a); Re(b)], 0 < < and ! = a + b ; c ; . (a) If 1 5 r 5 s 5 1; then the transform F de ned on L; can be extended to L;r 2
1 1 1 1
2
as an element of [L;r ; L;s ]. If 1 5 r 5 2; then 2F is a one-to-one transform from L;r onto
L;s .
(b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L ;;s with 1=s + 1=s0 = 1; then the relation 1
0
(7:8:9) holds. (c) If 1 < r < 1 and the condition (7:8:7) holds; then 2F 11 is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:8:7) holds; then 2
F 1 1(L;r ) =
LL1;1+c;a;b
(L;r );
(7.8.15)
where L and L1;1+c;a;b are given in (2:5:2) and (3:3:3): If (7:8:7) is not valid; then 2F 1 1(L;r ) is a subset of the right-hand side of (7:8:15): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:8:7) holds; then 2
F 1 1 (L;r ) = I;;;1! ;0 LL1;1; (L;r );
(7.8.16)
where I;;;1! ;0 is given in (3:3:2). If (7:8:7) is not valid; then 2F 1 1(L;r ) is a subset of the righthand side of (7.8.16).
Theorem 7.40. Let = min[Re(a); Re(b)], 0 < 1 ; < and ! = a + b ; c ; . (a) If 1 5 r 5 s 5 1; then the transform F de ned on L; can be extended to L;r 2
2 1 2 1
2
as an element of [L;r ; L;s ]. If 1 5 r 5 2; then 2F is a one-to-one transform from L;r onto
L;s .
(b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L ;;s with 1=s + 1=s0 = 1; then the relation 1
0
(7:8:12) holds. (c) If 1 < r < 1 and the condition (7:8:8) holds; then 2F 12 is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:8:8) holds; then 2
F 1 2 (L;r ) =
L;1;1L;1; +!
(L;r );
(7.8.17)
where L1; is given in (3:3:3): If (7:8:8) is not valid; then 2 F 12 (L;r ) is a subset of the righthand side of (7:8:17): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:8:8) holds; then 2
;! L;1;1 L;1; (L;r ); F 1 2(L;r ) = I0+;1 ;0
(7.8.18)
where I;;;1! ;; is given in (3:3:2). If (7:8:8) is not valid; then 2 F 1 2 (L;r ) is a subset of the right-hand side of (7.8.18).
236
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
Now we discuss further generalizations of (7.8.1) and (7.8.2) in the forms x ;1 ;( a);(b) Z 1 1;; (7.8.19) f ( x) = 2F 1 ;(c) x 0 2 F1 a; b; c; ; t t f (t)dt and ;(a);(b) x;1 Z 1 F a; b; c; ; t t f (t)dt 2;; (7.8.20) f (x) = 2 1 2F 1 ;(c) x 0 with a; b; c; ; 2 C (Re(a) > 0; Re(b) > 0). The Mellin transforms of (7.8.19) and (7.8.20) for a \suciently good" function f are given by
M 2 F 1 1;; f (s) = G12;;22(s + ) Mf (s + + )
(7.8.21)
and
M 2F 1 2;; f (s) = G12;;22(1 ; s ; ) Mf (s + + )
(7.8.22)
with G12;;22(s) being de ned in (7.7.3). Then they are modi ed G-transforms (6.2.4) and (6.2.5) of the forms # " Z 1 1 ; a; 1 ; b x 1 ; 2 1;; t;1 f (t)dt (7.8.23) f (x) = x G2;2 2F 1 t 0; 1 ; c 0 and 2
F1
2;
; f
(x) = x;1
Z
1 0
G
; ;
t 1 ; a; 1 ; b t f (t)dt: x 0; 1 ; c
"
12 22
#
(7.8.24)
Now we apply the results in Section 6.6 and 6.7 to obtain the L;2 - and L;r -theory of the transforms (7.8.19) and (7.8.20), by taking into account that from (7.8.7) and (7.8.8) the condition 1 ; + Re() 2= E9 and ; Re() 2= E9 for the exceptional set E9 are equivalent to s 6= c + i (i = 0; 1; 2; ) for Re(s) = ; Re()
(7.8.25)
s 6= c + i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re():
(7.8.26)
and Theorems 6.50 and 6.62 yield the L;2 -theory of the transforms 2 F 11;; and 2 F 1 2;; .
Theorem 7.41. Let 0 < ; Re() < min[Re(a); Re(b)]: (i) There is a one-to-one transform F ; 2 [L; ; L; 2
1
1;
2
for Re(s) = ; Re( + ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L1;+Re(+);2; then the relation 1
Z 0
holds.
f (x) 2 F 1 1;; g (x)dx =
1
Z 0
;
Re( + ) 2
2
] such that (7:8:21) holds
F 1 2;; f (x)g (x)dx
(7.8.27)
237
7.8. Modi ed 2 F 1 -Transforms
(iii) Let f 2 L; and 2 C . If Re() > ; Re() ; 1; then F 2
2
F1
; f
1;
2
(x) = x;
1
; f
1;
is given by
d +1 Z 1 1;3 x ;; 1 ; a; 1 ; b ;1 x G3;3 t f (t)dt: dx t 0; 1 ; c; ; ; 1 0
"
#
(7.8.28)
When Re() < ; Re() ; 1; 2
F1
; f
1;
(x) = ;x;
(iv) The transform F
d +1 Z 1 2;2 x 1 ; a; 1 ; b; ; ;1 x G3;3 t f (t)dt: dx t ; ; 1; 0; 1 ; c 0
"
#
(7.8.29)
is independent of in the sense that if 0 < ; Re() < min[Re( a); Re(b)] and 0 < ; Re() < min[Re(a); Re(b)] and if the transforms 2 F 1 1;; and ; e are de ned on L;2 an Le ;2 ; respectively by (7:8:21); then 2F 1 1;; f = 2Fe 1 ; f for 2F 1 f 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; 2F 11;; f (x) is given in (7:8:19) and (7:8:23). 2
1
;
1;
e
Theorem 7.42. Let 0 < 1 ; + Re() < min[Re(a); Re(b)]: (i) There is a one-to-one transform F ; 2 [L; ; L; ; ] such that (7:8:22) holds 2
1
2;
2
Re( + ) 2
for Re(s) = ; Re( + ) and f 2 L;2 . (ii) If f 2 L;2 and g 2 L1;+Re(+);2; then the relation 1
Z 0
f (x) 2 F 1 2;; g (x)dx =
1
Z
1;; f (x)g (x)dx 2F 1
0
holds.
(iii) Let f 2 L; and 2 C . If Re() > ; + Re(); then F 2
2
F1
; f
2;
2
1
; f
2;
(7.8.30) is given by
d ;;1 Z 1 1;3 t ;; 1 ; a; 1 ; b x G3;3 t f (t)dt: dx x 0; 1 ; c; ; ; 1 0
(7.8.31)
d ;;1 Z 1 2;2 t 1 ; a; 1 ; b; ; x G3;3 t f (t)dt: dx x ; ; 1; 0; 1 ; c 0
(7.8.32)
(x) = ;x++1
"
#
When Re() < ; + Re(); 2
F1
; f
2;
(x) = x++1
(iv) The transform F
"
#
is independent of in the sense that if 0 < 1 ; + Re() < min[Re(a); Re(b)] and 0 < 1 ; e + Re() < min[Re(a); Re(b)] and if the transforms 2 F 12;; and 2 Fe 1 2;; are de ned on L;2 an Le ;2 ; respectively by (7:8:22); then 2 F 12;; f = 2Fe 1 2;; f for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; 2F 12;; f (x) is given in (7:8:20) and (7:8:24). 2
1
;
2;
Theorems 6.54, 6.55 and 6.66, 6.67 give the L;r -theory of the transforms 2 F 1 1;; and 2;; . 2F 1
Theorem 7.43. Let = min[Re(a); Re(b)]; 0 < ; Re() < and ! = a + b ; c ; . (a) If 1 5 r 5 s 5 1; then the transform F ; de ned on L; can be extended to 2
1
1;
2
L;r as an element of [L;r ; L ;Re(+);s ]. If 1 5 r 5 2; then 2 F 1 1;; is a one-to-one transform from L;r onto L ;Re(+);s .
238
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L ; 1
;s
+Re( + )
0
with 1=s + 1=s0 = 1; then the
relation (7:8:27) holds. (c) If 1 < r < 1 and the condition (7:8:25) holds; then 2F 11;; is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:8:25) holds; then 1;; (L;r ) = 2F 1
L1;; L1;1+c;a;b+
(7.8.33)
L ;Re(+);r ;
where L1;; and L1;1+c;a;b+ are given in (3:3:3): If (7:8:25) is not valid; then 2 F 11;; (L;r ) is a subset of the right-hand side of (7:8:33): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:8:25) holds; then 2
F 1 1;; (L;r ) = I;;;1! ; L1;; L1;1; + L ;Re(+);r ;
(7.8.34)
where I;;;1! ; is given in (3:3:2). If (7:8:25) is not valid; then 2F 1 1;; (L;r ) is a subset of the right-hand side of (7.8.34).
Theorem 7.44. Let = min[Re(a); Re(b)]; 0 < 1 ; + Re() < and ! = a + b ; c ; (a) If 1 5 r 5 s 5 1; then the transform F ; de ned on L; can be extended to 2
1
2;
2
L;r as an element of [L;r ; L ;Re(+);s ]. If 1 5 r 5 2; then 2 F 1 2;; is a one-to-one transform from L;r onto L ;Re(+);s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L1;+Re(+);s with 1=s + 1=s0 = 1; then the relation (7:8:30) holds. (c) If 1 < r < 1 and the condition (7:8:26) holds; then 2F 12;; is one-to-one on L;r . (d) Let 1 < r < 1 and Re(!) = 0. If the condition (7:8:26) holds; then 0
2
F 1 2;; (L;r ) =
L;1;1; L;1;a+b;c+
L ;Re(+);r ;
(7.8.35)
where L;1;1; and L;1;a+b;c+ are given in (3:3:3): If (7:8:26) is not valid; then 2 F 12;; (L;r ) is a subset of the right-hand side of (7:8:35): (e) Let 1 < r < 1 and Re(!) < 0. If the condition (7:8:26) holds; then 2
;! F 1 2;; (L;r ) = I0+;1 ;; L;1;1; L;1; + L ;Re(+);r ;
(7.8.36)
;! 2;; where I0+;1 (L;r ) is a subset of the ;; is given in (3:3:1): If (7:8:26) is not valid; then 2F 1 right-hand side of (7.8.36).
7.9. The Generalized Stieltjes Transform As an application of the results in the previous section, we consider the integral transform
S ;; f (x) =
;( + + 1);( + 1) ;( + + + 1)
1 t
Z 0
x
2
F1
t f (t) + + 1; + 1; + + + 1; ; dt x x
(7.9.1)
239
7.9. The Generalized Stieltjes Transform
with ; ; 2 C (Re( + ) + 1 > 0; Re( ) + 1 > 0). When = 0; by the known relation 2 F1 (a; b; a; z ) = 1 F0 (b; z ) = (1 ; z );b , (7.9.1) takes the form Z 1 t f (t) t F + 1; ; dt S f (x) = ;( + 1) 1 0 0 x Z 1 t f (t)dt = ;( + 1) 0 (t + x) +1
;;0
x
x
(7.9.2)
and becomes the Stieltjes transform for = 0: 1
1 f (t)dt: (7.9.3) 0 t+x The transform (7.9.1) is a particular case of the modi ed transform 2 F 12;; (7.8.20) for which = ; ; = ; a = + + 1; b = + 1; c = + + + 1: (7.9.4) The relations (7.8.22), (7.8.24), (7.8.30) and (7.8.26) have the forms ;(1 + ; s);( + s);(s) Mf (s); (7.9.5) MS ;; f (s) = ;( + + s) (Sf )(x) =
Z
1 t 1;2 t ; ; ; ; f (t) G2;2 dt; S ;; f (x) = x x 0; ; ; ; x 0 Z 1 Z 1 f (x) S ;; g (x)dx = S ;; f (x)g (x)dx 0 0
with
S ;; f (x) =
and
Z
0
#
(7.9.6) (7.9.7)
;( + + 1);( + 1) ;( + + + 1)
1 x
t
"
Z
2 F1 + + 1; + 1; + + + 1; ;
x f (t) dt t t
(7.9.8)
s 6= + + + 1 + i (i = 0; 1; 2; ) for Re(s) = 1 ; + Re( ):
(7.9.9) Theorems 7.42 and 7.44 lead to the L;2 - and L;r -theory of the generalized Stieltjes transform S ;; .
Theorem 7.45. Let ;Re( ) < 1 ; < 1 + min[0; Re()]: (i) There is a one-to-one transform S ;; 2 [L;2] such that the relation (7:9:5) holds for
Re(s) = and f 2 L;2 . (ii) If f 2 L;2 and g 2 L1;;2; then the relation (7:9:7) holds for S ;; . (iii) Let f 2 L;2 and 2 C . If Re() > ; + Re( ); then S ;; f is given by
S ;; f (x) d ;;1 Z 1 1;3 t ;; ; ; ; ; ; + +1 x G t f (t)dt: = ;x dx 0 3;3 x 0; ; ; ; ; ; ; 1 "
#
(7.9.10)
240
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
When Re() < ; + Re( );
S ;; f (x)
; ; ; ; ; ; t f (t)dt: (7.9.11) ; ; 1; 0; ; ; ; (iv) The transform S ;; is independent of in the sense that if ;Re( ) < 1 ; < 1 + min[0; Re( )] and ;Re( ) < 1 ; < 1 + min[0; Re( )] and if the transforms S ;; "
#
d ;;1 Z 1 2;2 t x G3;3 = x; ++1 dx x 0 e
and S ;; are de ned on L;2 and Le ;2 ; respectively by (7:9:5); then S ;; f = Se ;; f for f 2 L;2 \ Le ;2. (v) For f 2 L;2 and x > 0; S ;; f (x) is given in (7:9:1) and (7:9:6). e
Theorem 7.46. Let ;Re( ) < 1 ; < 1 + min[0; Re()]. (a) If 1 5 r 5 s 5 1; then the transform S ;; de ned on L;2 can be extended to L;r
as an element of [L;r ; L;s ]. If 1 5 r 5 2; then S ;; is a one-to-one transform from L;r onto L;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L1;;s with 1=s + 1=s0 = 1; then the relation (7:9:7) holds. (c) If 1 < r < 1 and the condition (7:9:9) holds, then S ;; is one-to-one on L;r . (d) Let 1 < r < 1 and Re( ) + min[0; Re()] 5 0. If the condition (7:9:9) holds; then 0
S ;; (L;r ) =
L;1;1+ L;1;1;
(L;r );
(7.9.12)
where L;1;1+ and L;1;1; are given in (3:3:3): If (7:9:9) is not valid; then S ;; (L;r ) is a subset of the right-hand side of (7:9:13): (e) Let 1 < r < 1 and Re( ) + min[0; Re()] > 0. If the condition (7:9:9) holds; then
;! L;1;1+ L;1;0 (L;r ); S ;; (L;r ) = I0+;1 ;
(7.9.13)
;! is given in (3:3:1): If (7:9:9) is not valid, then where ! = ; ; min[0; Re( )] and I0+;1 ; S ;; (L;r ) is a subset of the right-hand side of (7.9.14).
7.10. pF q -Transform Let us investigate the integral transform of the type p
Y
pF q f
(x) =
i=1 q Y j =1
;(ai ) Z 1 ;(bj )
0
p Fq (a1 ; ; ap; b1; ; bq ; ;xt)f (t)dt
(7.10.1)
with ai ; bj 2 C (Re(ai ) > 0; i = 1; 2; ; p; j = 1; 2; q ); for which we take p 2 N and either q = p, q = p + 1 or q = p ; 1. These transforms, containing the generalized hypergeometric function (2.9.2) in the kernel, generalize the transforms 1 F 1 , 1 F 2 and 2 F 1 given in (7.5.1), (7.6.1) and (7.7.1), respectively.
241
7.10. p F q -Transform
Due to Prudnikov, Brychkov and Marichev [3, 8.4.51.1], the Mellin transform of (7.10.1) for a \suciently good" function f is given by the relation
M p F q f (s) = G1p;q;p+1(s) Mf (1 ; s)
with G1p;q;p+1
(7.10.2)
Yp # ;(s) ;(ai ; s) s = i ; Yq ;(bj ; s)
" (1 ; a ) i ;p 0; (1 ; bj ) ;q 1
(7.10.3)
=1
1
j =1
provided that 0 < Re(s) < min Re(ai )
(7.10.4)
5 i5 p
1
for q = p and q = p ; 1; and
0
1
p pX +1 X 0 < Re(s) < min Re(ai ); Re(s) < 14 ; 21 Re @ ai ; bi A 15i5p i=1 i=1
(7.10.5)
for q = p + 1. The relations (7.10.2) and (7.10.3) show that, for the cases q = p; q = p + 1 and q = p ; 1; (7.10.1) is the G-transform (1.5.1) of the forms
pF p f
(x) =
p F p+1 f (x) =
and
pF p;1 f
Z1 0
Z1
(x) =
0
Gp;p;p+1 1
G1p;p;p+2
Z1 0
" 1 ; a ; ; 1 ; a # p xt f (t)dt; 0; 1 ; b ; ; 1 ; bp " 1 ; a ; ; 1 ; a # p xt f (t)dt 0; 1 ; b ; ; 1 ; bp 1
1
1
1
+1
" 1 ; a ; ; 1 ; a # p ;p Gp;p xt f (t)dt: 0; 1 ; b ; ; 1 ; bp; 1
1
1
1
(7.10.6) (7.10.7)
(7.10.8)
For the transforms (7.10.6), (7.10.7) and (7.10.8), the constants a ; ; a1; a2; ; and in (6.1.5){(6.1.11) take the forms a = 1; = 1; a1 = 1; a2 = 0; = 0; = min [Re(ai )]; p X
1 = (ai ; bi) ; ; 2 i=1
5i5p
1
a = 0; = 2; a1 = 1; a2 = ;1; = 0; = min Re(ai ); =
p X i=1
ai ;
pX +1 i=1
5i5p
1
bi ; 1
(7.10.9)
(7.10.10)
242
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
and a = 2; = 0; a1 = 1; a2 = 1; = 0; = min Re(ai); = 5i5p
1
p X i=1
ai ;
pX ;1 i=1
(7.10.11)
bi ;
respectively. According to these relations, the conditions in (7.10.4) and (7.10.5) take the forms 0 < Re(s) <
(7.10.12)
0 < Re(s) < ; Re(s) < ; 41 ; 21 Re()
(7.10.13)
for q = p and q = p ; 1; and for q = p + 1. Let E11 be the exceptional set of the function G1p;q;p+1 (s) in (7.10.3). Considering the poles of the gamma functions ;(bj ; s) (1 5 j 5 q ) in the function G1p;q;p+1 (s), we nd that 2= E11 means that s 6= bj + i (j = 1; 2; ; q ; i = 0; 1; 2; ) for Re(s) = 1 ; :
(7.10.14)
First we state the L;2 - and L;r -theory of the transform (7.10.1) in the case when q = p by using Theorems 6.1, 6.2 and 6.6, 6.8.
Theorem 7.47. Let is be given in (7:10:9) and 0 < 1 ; < : (i) There is a one-to-one transform pF p 2 [L; ; L ;; ] such that (7:10:2) holds for q = p;
Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation
Z1 0
f (x) p F p g (x)dx =
2
1
Z 1
pF p f
0
2
(x)g (x)dx
(7.10.15)
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then pF pf is given by 2
(x)
pF p f
" ;; 1 ; a ; ; 1 ; a # p f (t)dt: 0; 1 ; b ; ; 1 ; bp ; ; ; 1
d +1 Z 1 1;p+1 ; x Gp+1;p+2 xt =x dx
0
1
1
(7.10.16)
When Re() < ;; then p F pf is given by
pF p f
(x)
"
1 ; a1; ; 1 ; ap; ; d +1 Z 1 2;p ; Gp+1;p+2 xt = ;x dx x 0 ; ; 1; 0; 1 ; b1; ; 1 ; bp
#
f (t)dt:
(7.10.17)
243
7.10. p F q -Transform
(iv) The transform pF p is independent of in the sense that if 0 < 1 ; < and 0 < 1 ; e < and if the transforms p F p and p Fe p are de ned on L; an Le ; ; respectively by (7:10:2) with q = p; then p F p f = p Fe p f for f 2 L; \ Le ; . (v) For f 2 L; and x > 0; pF p f (x) is given in (7:10:6) as well as (7:10:1) with q = p. 2
2
2
2
2
Theorem 7.48. Let and be given in (7:10:9); 0 < 1 ; < ; ! = + 1=2 and 1 5 r 5 s 5 1: (a) The transform pF p de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s]. When 1 5 r 5 2; p F p is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:10:15) holds. (c) If 1 < r < 1 and the condition (7:10:14) for q = p holds; then the transform pF p is one-to-one on L;r . (d) If 1 < r < 1; Re(!) = 0 and the condition (7:10:14) for q = p holds; then (7.10.18) pF p (L;r ) = L1;;! (L;r ); where the operator L1;;! is given in (3:3:3): If the condition (7:10:14) for q = p is not valid; then pF p (L;r ) is a subset of the right-hand side of (7:10:18): (e) If 1 < r < 1; Re(!) < 0 and the condition (7:10:14) for q = p holds, then ;! (7.10.19) p F p (L;r ) = I;;1;0L (L;r ); where the operators I;;;1! ;0 and L are given in (3:3:2) and (2:5:2): If the condition (7:10:14) for q = p is not valid; then p F p (L;r ) is a subset of the right-hand side of (7.10.19). 0
Theorems 6.1, 6.2 and 6.5 lead to the L;2 - and L;r -theory of the transform (7.10.1) in the case when q = p + 1.
Theorem 7.49. Let and be given in (7:10:10); 0 < 1; < and 2(1; )+Re() 5 0: (i) There is a one-to-one transform pF p 2 [L; ; L ;; ] such that (7:10:2) holds for +1
2
1
2
q = p + 1; Re(s) = 1 ; and f 2 L;2 . If 2(1 ; ) + Re() = 0 and if the condition (7:10:14) with q = p + 1 holds, then the transform pF p+1 maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then the relation
Z1 0
holds.
f (x) p F p+1 g (x)dx =
Z 1 0
pF p+1 f
(x)g (x)dx
(iii) Let f 2 L; and 2 C . If Re() > ;; then p F p 2
p F p+1 f
(x)
+1
When Re() < ;; p F p+1 f (x)
f is given by
;; 1 ; a ; ; 1 ; a
" d +1 Z 1 1;p+1 ; Gp+1;p+3 xt = x dx x 0
1
(7.10.20)
p
#
0; 1 ; b1; ; 1 ; bp+1 ; ;( + 1)
"
1 ; a1; ; 1 ; ap; ; d +1 Z 1 2;p ; Gp+1;p+3 xt = ;x dx x 0 ; ; 1; 0; 1 ; b1; ; 1 ; bp+1
#
f (t)dt:
(7.10.21)
f (t)dt:
(7.10.22)
244
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(iv) The transform pF p is independent of in the sense that if 0 < 1 ; < ; 2(1 ; )+Re() 5 0 and 0 < 1 ; e < ; 2(1 ; e)+Re() 5 0 and if the transforms p F p and p Fe p are de ned on L; and Le; ; respectively by (7:10:2) with q = p + 1; then p F p f = p Fe p f for f 2 L; \ Le; . (v) If 2(1 ; )+Re() < 0; then for f 2 L; and x > 0; pF p f (x) is given in (7:10:7) +1
+1
+1
2
+1
2
+1
2
2
2
as well as (7:10:1) with q = p + 1.
+1
Theorem 7.50. Let and be given in (7:10:10); 0 < 1 ; < ; 1 < r < 1 and
2(1 ; ) + Re() 5 1=2 ; (r); where (r) is de ned in (3:3:9): (a) The transform pF p+1 de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; 2(1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; the transform pF p+1 is one-to-one on L;r and there holds the equality (7:10:2) with q = p + 1 and Re(s) = 1 ; . (c) If f 2 L;r and g 2 L;s with 1 < s < 1; 1=r + 1=s = 1 and 2(1 ; ) + Re() 5 1=2 ; max[ (r); (s)]; then the relation (7:10:20) holds. (d) If the condition (7:10:14) with q = p +1 holds; then the transform pF p+1 is one-to-one on L;r . If we set = ; ; 1; then Re( ) > ;1 and there holds p F p+1 (L;r ) =
M(+1)=2H 2;
(7.10.23)
L ;Re()=2;1=2;r ;
where M and H 2; are given in (3:3:11) and (3:3:4): When the condition (7:10:14) with q = p + 1 is not valid; then p F p+1 is a subset of the right-hand side of (7:10:23): (e) If f 2 L;r with 2 C and 2(1 ; ) + Re() 5 1=2 ; (r); then pF p+1f is given in (7:10:21) for Re() > ;; while in (7:10:22) for Re() < ; . If 2(1 ; ) + Re() < 0; p F p+1 f is given in (7:10:7) as well as (7:10:1) with q = p + 1. For the case q = p + 1; we can apply the inversion formulas in Theorems 6.12 and 6.13.
Theorem 7.51. Let and be given in (7:10:10); 0 < 1 ; < ; 2 C and 0 = 1 ; min [Re(bj )]. 15j 5p+1 (a) If > 0 and 2(1 ; ) + Re() = 0; then for f 2 L;2 the inversion formulas f (x) = x;
d +1 x dx
Z1 0
and f (x) = ;x;
;1 Gpp+1 +1;p+3
" ;; a ; 1; ; a ; 1 # p xt p F p f (t)dt (7.10.24) b ; 1; ; bp ; 1; 0; ; ; 1 1
+1
1
+1
d +1 x dx
" a ; 1; ; a ; 1; ; # p xt p F p f (t)dt (7.10.25) ; ; 1; b ; 1; ; bp ; 1; 0 hold for Re() > ; 1 and Re() < ; 1; respectively. Z1 0
;0 Gpp+2 +1;p+3
1
+1
1
+1
245
7.10. p F q -Transform
(b) Let 1 < r < 1;
0 < < Re( + 1=2)=2 + 1 and 2(1 ; ) + Re() 5 1=2 ; (r); where (r) is given in (3:3:9). If f 2 L;r ; then the relations (7:10:24) and (7:10:25) hold for Re() > ; 1 and for Re() < ; 1; respectively.
Lastly we obtain the L;2 - and L;r -theory of the transform (7.10.1) in the case when q = p ; 1 from Theorems 6.1, 6.2 and 6.6, 6.7.
Theorem 7.52. Let p = 1; be given in (7:10:11) and 0 < 1 ; < : (i) There is a one-to-one transform pF p; 2 [L; ; L ;; ] such that (7:10:2) holds for 1
q = p ; 1; Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then the relation
Z1 0
f (x) p F p;1 g (x)dx =
2
Z 1 0
1
pF p;1 f
2
(x)g (x)dx
(7.10.26)
holds.
(iii) Let f 2 L; and 2 C . If Re() > ;; then pF p; f is given by 2
pF p;1 f
1
(x)
"
#
"
#
;; 1 ; a1; ; 1 ; ap d +1 Z 1 1;p+1 x Gp+1;p+1 xt = x; dx 0 0; 1 ; b1; ; 1 ; bp;1; ; ; 1
f (t)dt:
(7.10.27)
f (t)dt:
(7.10.28)
When Re() < ;;
p F p;1 f
(x)
1 ; a1; ; 1 ; ap; ; d +1 Z 1 2;p ; Gp+1;p+1 xt = ;x dx x 0 ; ; 1; 0; 1 ; b1; ; 1 ; bp;1
(iv) The transform pF p;1 is independent of in the sense that if 0 < 1 ; < and 0 < 1 ; e < and if the transforms p F p;1 and p Fe p;1 are de ned on L;2 and Le ;2 ; respectively by (7:10:2) with q = p ; 1; then p Fp;1 f = pFe p;1 f for f 2 L;2 \ Le ;2 . (v) For f 2 L;2 and x > 0; pF p;1 f (x) is given in (7:10:8) as well as (7:10:1) with q = p ; 1. Theorem 7.53. Let p = 1; and be given in (7:10:11); 0 < 1 ; < ; ! = ; + 1
and 1 5 r 5 s 5 1: (a) The transform pF p;1 de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ]. If 1 5 r 5 2; then p F p;1 is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (7:10:26) holds. (c) If 1 < r < 1 and the condition (7:10:14) for q = p ; 1 holds; then pF p;1 is a one-to-one transform on L;r . (d) If 1 < r < 1; Re(!) = 0 and the condition (7:10:14) for q = p ; 1 holds, then 0
p F p;1 (L;r ) = LL1;;
(L1;;r );
(7.10.29)
246
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
where the operators L and L1;; are given in (2:5:2) and (3:3:3): If the condition (7:10:14) for q = p ; 1 is not valid; then p F p;1 (L;r ) is a subset of the right-hand side of (7:10:29): (e) If 1 < r < 1; Re(!) < 0 and the condition (7:10:14) for q = p ; 1 holds, then ;! (7.10.30) pF p;1 (L;r ) = I;;1;0 LL1;1; (L1;;r ); where the operator I;;;1! ;0 is given in (3:3:2): If the condition (7:10:14) for q = p ; 1 is not valid, then p F p;1 (L;r ) is a subset of the right-hand side of (7.10.30).
7.11. The Wright Transform
We consider the integral transform of the form Z 1 " (ai; i)1;p # (7.11.1) xt f (t)dt p q f (x) = p q 0 (bj ; j )1;q containing the Wright function p q (z ) de ned in (2.9.30) in the kernel. Due to (2.9.29) this transform is the H -transform (3.1.1) of the form " (1 ; a ; ) # Z1 i i 1;p 1;p Hp;q+1 xt f (t)dt: (7.11.2) p q f (x) = 0 (0; 1); (1 ; bj ; j )1;q Therefore the Mellin transform of (7.11.1) is given by M p q f (s) = H1p;q;p+1(s) Mf (1 ; s); (7.11.3) where H1p;q;p+1 (s) = H1p;q;p+1
p Y # ;(s) ;(ai ; is) s = i : Yq ;(bj ; j s)
" (1 ; a ; ) i i ;p (0; 1); (1 ; bj ; j ) ;q 1
=1
1
(7.11.4)
j =1
Applying the results in Sections 3.6 and 4.1{4.8, we can construct the L;2 - and L;r -theory of the transform (7.11.1) by taking into account that the constants a ; ; ; ; a1; a2; and in (1.1.7){(1.1.13), (3.4.1) and (3.4.2) have the forms a =
=
p X
i=1 q X
p X i=1
j ;
j =1 Yp
= =
i ;
i=1
ai ;
q X
j =1 p X
j =1
a1 = 1; a2 =
(7.11.5)
i + 1;
(7.11.6)
j j ;
(7.11.7)
i=1 Yq
;i i q X
j + 1;
j =1
bj ; p X i=1
p;q+1
i ;
2
q X j =1
j
;
(7.11.8) (7.11.9)
247
7.11. The Wright Transform
and
Re( ai ) : = 0; = min
(7.11.10)
15i5p i Let E12 be the exceptional set of the function H1p;q;p+1 (s) in (7.11.4) and s 2= E12 means that b +i (i = 0; 1; 2; ; j = 1; ; q ) for Re(s) = 1 ; : (7.11.11) s 6= j j
Now Theorems 3.6 and 3.7 lead to the L;2 -theory of the transform (7.11.1).
Theorem 7.54. Let a; ; and be given in (7:11:5); (7:11:6); (7:11:8) and (7:11:10): We suppose that (a) 0 < 1 ; < and that either of conditions (b) a > 0; or (c)
a = 0; (1 ; ) + Re() 5 0 holds. Then we have the following results: (i) There is a one-to-one transform p q 2 [L;2; L1;;2] such that (7:11:3) holds for Re(s) = 1 ; and f 2 L;2 . If a = 0; (1 ; ) + Re() = 0 and the condition (7:11:11) holds; then the transform p q maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then the relation 1
Z
0
holds.
f (x)
p q g (x)dx =
Z
1
0
p qf
(x)g (x)dx
(7.11.12)
(iii) Let f 2 L;2; 2 C and h > 0. If Re() > (1 ; )h ; 1; then p q f is given by 1;(+1)=h d x(+1)=h p q f (x) = hx dx
Z
# (;; h); (1 ; ai ; i )1;p f (t)dt: (7.11.13) p+1;q+2 xt (0; 1); (1 ; bj ; j )1;q ; (; ; 1; h)
1 1;p+1 H
0
"
When Re() < (1 ; )h ; 1;
p qf
d (+1)=h x (x) = ;hx1;(+1)=h dx
# (1 ; ai ; i )1;p; (;; h) xt f (t)dt: (7.11.14) 0 p+1;q+2 (; ; 1; h); (0; 1); (1 ; bj ; j )1;q (iv) The transform p q is independent of in the sense that if and e satisfy (a), and e (b) or (c), and if the transforms p q and p q are de ned on L;2 and Le ;2 ; respectively by (7:11:3); then p q f = p e q f for f 2 L;2 \ Le ;2 . (v) If either (b) a > 0 or (d) a = 0; (1 ; ) + Re() < 0; then for f 2 L;2 and x > 0; p q f (x) is given in (7:11:1) and (7.11.2). Z
1 2;p H
"
From Theorems 4.1, 4.2 and 4.3, 4.4 we obtain the L;r -theory of the transform (7.11.1) in the case when a = 0.
Theorem 7.55. Let a; ; and given in (7:11:5); (7:11:6); (7:11:8) and (7:11:10) be
such that a = = 0; Re() = 0 and 0 < 1 ; < :
248
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(a) The transform p q de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;r ]
for 1 < r < 1. (b) If 1 < r 5 2; the transform p q is one-to-one on L;r and there holds the equality (7:11:3) for f 2 L;r . (c) If the condition (7:11:11) is satis ed; then p q is one-to-one on L;r and there holds
p q (L;r ) = L1;;r :
(7.11.15)
(d) If f 2 L;r and g 2 L;r0 with 1 < r < 1 and r0 = r=(r ; 1); then the relation
(7:11:12) holds. (e) If 1 < r < 1; f 2 L;r ; 2 C and h > 0; then p q f is given in (7:11:13) for Re() > (1 ; )h ; 1; while p q f in (7:11:14) for Re() < (1 ; )h ; 1.
Theorem 7.56. Let a; ; and given in (7:11:5); (7:11:6); (7:11:8) and (7:11:10) be
such that a = = 0; Re() < 0 and 0 < 1 ; < . (a) Let 1 < r < 1. The transform p q de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s = r such that 1=s > 1=r + Re(). (b) If 1 < r 5 2; then p q is a one-to-one transform on L;r and there holds the equality (7:11:3): (c) If the condition (7:11:11) is satis ed; then the transform p q is one-to-one on L;r and there hold ; p q (L;r ) = I;;k;0 (L1;;r )
(7.11.16)
; p q (L;r ) = I0+;k; =k;1 (L1;;r )
(7.11.17)
for k = 1; and
; for 0 < k 5 1 and p > 0; where the operators I;;;k;0 and I0+; k; =k;1 are de ned in (3:3:1) and (3:3:2). If the condition (7:11:11) is not satis ed; p q (L;r ) is a subset of the right-hand sides of (7:11:16) and (7:11:17) in the respective cases. (d) If f 2 L;r and g 2 L;s with 1 < r < 1; 1 < s < 1 and 1 5 1=r + 1=s < 1 ; Re(); then the relation (7:11:12) holds. (e) If 1 < r < 1; f 2 L;r ; 2 C and h > 0; then p q f is given in (7:11:13) for Re() > (1 ; )h ; 1; while p q f in (7:11:14) for Re() < (1 ; )h ; 1. Furthermore p q f is given in (7:11:1) and (7.11.2).
Theorem 7.57. Let a; ; and given in (7:11:5); (7:11:6); (7:11:8) and (7:11:10) be
such that a = 0; 6= 0; 0 < 1 ; < ; 1 < r < 1 and (1 ; ) + Re() 5 1=2 ; (r); where (r) is de ned in (3:3:9): Further assume that p > 0 if < 0. (a) The transform p q de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [1=2 ; (1 ; ) ; Re()];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; the transform p q is one-to-one on L;r and there holds the equality (7:11:3): (c) If the condition (7:11:11) is satis ed; then the transform p q is one-to-one on L;r . If we set = ; ; 1 for > 0 and = ; ; ; 1 for < 0; then Re( ) > ;1 and there
249
7.11. The Wright Transform
holds
p q (L;r ) =
M=+1=2H;
L ;Re()=;1=2;r :
(7.11.18)
If the condition (7:11:11) is not satis ed; p q (L;r ) is a subset of the right-hand side of (7:11:18): (d) If f 2 L;r and g 2 L;s with 1 < s < 1; 1=r +1=s = 1 and (1 ; )+Re() 5 1=2 ; max[ (r); (s)]; then the relation (7:11:12) holds. (e) If f 2 L;r ; 2 C ; h > 0 and (1 ; ) + Re() 5 1=2 ; (r); then p q f is given in (7:11:13) for Re() > (1 ; )h ; 1; while p q f in (7:11:14) for Re() < (1 ; )h ; 1. If (1 ; ) + Re() < 0; p q f is given in (7:11:1) and (7:11:2). From Theorems 4.5{4.7 and 4.9 we obtain the L;r -theory of the transform (7.11.1) in the case when a 6= 0.
Theorem 7.58. Let a and given in (7:11:5) and (7:11:10) be such that a
> 0;
0 < 1 ; < and 1 5 r 5 s 5 1: (a) The transform p q de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ]. When 1 5 r 5 2; the transform p q is one-to-one from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s0 with 1=s + 1=s0 = 1; then the relation (7:11:12) holds.
Theorem 7.59. Let ; a2 and given in (7:11:8); (7:11:9) and (7:11:10) be such that
a2 > 0; 0 < 1 ; < and ! = ; a2 + 1 and let 1 < r < 1: Let further p > 0. (a) Let the condition (7:11:11) be satis ed; or if 1 5 r 5 2; then the transform p q is one-to-one on L;r . (b) If Re(!) = 0 and the condition (7:11:11) is satis ed; then
p q (L;r ) = LLa2 ;1; ;!=a2
(L1;;r );
(7.11.19)
where L and Lk; are given in (2:5:2) and (3:3:3): If the condition (7:11:11) is not satis ed; then p q (L;r ) is a subset of the right-hand side of (7:11:19): (c) If Re(!) < 0 and the condition (7:11:11) is satis ed; then p q (L;r ) =
I;;;1! ;0LLa2 ;1; (L1;;r );
(7.11.20)
where I;;;1! ;0 is given in (3:3:2): If the condition (7:11:11) is not satis ed; then p q (L;r ) is a subset of the right-hand side of (7.11.20).
Theorem 7.60. Let ; a2 and given in (7:11:8); (7:11:9) and (7:11:10) be such that
a = 0; 0 < 1 ; <
and ! = + 1=2 and let 1 < r < 1: (a) Let the condition (7:11:11) be satis ed; or if 1 < r 5 2; then p q is a one-to-one transform on L;r . (b) If Re(!) = 0 and the condition (7:11:11) is satis ed; then 2
p q (L;r ) = L1;;! (L;r );
(7.11.21)
where L1;;! is given in (3:3:3): If the condition (7:11:11) is not satis ed; then p q (L;r ) is a subset of the right-hand side of (7:11:21):
250
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
(c) If Re(!) < 0 and the condition (7:11:11) is satis ed; then ;! p q (L;r ) = I;;1;0 L (L;r );
(7.11.22)
where I;;;1! ;0 and L are given in (3:3:2) and (2:5:2): If the condition (7:11:11) is not satis ed; then p q (L;r ) is a subset of the right-hand side of (7.11.22).
Theorem 7.61. Let a; ; a2 and given in (7:11:5); (7:11:8); (7:11:9) and (7:11:10) be
such that a > 0; a2 < 0; 0 < 1 ; < and let 1 < r < 1: (a) Let the condition (7:11:11) be satis ed; or if 1 < r 5 2; then the transform p q is one-to-one on L;r . (b) Let !; ; be chosen as 1 (7.11.23) ! = a ; ; ; 2 a Re( ) = (r) + 2a2( ; 1) + Re(); Re( ) > ; 1; (7.11.24) Re( ) < 1 ; ;
(7.11.25)
where (r) is given in (3:3:9): If the condition (7:11:11) is satis ed; then
p q (L;r ) =
M1=2+!=(2a2 )H;2a2 ;2a2 +!;1 L;a ;1=2+;!=(2a2 )
L3=2+Re(!)=(2a2 );;r :
(7.11.26)
If the condition (7:11:11) is not satis ed; then p q (L;r ) is a subset of the right-hand side of (7.11.26). If a = 0; from (4.9.1) and (4.9.2) we get the inversion formulas for the transform (7.11.1): d (+1)=h x dx " Z 1 (;; h); (a ; ; ) i i i 1;p; q; 1 H p+1;q+2 xt 0 (bj ; j ; j )1;q ; (0; 1); (; ; 1; h)
#
d f (x) = ;hx1;(+1)=h x(+1)=h dx " Z 1 (a ; ; ) i i i 1;p; (;; h) q +1 ; 0 H p+1;q+2 xt 0 (; ; 1; h); (bj ; j ; j )1;q ; (0; 1);
#
f (x) = hx1;(+1)=h
and
p qf
(t)dt (7.11.27)
p q f (t)dt; (7.11.28)
respectively. Then Theorems 4.11, 4.12 and 4.13, 4,14 imply the conditions of the inversion formulas (7.11.27) and (7.11.28) for the transform (7.11.1) in the cases when = 0 and 6= 0; respectively. The constants 0 and 0 in (4.9.6) and (4.9.7) take the forms #
"
Re(bj ) ; = 1: 0 = 1 ; min 0 15j 5q
j
(7.11.29)
251
7.12. Bibliographical Remarks and Additional Information on Chapter 7
Theorem 7.62. Let a; ; ; and 0 be given in (7:11:5); (7:11:6); (7:11:8); (7:11:10)
and (7:11:29): Let a = 0; 0 < 1 ; < ; 0 < < 0; 2 C and h > 0: (a) If (1 ; ) + Re() = 0 and if f 2 L;2; the inversion formula (7:11:27) holds for Re() > h ; 1 and (7:11:28) for Re() < h ; 1. (b) If = Re() = 0 and if f 2 L;r (1 < r < 1); then the inversion formula (7:11:27) holds for Re() > h ; 1 and (7:11:28) for Re() < h ; 1.
Theorem 6.63. Let a; ; ; and 0 be given in (7:11:5); (7:11:6); (7:11:8); (7:11:10)
and (7:11:29). Let a = 0 and (1 ; ) + Re() 5 1=2 ; (r); where (r) is given in (3:3:9); and let 1 < r < 1; 2 C and h > 0: (a) If > 0; 0 < 1 ; < ; 0 < < Re( + 1=2)= + 1 and if f 2 L;r ; then the inversion formulas (7:11:27) and (7:11:28) hold for Re() > h ; 1 and for Re() < h ; 1; respectively. (b) If p > 0; < 0; 0 < 1 ; < ; max[ 0; fRe( + 1=2)=g + 1] < < 0 and if f 2 L;r ; then the inversion formulas (7:11:27) and (7:11:28) hold for Re() > h ; 1 and for Re() < h ; 1; respectively.
7.12. Bibliographical Remarks and Additional Information on Chapter 7 The results presented in Sections 7.1{7.11 were obtained by the authors and have not been published before except those in Section 7.9. Below we give historical comments and a review of other investigations connected with the integral transforms of hypergeometric type. For Section 7.1. The classical theory of the Laplace transform L in (2.5.2), in particular its properties in the space L2(R+ ), is well known, for which see the books by Doetsch [1], [2], Widder [1], Titchmarsh [3], Sneddon [1] and Ditkin and Prudnikov [1]. The Laplace transform of generalized functions was considered by Zemanian [6] and by Brychkov and Prudnikov [1, Section 3.4]. The existence and the range of the generalized Laplace transform Lk; given in (3.3.3) in the space L;r presented in Theorem 3.2(c) was proved by Rooney [6, Theorem 5.1(d)]. McBride and Spratt [1] studied the range and invertibiliy of the generalized Laplace type transform Nm given in (5.7.10) in L;r . In particular, they proved in [1, Theorem 5.4] that, if 2 C , 2 C and m > 0 are such that Re( ; =m) > 0, then for the transform Nm on L;r (1 5 r < 1) there holds the following inversion formula
n;; N f (x) (f 2 L;r ); f(x) = nlim L m !1 m
(7.12.1)
where (for suciently large n) ;(+ )
n Ln;; m g (x) = ;(n)
Wn;1=m Km+ +n;; ;ng (x) (g 2 Fr; ):
(7.12.2)
Here W is given in (3.3.12) and Km; = I; ;m; is the Erdelyi{Kober type operator (3.3.2) de ned in terms of the Mellin transform by (3.3.7) for f 2 Fr; (1 5 r 5 2), where the space Fr; is de ned in (5.7.8), 2 C , 2 C and m > 0 such that Re( + =m) 6= ;j (j = 0; 1; 2; ). By (5.7.10) one may deduce from (7.12.1) and (7.12.2) the corresponding inversion formula for the generalized Laplace transform L ;k;; given in (7.1.10).
For Section 7.2. The transform M k;m de ned by (7.2.1) was introduced by Meijer [3] (1941) and is given his name. Meijer [3], [4] has proved the inversion formula for the transform M k;m in the
252
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
form 1 ;(1 ; k + m) Z +iR (xt)k;1=2ext=2M (xt) M f f(x) = Rlim k;m (t)dt; k;1=2;m !1 2i ;(1 + 2m)
;iR
(7.12.3)
where Mk;1=2;m(z) is the Whittaker function de ned via the con uent hypergeometric function of Tricomi (7.2.3) by Mk;1=2;m(z) = e;z=2 z 2m+1 (1 ; k + m; 2m + 1; z) (7.12.4) (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 6.9(1)]). Meijer [3], [4] gave sucient conditions on f(x) under which (7.12.3) follows from (7.2.1) in the case k 5 m 5 ; k, and under which (7.2.1) is a consequence of (7.12.3), when Re(k) 5 ; Re(m) < 1=2: It should be noted that, when k = ;m, the relation (7.2.1) is reduced to the Laplace transform L in (2.5.2), while (7.12.3) is reduced to the inverse Laplace transform L;1 known as a complex inversion formula. Saksena [3] constructed a real inversion formula for the Meijer transform (7.2.1), analogous ; , which is to that constructed by Widder [1] for the Laplace integral, with the aid of the operator K; one of the so-called Kober fractional integration operators de ned for > 0 by ; ; Z x t x + f(t)dt; (7.12.5) I; f (x) I0+;1; f (x) = ;( ) 1; 0 (x ; t) Z 1 t;; ; f (x) I f (x) = x (7.12.6) K; ;;1; ;( ) x (t ; x)1; f(t)dt (see Samko, Kilbas and Marichev [1, (18.5){(18.6)]). Saksena [3] de ned sequences of di erential operators n d k+m n n ; k ; m (7.12.7) U nf (x) = (;1) x dx [x f(x)] and proved the inversion formula in the form 1 (x > 0); (7.12.8) f(x) = nlim !1 t;(n) U n M k;mf (t) t=n=x provided that f(t) is bounded for 0 < t < 1. He also deduced necessary and sucient conditions for a given function g(x) to be represented by the integral g(x) = (M k;mf)(x) with bounded f(x). K.J. Srivastava [1] applied the Kober operators (7.12.5) and (7.12.6) to the investigation of the Meijer transform M k;m as the operator acting from Lr (R+ ) into Lr0 (R+ ) for 1 5 r 5 2 (1=r + 1=r0 = 1). We also indicate some other investigations of the Meijer transform M k;m in (7.2.1). Arya [3] studied the convergence and some properties of the Meijer type transform of the form (7.2.1) in which f(t)dt is replaced by da(t) with a special function a(t). Misra [1] gave Abelian and Tauberian theorems for the transform M k;m . Mehra [1], [3] studied some operational properties of the transform (7.2.1). In particular, he considered the images of the Meijer transforms which are self-reciprocal in the Hankel transform (8.1.1). Pathak and Rai [1] proved certain Abelian (initial and nal value) theorems for the Meijer transform M k;m . The Varma transform V k;m in (7.2.15) is a generalization of the Laplace integral transform L in (2.5.2), when k+m = 1=2. Saksena [1] (1953) probably rst called this transform the Varma transform. Varma himself in [3] (1951) studied some properties of a more general transform than (7.2.15) of the form 1
Z
0
(xt)m;1=2 e;xt=2Wk;m (xt)da(t)
(7.12.9)
with a certain function a(x) and, in particular, he gave several real inversion formulas for such a transform. Earlier Varma in [1] (1947) obtained for the transform x
1
Z
0
(2xt);1=4Wk;m (2xt)f(t)dt
(7.12.10)
253
7.12. Bibliographical Remarks and Additional Information on Chapter 7
theorems which are analogous to certain results for the Laplace transform (2.5.2), while in [2] (1949) he derived a complex inversion formula for the transform (7.12.10). Saksena [1] established three inversion formulas for the transform V k;m which correspond to an inversion for the Laplace transform L in (2.5.2). In [2] and [4] Saksena proved representations for the Varma transform (7.2.15) as compositions of the Laplace operator L and the Kober operators (7.12.5) and (7.12.6). The representations by Saksena can be obtained from (7.2.30) and (7.2.31) and have the forms
V k;mf
and
V k;mf
(x) =
LI2+m;1=2;k;mf
(x)
(7.12.11)
(x) = K0;;m;k;1=2x2m Lx2m f (x): (7.12.12) By using such representations Saksena proved a real inversion formula for the Varma transform. Similar results were also obtained by R.K. Saxena [7], Kalla [1], [3], Pathak [6] and Habibullah [2] for the Varma transform (7.2.15) and by Habibullah [3] for the transform of the form (7.2.15), in which the Whittaker function Wk;m (xt) given in (7.2.2) is replaced by the Whittaker function Mk;m (xt) given in (7.12.4). We also indicated that Fox [5] established the inversion formula for the Varma transform V k;m in terms of the direct L and inverse L;1 Laplace transforms. Gupta [3] established connections between the Meijer and Varma transforms given in (7.2.1) and (7.2.15). Connections of the Varma transform V k;m with the Hankel transform H in (8.1.1) and the Meijer transform K in (8.9.1) were studied by R.K. Saxena [4] and Gupta [1], respectively. R.K. Saxena and K.C. Gupta [1] and Kalla and Munot [1] obtained several theorems involving the Laplace transform (2.5.2) and the Varma transform (7.2.15). Saigo, Goyal and S. Saxena [1] proved a relationship between L, V k;m and the fractional integral, more general than the Riemann{Liouville fractional integral I; in (2.7.2), involving the general class of polynomials and a generalized polynomial set. Kesarwani [2]{[7] and R.K. Saxena [1]{[3], [5]{[6] studied the properties of the simple modi cation of the Varma transform (7.2.15) in the form x
Z
1
0
(xt)m;1=2e;xt=2 Wk;m (xt)f(t)dt:
(7.12.13)
Pathak in [7] and [8] extended the Varma transform (7.2.15) and the Meijer transform M k;m in (7.2.1) to certain spaces of generalized functions and investigated properties such as analyticity, the inversion relation, uniqueness, characterization and the structure formulas. Tiwari [1] obtained similar results for the transform V k;m in another space of tested functions (see Brychkov and Prudnikov [1, Sections 7.1 and 7.2] in this connection). For Section 7.3.
H.M. Srivastava [5] (1968) rst considered the generalized Whittaker transform
W k; in (7.3.1) and proved that if f(x) 2 L (R ) and ;k 5 5 k + 1=2, then an inversion formula for the transform W k; is given via the inverse Laplace transform L; and the Kober fractional ; 2
+
1
integration operator K1+k;;k+ in (7.12.6) by f(x) =
; L;1 K1+ k;;k+
k f W;
(x):
(7.12.14)
Pathak [5] gave two other inversion relations for the generalized Whittaker transform (7.3.1). The rst one has the form
; k f(x) = M;(k+ +1=2) L;1 M;(k+ +1=2) K1+ k;;+ ;1=2W ; f (x);
(7.12.15)
where M;(k+ +1=2) is the elementatry operator (3.3.11), provided that 1 + k > max[j j; ; 1=2],
+ > 1=2 and f(x) 2 L2 (R+ ), xk+ +1=2f(x) 2 L2 (R+ ). The second inversion relation is given by f(x) =
L;1 (Kk;+ +1=2;1=2; ;);1
W k; f
(x);
(7.12.16)
254
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
provided that ;k ; 1 < < 1=2 ; , f(x) 2 L2 (R+ ) and the right-hand side of (7.12.16) exists. Nasim [3] derived the inversion operators in terms of certain di erential operators, for the operator W k; and for the operator of the form (7.3.1) with W; (xt) being replaced by M; (xt) given in (7.12.4). Srivastava and Vyas [1] obtained the relationship between the transform W k; and the generalized Hankel transform given in (8.14.57). Srivastava [6] (1968) introduced the generalization of the Whittaker transform (7.3.1) in the form
S; q;k;m f
(x) =
1
Z 0
(xt);1=2 e;qxt=2Wk;m (pxt)f(t)dt;
(7.12.17)
investigated its inversion formula and obtained the relation of this transform with the Hardy transform (8.14.51). Srivastava, Goyal and Jain [1] studied the relationship between the transform (7.12.17) and the fractional integral, more general than the Riemann{Liouville fractional integral I; in (2.7.2), involving the general class of polynomials. Tiwari [4], [5], Tiwari and Ko [1] and Rao [9] extended the generalized Whittaker transform S ; q;k;m in (7.12.17) to certain spaces of generalized functions and discussed such properties as smoothness, the inversion formula and uniqueness. Tiwari [4] also proved some Abelian theorems for this transform. Carmichael and Pathak [1] considered the transform S ; q;k;m f (x) for complex x 2 C , studied its behavior as x ! 1 and as x ! 0 provided that f(t) has a certain behavior when t ! 0+ or t ! 1, respectively, and extended the results obtained to a certain space of generalized functions described previously by Pathak [7]. We also mention C.K. Sharma [1] who established some properties of the transform, more general than the transform (7.3.1) involving the H-function. Banerjee [1] (1961) and Mainra [1] (1961) probably rst considered further modi cations of the generalized Whittaker transform (7.3.13) in the forms 1
Z 0
(2xt)m;1=2e;pxt=2 (a; c; 2xt)f(t)dt
and
;;1=2 W
k+1=2;m;1;0f
(x) = x
1
Z 0
(xt);;1=2e;xt=2Wk+1=2;m (xt)f(t)dt;
(7.12.18) (7.12.19)
respectively. We note that, in accordance with (7.2.2), the transform in (7.12.18) with the Tricomi hypergeometric function (7.2.3) in the kernel is the generalized Whittaker transform of the form (7.3.13). Banerjee [1] also introduced the transform of the form (7.12.18) in which (a; c; 2xt) is replaced by another con uent hypergeometric function (a; c; 2xt) (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, Chapter VI]) and proved the inversion formulas for these transforms. Bora [1] proved two results for the transform (7.12.18). Mainra [1] studied (7.12.19) with complex x 2 C (Re(x) > 0) and proved several properties, in particular an analogy of the relation (7.3.16) and an inversion formula. Gupta [3] proved a theorem connecting the transform (7.12.19) and a generalized Stieltjes transform. U.C. Jain [2] and Parashar [2] established some other properties for the transform (7.12.19). R.P. Goyal [1] investigated the convergence of the generalized Whittaker transform of the form 1
Z 0
(2xt)Wk;m (2xt)da(t);
(7.12.20)
where a(t) is a normalized function of bounded variation. Habibullah [3] considered the integral transform of the form (7.12.18) x
Z 0
1
(xt)a;1 (a; c; ;xt)f(t)dt;
(7.12.21)
proved its representation as a composition of the transforms generalizing Stieltjes' and Laplace's, (7.9.3) and (2.5.2), and apply this result to investigate the boundedness of the transform (7.12.21)
255
7.12. Bibliographical Remarks and Additional Information on Chapter 7
from Lp (R+ ) (p = 1) into Lq (R+ ) (1=q = 1 ; 1=p ; = 0). We also mention Arya [4] who proved the Abelian theorem for the integral transform Z
0
1
(xt)2m e;xt (;k + m; m + 1; xt)da(t):
(7.12.22)
The transform D in (7.4.1) was de ned and studied by Saksena [6] in a special space of generalized functions, in which the properties such as analyticity, the inversion formula and characterization were investigated (see the book by Brychkov and Prudnikov [1, Sections 7.8]). Mahato and Saksena [1]{[3] studied the transform D in other spaces of tested and generalized functions and indicated the application to solve a special boundary value problem. We also indicate that earlier Saksena in [5] obtained in terms of the transform D the following inversion formula for the Laplace transform (2.5.2): For Section 7.4.
L;1 f
(x)
k+1 2; ;(k+1)=2 Z 1 k ; ;k=2e;k2 =(8xt)Dk+2 ;1 pk p Lf (t)dt (7.12.23) (xt) = klim !1 ;(k + 1) 0 2xt under certain conditions on f(x). Marichev and Vu Kim Tuan [1], [2] (see also Samko, Kilbas and Marichev [1, Theorem 36.14]) stud;xt=2D ;p2xt ied the isomorphic property of the modi cation of the integral transform (7.4.1) with e p being replaced by e;x=(2t)D 2x=t . They proved two composition representations for such a transform in terms of the Riemann{Liouville fractional integral operator I; in (2.7.2) and a modi cation of the Laplace transform (7.1.1) with k = 1 in which xt is replaced by x=t and the multiplier 1=t is added.
The transform 1F k1 in (7.5.1) was rst introduced by Erdelyi [3] in the form ;( + + 1) Z 1 (xt) F ( + + 1; + + + 1; ;xt)f(t)dt (7.12.24) 1 1 1 F 1 f (x) = ;( + + + 1) 0 with complex parameters , and . Joshi [1], [3] investigated this transform in the space Lp (R+ ) (p = 1) and proved two real inversion formulas and a representation theorem for this transform. The rst inversion relation is based on the + representation of (7.12.24) as the composition of the Kober fractional integral operator I; in (7.12.5) and the generalized Laplace transform L1;; in (3.3.3):
For Section 7.5.
F = I; L ;; :
(7.12.25) The second inversion formula contains a di erential operator which is an inverse to the Stieltjes transform (7.9.3) and has a similar form to the one given in (7.12.7) and (7.12.8) for the Meijer transform (7.2.1). Joshi used the rst inversion formula to give in a representation theorem necessary and sucient conditions for the function g(x) to have the representation in the form (7.12.24): g = 1 F 1 f with f 2 Lp (R+ ) (p = 1). In [2] Joshi showed that the Laplace transform (2.5.2) of the transform (7.12.24) yields the generalized transform 2 F 1 of the form (7.8.20): ;( + + 1);( + 1) L 2 F 1 f (x) = ;( + + + 1) 1
1
+
1
Z 1 t t 1 x x 2F1 + + 1; + 1; + + + 1; ; x f(t)dt: (7.12.26) 0
Joshi in [4] also proved certain Abelian theorems for the transform 1 F 1 in (7.12.24), and in [6], [7] gave a representation theorem for such a transform on Lorentz spaces.
256
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
Habibullah [3] and Love, Prabhakar and Kashyap [1] investigated the generalized transform 1F ; 1 in (7.5.11) with = + a ; 1, = a ; 1 and = 0, = c ; 1, respectively. They obtained the ; representations for such transforms as the compositions of the Kober fractional integral operator K; in (7.12.6) and a certain generalized Laplace transform Lk; in (3.3.3) and applied these results to nd the inversion formulas of the transforms considered. Rao [1], [3]{[7] extended the transform 1F 1 in (7.12.24) of the form (7.5.1) to a certain space of generalized functions and established analyticity, representation, inversion and uniqueness. In [8] Rao proved the Abelian theorems for such a transform and extended the results in the distributional sense (see Brychkov and Prudnikov [1, Sections 7.5] in this conection). We also mention that Wimp [1], Prabhakar [1], [2] and Habibullah [1] obtained the inversion formulas for the integral transform containing 1 F1(a; c; z) in the kernel by generalizing the Riemann{ Liouville fractional integration operators to the form 1 Z x (x ; t) ;1 F ( ; ; (x ; t)) f(t)dt ( > 0); (7.12.27) 1 1 ;( ) a and the corresponding integral transform with integration over (x; b) under certain conditions on f(t) and the integral in (7.12.27), where ;1 < a < x < b < 1. The boundedness and inversion of these operators in the space Lp (a; b) (1 5 p < 1) were given by Marichev (see Samko, Kilbas and Marichev [1, Section 37.1]). In Section 10.4 of the book, Marichev also proved the representation and boundedness theorem for such operators with a = 0 and b = 1 in Lp (R+ ) (1 5 p < 1). The modi ed transform 2 F 12 in (7.8.2) was rst considered by Swaroop [1] (1964). Using the inverse Mellin transform (see, for example, the book by Marichev [1, Theorem 25]), he gave several complex inversion formulas for this transform, proved the uniqueness theorem and the relation of integration by parts (7.8.12) also called a Parseval type property. K.C. Gupta and S.S. Mittal [1]{[3] established several theorems involving the transform 2 F 1 2 and the modi cation of the Whittaker transform (7.12.19). Kalla [2] showed that the composition of the transform (7.8.2) and a modi cation of the Varma transform (7.2.15) yields the integral transform containing the Meijer G-function (2.9.1) as a kernel. Marichev [1, Section 8.2] showed that the transform 2 F 12 can be represented in the form 2 b;1I c;b M1;c; (7.12.28) 2 F 1 = Ma;1 LMa;1 Lx ; where the operators M ; L and I;c;b are given in (3.3.11), (2.5.2) and (2.7.2), and proved the relation (7.8.12). Several authors used the compositions of the fractional integration operators of Riemann{Liouville (2.7.1), (2.7.2) and of Erdelyi{Kober type (3.3.1), (3.3.2) with the generalized Stieltjes transform (7.9.1) to obtain the inversion formulas for the generalized hypergemetric transforms. Love [3] rst ;b in (7.8.19). Prabhakar and Kashyap [1] and proved such an inversion formula for the transform 2F 1;0 1 ;c;1 in (7.8.20) and F +b;b Habibullah [3] established the inversion relations for the transforms 2 F 2;0 2 1 ;;b of1 the in (7.7.21), respectively. We also mention that Erdelyi [4] considered the transform 2F 1;0 1 form (7.8.19) in a certain space of generalized functions. Many authors investigated the integral transforms involving the Gauss hypergeometric function 2 F1 (a; b; c; z) in kernels, which generalize the fractional integration operators of Riemann{Liouville (2.7.1), (2.7.2), Kober (7.12.5), (7.12.6) and Erdelyi{Kober type (3.3.1), (3.3.2). Love [1] (1967), [2] (1967) rst considered the integral transforms of the forms for x > 0 ; c 1 Z x (x ; t)c;1 F a; b; c; 1 ; x f(t)dt; (7.12.29) I (a; b)f (x) = 2 1 1 0+ ;(c) 0 t Z x ; c t 1 c ; 1 (7.12.30) 2 I 0+ (a; b)f (x) = ;(c) 0 (x ; t) 2 F1 a; b; c; 1 ; x f(t)dt and Z 1 ; c 1 c;1 2 F1 a; b; c; 1 ; x f(t)dt; (t ; x) (7.12.31) 1 I ; (a; b)f (x) = ;(c) x t For Sections 7.7 and 7.8.
257
7.12. Bibliographical Remarks and Additional Information on Chapter 7
Z 1 t 1 c ; 1 (7.12.32) 2I ; ;(c) x (t ; x) 2 F1 a; b; c; 1 ; x f(t)dt with a; b; c 2 C (Re(c) > 0). Love proved the representations of the above transforms as compositions of two Riemann{Liouville fractional integrals (2.7.1) and (2.7.2) with power weights. These representations for the integrals (7.12.29) and (7.12.30) have the forms ;
c (a; b)f (x) =
Ic
1 0+
Ic
c;b M;a I b Ma = Mc;a;b I b Ma;c I c;b Mb ; (a; b) = I0+ 0+ 0+ 0+
(7.12.33)
b M;a I c;b Mc;b = Mb I c;b Ma;c I b Mc;b ; (a; b) = Ma I0+ (7.12.34) 0+ 0+ 0+ where M is the elementary operator (3.3.11). The representations for the integrals in (7.12.31) and c;b and I b (7.12.32) are obtained from (7.12.33) and (7.12.34) by replacing 1 I c0+ (a; b), 2 I c0+ (a; b), I0+ 0+ c c c ; b by 1I ; (a; b), 2I ; (a; b), I; and I;b , respectively. Love [1], [2] established the boundedness of the operators 1I c0+ (a; b), 2I c0+ (a; b) in the space Lq1(0; d) and 1I c; (a; b), 2I c; (a; b) in Lr1(e; 1), where 0 < d; e < 1; 1 5 p < 1, q; r 2 C , Lqp (0; d) = ff(x) : xq f(x) 2 Lp (0; d)g (7.12.35) and Lrp (e; 1) = ff(x) : xr f(x) 2 Lp (e; 1)g: (7.12.36) He applied the results obtained to nd the explicit inversion formulas for these transforms. Marichev extended the results by Love to more general weighted spaces Lqp (0; d) and Lrp (e; 1) with any p (1 5 p < 1) (see Samko, Kilbas and Marichev [1, Sections 10.1 and 35.1]). It should be noted that earlier Wimp [1] (1964) and Higgins [2] (1964) proved the inversion formulas for the transforms of the forms (7.12.31) and (7.12.32) in which the upper limit 1 is replaced by 1 (see Samko, Kilbas and Marichev [1, Section 39.2, Note 35.1]). R.K. Saxena [9] (1967) introduced the operators x;;1 Z x F ; + m; ; at t f(t)dt (7.12.37) ;(1 ; ) 0 2 1 x and x Z 1 F ; + m; ; ax t;;1f(t)dt (7.12.38) 2 1 ;(1 ; ) x t with complex parameters ; ; 2 C satisfying certain conditions and = a = 1. He gave the formulas of their Mellin transform for f(x) 2 Lp (R+ ) if 1 5 p 5 2 and for f(x) in a special space Mp if p > 2, and the relation of integration by parts being an analog of (7.7.11). Kalla and R.K. Saxena in [1] extended these results to the general transforms (7.12.37) and (7.12.38) with > 0 and complex a 2 C , and in [3] obtained the inversion formulas for these transforms (see also Kalla [10, Section 3]). We note that such a transform of the form (7.12.37) was rst studied by Erdelyi [1] (1940) while investigating the composition of the Kober operators (7.12.5) and (7.12.6) with the elementary operator R in (3.3.13): 2
0+
; Rf (x) T f (x) = I ++=2;; K= 2; with f(x) 2 L2 (R). In particular, when Re() > ;1 and n 2 N, he obtained the relation
(7.12.39)
Tn f (x) = (;1)n (Rf)(x) ;( + 1) Z 1=x (xt)=2 F (1 ; n; + n ; 1; + 1; xt)f(t)dt: + ;(n);( 2 1 + 1) 0
(7.12.40)
If we replace x by 1=x, then the second term is reduced to the transform of the form (7.12.37).
258
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
R.K. Saxena and Kumbhat [1], [3] studied the generalizations of the transforms (7.12.5) and (7.12.6) in the forms x; ; Z x(x ; t) ;1 F + ; ;; ; 1 ; t t f(t)dt (7.12.41) 2 1 ;( ) 0 x and x Z 1 (t ; x) ;1 F + ; ;; ; 1 ; x t; ; f(t)dt (7.12.42) 2 1 ;( ) x t with > 0, ; 2 C , f(x) 2 Lp (R+ ) (1 5 p 5 2). In [1] they investigated the relations between these + ; given in (7.12.5) and (7.12.6), while in [3] they transforms and the Kober transforms I; and K; established the uniqueness theorem and the inversion formulas and gave the relations between the operators in (7.12.41) and (7.12.42) and the Hankel transform H in (8.1.1) and the Laplace transform L in (2.5.2). Using the approach by Love [1], [2], McBride [1] obtained the inversion formulas for the transform Z x m (x ; tm )c;1 F a; b; c; 1 ; xm mtm;1 f(t)dt (x > 0) (7.12.43) 2 1 ;(c) tm 0 with m > 0, a; b; c 2 C (Re(c) > 0), more general than (7.12.29), and for similar generalizations of (7.12.30){(7.12.32) in spaces of generalized functions F0r; (see For Section 5.7 (Sections 5.2 and 5.3)), while Prabhakar [3] gave the inversion relation for the transform Z
d (tm ; xm )c;1
x
;(c)
2
m
F1 a; b; c; 1 ; xtm mtm;1 f(t)dt (a < x < d; m > 0)
(7.12.44)
with m > 0, a; b; c 2 C (Re(c) > 0) in the space L1 (a; b). We also mention that Braaksma and Schuitman [1] obtained the inversion relations for the integral transform of the form (7.12.32) with (t ; x)c;1 being replaced by (1 ; x=t)c;1 in certain spaces of tested and generalized functions. Saigo [1] (1979) introduced the transforms
and
; ; Z x
; ; f (x) = x I0+ ;( )
0
(x ; t) ;1 2 F1 + ; ;; ; 1 ; xt f(t)dt
1 Z 1 (t ; x) ;1 F + ; ;; ; 1 ; x t; ; f(t)dt I; ; ; f (x) = ;( ) 2 1 t
x
(7.12.45) (7.12.46)
with ; ; 2 C (Re( ) > 0), which are modi cations of the transforms (7.12.30) and (7.12.31), and investigated composition properties, the relation of integration by parts and inversion formulas in the space Lp with any 1 5 p 5 1 (see also Samko, Kilbas and Marichev [1, Section 23.2, Note 18.6] in ; ; and I ; ; . this connection). Srivastava and Saigo [1] evaluated multiplications of the operators I0+ ; Saigo and Glaeske [1] extended these and other properties of the transforms (7.12.45) and (7.12.46) to McBride spaces of tested and generalized functions F;r and F0;r . Kilbas, Repin and Saigo [1] ; ; and I ; ; as special cases of the modi ed G2 - and constructed L;r -theory for the operators I0+ ; ; ;0 G10; -transforms (6.2.5) and (6.2.4) with m = p = q = 2 and n = 0. Glaeske and Saigo [2] evaluated the Laplace transform (2.5.2) of the generlaized fractional integrals (7.12.45) and (7.12.46) and conversely these fractional integrals of the Laplace transform in F0;r . Saigo and Raina [1] obtained the images ; ; and I ; ; and gave applications to certain of some elementary functions under the operators I0+ ; statistical distributions. Saigo, R.K. Saxena and Ram [2] established the relations between the Mellin ; ; , x I ; ; and Mf, and proved the representations of the transforms (7.12.45) transform M of x I0+ 0+ ; ; and I ; ; with and (7.12.46) via the Laplace transform L and the inverse L;1. Compositions of I0+ ; the axisymmetric di erential operator of potential theory L in (5.7.16) was studied by Kilbas, Saigo and Zhuk [1].
7.12. Bibliographical Remarks and Additional Information on Chapter 7
259
Grin'ko and Kilbas [1] investigated the mapping properties of the operators 1I c0+ (a; b), 2 I c0+ (a; b), and 2I c; (a; b) given in (7.12.29){(7.12.32) in weighted Holder spaces with power weight on 1I ; the half-axis R+ , established the conditions for these operators to realize an isomorphism between two such weighted Holder spaces and gave applications to the integral transforms (7.12.45) and (7.12.46). In [2] Grin'ko and Kilbas found the conditions on the parameters a; b and c in (7.12.29){(7.12.32) sucient for all compositions of these operators with special power weights to be operators of the same form. See in this connection Samko, Kilbas and Marichev [1, Section 17.2, Note 10.1]. The authors in Saigo and Kilbas [1] proved mapping properties of the operator (7.12.45) de ned on a nite interval (0; d) (0 < d < 1) in the space of Holder functions. A series of papers was devoted to studying the inversion for special cases of the integral transform of the form (7.12.32) on a nite interval (0; 1), integration over (x; 1) being replaced by integration over (x; 1), with the Chebyshev polynomial Tn(x) and the Legendre polynomial Pk (x) in the kernels, and for modi cations of these transforms with the Legendre function P (x), the Jacobi polynomial Pn ; )(x), the Gegenbauer polynomial Ck (x) and other generalized polynomials in the kernels (see Samko, Kilbas and Marichev [1, Section 35.1 and Section 39.2, Notes 35.1 and 35.2]). Heywood and Rooney [5] investigated in the space L;r (1 5 r 5 1; 2 C ) the integral transform of the form c (a; b)
Z 1 2 ;1=2 Gk xt f(t) dtt (k 2 N0); (7.12.47) G (x) = ;( +2 1=2) x 1 ; xt2 where Gk (x) = Ck(x)=Ck(1) ( > ;1=2; 6= 0), Ck (x) is the Gegenbauer polynomial of index and order k de ned by 1 1 ; x (2) k (k 2 N; 2 C ) (7.12.48) Ck (x) = k! 2 F1 ;k; k + 2; + 2 ; 2 and Gk0(x) = Tk (x) is the Chebyshev polynomial of degree k (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, Section 10.9]). Heywood and Rooney [5] established the boundedness and the range of the transform (7.12.47) in L;r and proved its inversion formulas. We also mention that earlier the inversion relations for the integral transforms of the form (7.12.47) and similar transforms with integration over (x; d) (0 < d 5 1) were given by K.N. Srivastava [1] (1961/62), Buschman [1] (1962) and Higgins [1] (1963). We also mention Saigo and Maeda [1] who investigated on the McBride space F;r properties of integral transforms generalizing (7.12.45) and (7.12.46) and involving the Appell function F3 in (2.10.4) as the kernels.
f k
The results presented in this section were obtained by the authors in Saigo and Kilbas [5]. The generalized Stieltjes transform S ;; (7.9.1) in the particular case when = 0; = 2m and = ;m ; k + 1=2 For Section 7.9.
S0;2m;;m;k+1=2f (x) ;(2m + 1) Z 1 F 2m + 1; 1; m ; k + 3 ; ; t f(t) dt = ;(m 2 1 ; k + 3=2) 2 x x 0
(7.12.49)
with Re(m) > ;1=2 was rst considered by Arya. In [1] (1958) he proved Abelian type theorems for the transform which generalize the corresponding Abelian theorems for the Laplace transform (2.5.2) proved by Widder [1]. In [2] (1958) Arya used the Mellin transform M in (2.5.1) to establish the real inversion formula for the transform (7.12.49) in the form 1 [f(t + 0) + f(t ; 0)] 2 Z c+i1 ;(m ; k + s + 1=2) t;sMS 1 (7.12.50) = 2i 0;2m;;m;k +1=2 f (s)ds c;i1 ;(2m + s);(s);(1 ; s) under certain conditions on f(x) as well as the result that f(x) 2 Lc;1: xc;1 f(x) 2 L1 (R+ ). In [5] (1960) Arya proved the complex inversion formula for (7.12.49) on the basis of the corresponding
260
Chapter 7. Hypergeometric Type Integral Transforms on the Space L;r
complex inverse formula for the Meijer transform K in (8.9.1). Rao [2], [7] extended the transform
S0;2m;;m;k+1=2 to a certain space of generalized functions and proved a number of Abelian (an initial-
value and a nal-value) theorems for this transform. Golas [2] investigated the invertibility of the transform (7.9.1) and its generalization ;( + + 1);( + 1) 1 ;( + + + 1) x Z
1 t
t da(t); (7.12.51) 2 F1 + + 1; + 1; + + + 1; ; x x 0 where a(t) is a function of bounded variation in every nite interval. He established the real inversion formulas for these transforms via a certain integro-di erential operator. In [3] Golas investigated some other properties of the transform (7.9.1). Joshi [5] proved the complex inversion relation for the generalized Stieltjes transform S ;; in (7.9.1). Tiwari [2], [3], [6] extended this transform to a certain space of generalized functions. Tiwari and Koranne [1] proved Abelian theorems of the initial and nal value type for the transform (7.9.1) and extended the results to a certain class of generalized functions. See in this connection also Brychkov and Prudnikov [1, Section 7.11]. We also note that Glaeske and Saigo [2] investigated the left- and right-sided compositions of the generalized Stieltjes transform Z 1 f(t) dt (7.12.52) S f (x) = (x + t) 0 with the generalized fractional integrals (7.12.45) and (7.12.46) in the McBride space F0p; of generalized functions and showed that such compositions are expressed in terms of the Kampe de Feriet series (see the book by Srivastava and Karlsson [1]). Mehra and R.K. Saxena [1] (1967), by considering the transform p F p in (7.10.1), proved two theorems and derived some results in particular cases when p = 1 and p = 2. Goyal and Jain [1] studied the generalizations of the integral transforms (7.12.41) and (7.12.42) in the forms x; ; Z x (x ; t) ;1 F a ; ; a ; b ; ; b ; 1 ; t t f(t)dt (7.12.53) p q 1 p 1 p ;( ) 0 x and x Z 1 (t ; x) ;1 F a ; ; a ; b ; ; b ; h1 ; x i t; ; f(t)dt (7.12.54) p q 1 p 1 p ;( ) x t with complex parameters (Re( ) > 0); ; ai (1 5 i 5 p), bj (1 5 j 5 q) and . They showed that the composition of two transforms (7.12.53) (or (7.12.54)) with di erent parameters , , ai , bj and becomes the integral transform of the form (7.12.53) (or (7.12.54)) with p Fq being replaced by a special triple hypergeometric series. Goyal and Jain [1] also proved formally the Mellin transforms of (7.12.53) and (7.12.54) and applied the relations to give their inversion formulas and then they established certain relations of the generalized Hankel transform (8.14.62). Goyal, Jain and Gaur [1], [2] extended some of these results to more general integral transforms involving additionally in the kernels of (7.12.53) and (7.12.54) the terms with a general class of polynomials. Srivastava, Saigo and Raina [1] investigated compositions of the Laplace transform (2.5.1) with the generalized fractional integral operators (7.12.45) and (7.12.46). They proved that the compositions ; ; f and I ; ; x Lf are the transform F of the form LxI; 2 2 0+ For Section 7.10.
;( + 1);( ; + + 1) ; ;( ; + 1);( + + + 1) x
1
Z
0
2
F2 ( + 1; ; + + 1; ; + 1; + + + 1; ;xt)f(t)dt;
(7.12.55)
7.12. Bibliographical Remarks and Additional Information on Chapter 7
261
; ; f and I ; ; xLf take more complicated shapes and are represented as sums of three while Lx I0+ ; kinds of transform 2F 2. We also indicate that Prabhakar [4] studied the inversion of the integral transforms of the form (7.12.43) and (17.12.44) with 2 F1 being replaced by the con uent hypergeometric function of two variables in the space L1 (a; b). He proved that such an integral transform can be represented as the composition of two Riemann{Liouville fractional integrals (2.7.1) with power-exponential weights and applied this result to prove the inversion fomula. In [5] Prabhakar extended these assertions to more general integral transforms (in this connection see Samko, Kilbas and Marichev [1, (10.63), (10.64) and Section 17.1, Notes to x10.4]).
Chapter 8 BESSEL TYPE INTEGRAL TRANSFORMS ON THE SPACE L;r 8.1. The Hankel Transform We consider the Hankel integral transform de ned in (2.6.1) by
H f
(x) =
Z 0
1
(xt)1=2J (xt)f (t)dt (x > 0)
(8.1.1)
for Re( ) > ;1. This transform (8.1.1) is clearly de ned for a continuous function f 2 C0 with compact support on R+ for the range of parameters indicated. We note that the Hankel transform H generalizes the Fourier cosine transform 1=2 Z 1 2 cos(xt)f (t)dt (x > 0) Fc f (x) = H ;1=2f (x) =
0
(8.1.2)
and the Fourier sine transform 1=2 Z 1 2 sin(xt)f (t)dt (x > 0) Fs f (x) = H 1=2f (x) =
0
(8.1.3)
in view of the well-known formulas (Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.11(14), (15)]) J;1=2 (z ) =
2 1=2 cos z;
z
J1=2(z ) =
2 1=2 sin z:
z
First we present the results characterizing the boundedness and the representation of the Hankel transform (8.1.1) in L;r -space.
Theorem 8.1. Let 1 5 r 5 1 and let (r) be given in (3:3:9): (a) If 1 < r < 1 and (r) 5 < Re() + 3=2; then for all s = r such that s0 = 1=
and 1=s + 1=s0 = 1; the operator H belongs to [L;r ; L1;;s ] and is a one-to-one transform from L;r onto L1;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:1:1) for Re(s) = 1 ; is given by 1 + s + 1 ; 2 Mf (1 ; s): (8.1.4) MH f (s) = 2s;1=2 21 3 ; 2 ;s+ 2 263
264
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(b) If 1 5 5 Re() + 3=2; then H 2 [L; ; L ;;1 ]. If 1 < < Re() + 3=2; then for 1
1
all r (1 5 r 5 1) H 2 [L;1 ; L1;;r ]. (c) If f 2 L;r and g 2 L;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r +1=s = 1 and max[ (r); (s)] 5 < Re( ) + 3=2; then the following relation holds: 1
Z 0
f (x) H g (x)dx =
1
Z
(x)g (x)dx:
H f
0
(8.1.5)
(d) If f 2 L;r ; where 1 < r < 1 and (r) 5 < Re() + 3=2; then for almost all x > 0
H f
d +1=2 x (x) = x;(+1=2) dx
1
Z
0
(xt)1=2J+1 (xt)f (t) dtt :
(8.1.6)
Proof. The assertion (a) coincides with those in Theorem 8.50(a),(b) which will be proved
in Section 8.12. To prove (b) we rst note that by (2.6.2) and Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.13(3)] the asymptotic behavior of J (z ) near zero and in nity have the forms 2; z (z ! 0); (8.1.7) J (z ) ;( + 1) 2 1=2 cos z ; 1 + 1 (z ! 1): (8.1.8) J (z ) z 2 2 Hence there is a constant K such that, for all x > 0;
jJ (x)j 5 K x; = ; if 1 5 5 Re( ) + 3=2. Then for f 2 C and 1 5 5 Re( ) + 3=2; we have 3 2
0
H f
(x) 5
1
Z 0
(xt)1=2jJ (xt)jjf (t)jdt 5 K x ;1
1 ;1 t jf (t)jdt = K x ;1 kf k;1
Z 0
and i
h ess sup x1; H f (x) =
H f
1;;1 5 K kf k;1 :
x2R
Thus H can be extended to L;1 for 1 5 5 Re( ) + 3=2; and H
2 [L; ; L ;;1 ] 1
and H is clearly given in (8.1.1) on L;1 . If 1 < < Re( ) + 3=2; we have Z 0
1 1; dx x H f (x)
x
5 =
Z 0 Z 0
1 ; Z 1 x dx (xt)1=2jJ (xt)jjf (t)jdt
M=
1
Z 0
0
Z 1 1 1=2 x1=2; jJ (xt)jdx t jf (t)jdt
= M where
(8.1.9)
1
0
1 ;1 t jf (t)jdt;
Z 0
x1=2; jJ (x)jdx < 1;
(8.1.10)
265
8.1. The Hankel Transform
if and only if 1 < < Re( ) + 3=2 in view of (8.1.7) and (8.1.8). Hence
2 [L; ; L ;; ]:
H
1
1
(8.1.11)
1
By the interpolation of Banach spaces (see Stein [1, Theorem 2]), if 1 < < Re( ) + 3=2 and 1 5 r 5 1, we obtain H 2 [L;1 ; L1;;r ], which completes the proof of the assertion (b). To prove (c) we note that for f; g 2 C0; the relation (8.1.5) is proved directly by using Fubini's theorem. Hence, since C0 is dense in L;r and L;s (see Rooney [1, Lemma 2.2]), (8.1.5) will be true if we show that both sides of (8.1.5) represent bounded bilinear functionals on L;r L;s . Now the assumption 1=r +1=s = 1 implies r0 = s and the fact that 1=r 5 (r) 5 yields (r0)0 = r = 1=: Thus the assumption (a) deduces H 2 [L;s ; L1;;r ]. Applying the Holder inequality (4.1.13) we have 0
1
Z
0
f (x) H g (x)dx 5
1 jx f (x)j x1; H g (x) dx
Z
x
0
5 K kf k;r
H g
;;r
1
0
5 K kf k;r kgk;s;
where K is a bound for H as an element of [L;s ; L1;;r ]. So the left-hand side of (8.1.5) is a bounded bilinear functional on L;r L;s as the right-hand side of (8.1.5) is by a similar calculation, which shows (c). To prove (d) we need in the function of the form (3.5.5): 0
8 <
g;x(t) = :
t+1=2 ; if 0 < t < x; 0; if t > x
(8.1.12)
and the function h;x (t) = x+1 t;1=2 J+1 (xt);
(8.1.13)
for which we prove the following auxiliary result.
Lemma 8.1. Let 1 < r < 1: The following assertions hold: (a) g;x 2 L;r if and only if > ;Re() ; 1=2: (b) If Re() > ;3=2; then h;x 2 L;r if and only if ;Re() ; 1=2 < < 1: (c) If Re() > ;1; then H g;x = h;x
(8.1.14)
H h;x = g;x :
(8.1.15)
and
Proof. According to (3.1.3) kg;xk;r =
x
Z 0
if and only if > ;Re( ) ; 1=2; which proves (a).
=r
1
tr( +Re()+1=2);1dt
< 1;
266
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Since from (8.1.7), if Re( ) > ;2 h;x (t)
1
2+1 ;( + 2) x
2 +2
t+1=2 (t ! +0)
(8.1.16)
and from (8.1.8) 1=2 1 1 2 +1=2 ;1 x t cos xt ; + (t ! 1); h;x (t) 2 2 then h;x 2 L;r ; if and only if
Z 0
tr( ++1=2);1 dt < 1;
Z
(8.1.17)
1 r( ;1);1 t dt < 1
R
for some positive and R; and thus, for ;Re( ) ; 1=2 < < 1 guaranteed by the assumption Re( ) > ;3=2; (b) is proved. Putting = 1=2; r = 2 in (a), we have g;x 2 L1=2;2 = L2 (R+ ) if Re( ) > ;1. By noting that d Z ut 1=2 1 1=2 v J (v )dv; (ut) J (ut) =
u dt
0
when Re( ) > ;1=2, and by taking into account (8.1.12) and the relation Z
z +1 J (z )dz = z +1 J+1 (z )
(8.1.18)
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.7(1)]), we have
H g;x
1
du Z ut 1=2 d Z x ;1=2 Z ut 1=2 v J (v )dv = u du v J (v )dv u 0 dt 0 0 0 d Z t 1=2 Z x +1 d Z x +1 Z t 1=2 = dt u du v J (uv )dv = dt v dv u J (uv )du 0 0 0 0
(t) = dtd
Z
= t1=2
Z
x
0
g;x(u)
u+1 J (ut)du = t;(+3=2)
Z
xt 0
u+1 J (u)du = x+1 t;1=2 J+1 (xt)
= h;x (t): It follows from the Titchmarsh theorem f (x) =
dt d Z1 k(xt)g (t) ; dx 0 t
g (x) =
d Z1 dt k(xt)f (t) dx 0 t
(8.1.19)
in L2(R+ ) (see Titchmarsh [3, Theorem 129]) and (8.1.4), that on L1=2;2 the operator H 2 is an identity: H 2 = I . Since h;x 2 L1=2;2 = L2(R+ ) by the result of Theorem 8.1(a), H h;x
= H 2 g;x = g;x;
which completes the proof of Lemma 8.1.
267
8.1. The Hankel Transform
Now we can prove the assertion (d) of Theorem 8.1. By Lemma 8.1(a), g;x 2 L;r : Applying (8.1.12), Theorem 8.1(c), (8.1.14) and (8.1.13), we have for x > 0 0
x
Z 0
t+1=2 H f (t)dt =
=
1
Z 0 Z
1
g;x(t) H f (t)dt =
1
Z 0
0
h;x (t)f (t)dt = x+1=2
Z
H g;x
1 0
(t)f (t)dt
(xt)1=2J+1 (xt)f (t) dtt
and the result in (8.1.6) follows on di erentiating. Thus Theorem 8.1 is proved. Next we present the results characterizing the range of the Hankel transform (8.1.1) in the space L;r . First we indicate the constancy of the range of H : H (L;r ) = H (L;r );
(8.1.20)
if 1 < r < 1; (r) 5 < min[Re( ); Re( )]+3=2: This relation for real and was proved by Rooney [3, Theorem 1] by using a technique based on Mellin multipliers, and can be clearly extended to complex and . To give a complete description of H (L;r ) we prove the representation of H f in terms of the shift operator M and the Erdelyi{Kober operator 2x;2( +) Z x (x2 ; t2 ) ;1t2+1 f (t)dt ( ; 2 C ; Re( ) > 0) ;( ) 0 (see Samko, Kilbas and Marichev [1, (18.8)]) with
I ; f (x) =
I0; f (x) = f (x);
(8.1.21) (8.1.22)
where (8.1.21) is the special case of the operator I0+; ; de ned in (3.3.1) as I ; = I0+;2; .
Lemma 8.2. Let 1 < r < 1; (r) 5 < Re() + 3=2; where = (r) is given in (3:3:9):
If f 2 L;r ; then the representation H f
= 2 ; M ; I ; ;(; + ;1=2)=2 H ; + M ; f
(8.1.23)
holds.
Proof. By putting = ; + and = ; ; we rewrite (8.1.23) in the simpler form H + f
= 2; M I ;( ;1=2)=2H M f;
(8.1.24)
which we are going to prove. Let f 2 C0. Note that Re( ) > ;1 and = 0 from the assumptions. The result is obvious if = 0 in view of (8.1.22). Let > 0. Using the relation 1 x;( + ) t Z x (x2 ; u2) ;1 u +1J (tu)du (8.1.25) J + (xt) = ;1 2 ;( ) 0 in Prudnikov, Brychkov and Marichev [2, (2.12.4.6)] and Fubini's theorem, we have
H + f
(x) =
Z 0
1
(xt)1=2J + (xt)f (t)dt
268
Chapter 8. Bessel Type Integral Transforms on the Space L;r Z 1 Z x 1 1=2;( + ) +1=2 t f (t)dt (x2 ; u2 ) ;1u +1 J (tu)du = 2 ;1;( ) x 0 0 Z x Z 1 1 1=2;( + ) 2 2 ;1 +1=2 (x ; u ) u du (tu)1=2J (tu)t f (t)dt = 2 ;1;( ) x 0 0
= 2; M I ;( ;1=2)=2H M f (x) and (8.1.24) is proved for f 2 C0. Due to Rooney [2, Lemma 2.2], C0 is dense in L;r and by Theorem 8.1(a), we have H 2 [L;r ; L1;;r ]. Thus to complete the proof we must show that M I ;( ;1=2)=2H M 2 [L;r ; L1;;r ]:
(8.1.26)
But by Lemma 3.1(i) M maps L;r isometrically onto L ; ;r = L ;r and by Theorem 8.1(a) H maps L ;r boundedly into L1; ;r under < Re( ) + 3=2: Then according to Theorem 3.2(a) I ;( ;1=2)=2 maps L1; ;r boundedly into itself, if 1 ; < Re( ) + 3=2 which is valid from the assumption. Finally M maps L1; ;r isometrically onto L1; ; ;r = L1;;r ; and thus the result in (8.1.24) follows. This completes the proof of Lemma 8.2. Now we are ready to prove the range of the Hankel transform (8.1.1) in terms of the shift operator M in (3.3.11), the Erdelyi{Kober operator I ; in (8.1.21) and the cosine transform Fc in (8.1.2).
Theorem 8.2. Let 1 < r < 1 and 5 < Re() + 3=2; where = (r) is given in
(3:3:9): Then there holds
H (L;r ) =
M ; I ; ;;1=2 Fc (L ;r ):
(8.1.27)
In particular; if r = 2 and 1=2 5 < Re( ) + 3=2; then H (L;2 ) =
M ;1=2 I ;1=2;;1=2Fc
L2 (R+ ) :
(8.1.28)
Proof. Let = ; ; 1=2: Then +3=2 = ; +1 > ; since < 1: Hence by (8.1.20), H (L;r ) = H (L;r ) = H ; ;1=2 (L;r ):
(8.1.29)
According to Lemma 8.2 and (8.1.2), if f 2 L;r ; we have H ; ;1=2 f
= 2 ; M ; I ; ;;1=2 H ;1=2 M ; f = 2 ; M ; I ; ;;1=2 Fc M ; f:
(8.1.30)
Let g 2 H (L;r ): Then by (8.1.29) and (8.1.30) there exists f 2 L;r such that g = 2 ; M ; I ; ;;1=2 Fc M ; f:
Since M ; f 2 L ;r , g 2 (M ; I ; ;;1=2 Fc )(L ;r ) which means that H (L;r )
M ; I ; ;;1=2 Fc (L ;r ):
(8.1.31)
269
8.1. The Hankel Transform
Conversely, if g 2 M ; I ; ;;1=2 Fc (L ;r ); there exists f 2 L ;r such that g = M ; I ; ;;1=2 Fc f . Let f1 = M ; f . Then f1 2 L;r and g = 2 ; H ; ;1=2 f1 from (8.1.30), which imply that g 2 H ; ;1=2 (L;r ). Thus by virtue of (8.1.29) we nd
M ; I ; ;;1=2 Fc (L ;r ) H (L;r ):
(8.1.32)
From (8.1.31) and (8.1.32) we obtain (8.1.27), which completes the proof of Theorem 8.2. Theorem 8.1(c) and Lemma 8.1 allow us to nd the inversion formula for the Hankel transform (8.1.1) in the space L;r .
Theorem 8.3. Let 1 < r < 1 and (r) 5 < min[1; Re() + 3=2]: If f 2 L;r ; then the
inversion relation
f (x) = x;(+1=2)
dt d +1=2 Z 1 1=2 x ( xt) J+1 (xt) H f (t) dx t 0
(8.1.33)
holds for almost all x > 0: Proof. Since Re() > ;1 and ;Re() ; 1=2 < 1=2 5 (r) 5 < 1; Lemma 8.1(b) yields that h;x de ned in (8.1.13) is in the space L;r . Then by Theorem 8.1(c) and Lemma 8.1(c) we have 0
x+1=2
Z
=
1
0 Z
(xt)1=2J+1 (xt)
1 0
H h;x
H f
(t) dtt =
(t)f (t)dt =
x
Z 0
Z 0
1
h;x (t) H f (t)dt
t+1=2 f (t)dt
and the result in (8.1.33) follows on di erentiating.
Corollary 8.3.1. If 1 < r < 1 and (r) 5 < Re() + 3=2, then the transform H is
one-to-one on L;r . Proof. Let f 2 L;r and H f = 0. If (r) 5 < min[1; Re() + 3=2], then f = 0 according to Theorem 8.3. When (r) 5 < Re( ) + 3=2, then by Lemma 8.2 M ; I ; ;(; + ;1=2)=2 H ; + M ; f = 0
and hence H ; + M ; f = 0 taking into account the isomorphism of the operator M and I ; (see Lemma 3.1(i) and Rooney [1, Lemma 3.4]). Thus M ; f 2 L ;r . If we note < 1 and < Re( ) ; + + 3=2, then by the previous result with being replaced by ; + , we have M ; f = 0 and f = 0. This result will be used in Section 8.7 while studying the transform Y .
Remark 8.1. The right-hand sides of (8.1.6) and (8.1.33) are the same except that in
(8.1.33) f is replaced by H f which means formally H ; 1 = H or H 2 is an identity: H 2 = I . However, except for the case L1=2;2 = L2(R+ ) this is purely formal. If f 2 L;r (1 < r < 1) and (r) 5 < Re( ) + 3=2; then H f 2 L1;;r and thus for H 2 to be de ned we require that (r) 5 1 ; < Re( ) + 3=2. But since (r) = 1=2 with the equality only if r = 2; then
270
Chapter 8. Bessel Type Integral Transforms on the Space L;r
1 ; 5 1=2 5 (r) with the equality only if r = 2; and thus = 1=2 and r = 2. In Theorem 8.3 we found the inversion for the Hankel transform H on L;r , but with the restriction that < 1. The result below is the exception of this restriction.
Theorem 8.4. Let 1 < r < 1 and (r) 5 < Re()+3=2; or r = 1 and 1 5 5 Re()+ 3=2 where (r) is given in (3:3:9): If we choose the integer l > and if f 2 L;r ; then the inversion relation d l +l;1=2 Z 1 1=2 1 ; +1=2 x (xt) J (xt) H f (t) dt (8.1.34) f (x) = x x dx
+l
0
tl
holds for almost all x > 0; Proof. This is proved similarly to Theorem 8.3 on the basis of Theorem 8.1(c) and Lemma 8.1 if we choose the function h;x (t) = x+l t;l+1=2 J+l (xt) (l 2 N) (8.1.35) instead of that in (8.1.13) and take into account Theorem 8.1(b) and the property 1 d l [z J (z )] = z ;l J (z ) (8.1.36) ;l
z dz
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2(52)]).
8.2. Fourier Cosine and Sine Transforms We consider the Fourier cosine and sine transforms Fc and Fs de ned in (8.1.2) and (8.1.3). As indicated in Section 8.1, these transforms are particular cases of the Hankel transform (8.1.1) when = ;1=2 and = 1=2; respectively. Therefore from the results in Section 8.1 we obtain the L;r -theory of them. The boundedness and the representation of the cosine and sine transforms in the space L;r follow from Theorem 8.1.
Theorem 8.5. Let 1 5 r < 1 and let (r) be given in (3:3:9): (a) If 1 < r < 1 and (r) 5 < 1; then for all s = r such that
s0 = 1= and 1=s +1=s0 = 1; the operator Fc belongs to [L;r ; L1;;s ] and is a one-to-one transform from L;r onto L1;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:1:2) for Re(s) = 1 ;
is given by
MFc f (s) = 2s;1=2
s
; 2 Mf (1 ; s): ; 1 ;2 s
(8.2.1)
(b) Fc 2 [L (R ); L1(R )]. (c) If f 2 L;r and g 2 L;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r +1=s = 1 1
+
+
and max[ (r); (s)] 5 < 1; then the following relation holds: Z 0
1
f (x) Fc g (x)dx =
1
Z 0
Fc f (x)g (x)dx:
(8.2.2)
271
8.2. Fourier Cosine and Sine Transforms
(d) If f 2 L;r ; where 1 < r < 1 and (r) 5 < 1; then for almost all x > 0;
Fc f (x) =
Z dt d 1 ( xt)1=2J1=2 (xt)f (t) dx 0 t
1=2 Z 1 d dt = 2 sin( xt)f (t) : dx 0 t
(8.2.3)
Theorem 8.6. Let 1 5 r < 1 and let (r) be given in (3:3:9): (a) If 1 < r < 1 and (r) 5 < 2; then for all s = r such that
s0 = 1= and 0 1=s +1=s = 1; the operator Fs belongs to [L;r ; L1;;s ] and is a one-to-one transform from L;r onto L1;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:1:3) for Re(s) = 1 ;
is given by
1 + s ; 2 Mf (1 ; s): (8.2.4) MFs f (s) = 2s;1=2 2 ; ; 2s (b) If 1 5 5 2; then Fs 2 [L;1; L1;;1 ]. If 1 < < 2; then for all r (1 5 r 5 1); Fs 2 [L;1 ; L1;;r ]. (c) If f 2 L;r and g 2 L;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r +1=s = 1 and max[ (r); (s)] 5 < 2; then the following relation holds:
Z1
0
f (x) Fs g (x)dx =
Z 1
0
Fs f (x)g (x)dx:
(8.2.5)
(d) If f 2 L;r ; where 1 < r < 1 and (r) 5 < 2; then for almost all x > 0;
Fs f (x) =
Z1 d x (xt)1=2J3=2(xt)f (t) dtt : x dx 0
1
(8.2.6)
Theorem 8.2 gives the range of the Fourier sine transform in the space L;r .
Theorem 8.7. Let 1 < r < 1 and (r) be given in (3:3:9): If 5 < 2; then
Fs (L;r ) = M ; I ; ;;1=2 Fc (L ;r );
(8.2.7)
where I ; is the Erdelyi{Kober operator (8:1:21). In particular if r = 2 and 1=2 5 < 2;
Fs (L;2 ) = M ;1=2 I ;1=2;;1=2Fc
L2 (R+ ) :
(8.2.8)
From Theorem 8.4 we come to the inversion formulas for the Fourier cosine and sine transforms in the space L;r
Theorem 8.8. Let 1 < r < 1; and let l be an integer such that l > . (a) Let (r) 5 < 1; or r = 1 and = 1. If f 2 L;r ; then the inversion relation Z dt d l l;1 1 ( xt)1=2Jl;1=2 (xt) Fc f (t) l x f (x) = x x dx t 0
1
(8.2.9)
272
Chapter 8. Bessel Type Integral Transforms on the Space L;r
holds for almost all x > 0: In particular; when l = 1;
Z dt d 1 ( xt)1=2J1=2(xt) Fc f (t) dx 0 t 1=2 Z dt d 1 sin( xt) Fc f (t) : = 2 dx 0 t
f (x) =
(8.2.10)
(b) Let (r) 5 < 2; or r = 1 and 1 5 5 2. If f 2 L;r ; then the inversion relation Z dt d l l 1 1 x ( xt)1=2Jl+1=2 (xt) Fs f (t) l f (x) = x dx t
0
holds for almost all x > 0: In particular; when l = 1; 1 d x Z 1 (xt)1=2J (xt)F f (t) dt : f (x) = x dx
3=2
0
s
t
(8.2.11) (8.2.12)
Remark 8.2. It follows from Theorems 8.5{8.8 that the range of the parameter ; for
which the L;r -theory of the Fourier cosine and sine transforms (8.1.2) and (8.1.3) is valid, is wider for the former than for the latter. We also note that direct di erentiation of the right sides in (8.2.10) and (8.2.12), by using (8.1.36) with l = 1 for the latter, yields the known inversion formulas 1=2 Z 1 2 cos(xt) F f (t)dt (8.2.13) f (x) =
and f (x) =
1=2 Z 1 2
c
0
0
sin(xt) Fs f (t)dt
(8.2.14)
for the cosine and sine transforms (8.1.2) and (8.1.3), respectively.
8.3. Even and Odd Hilbert Transforms
Let us consider the even and odd Hilbert integral transforms H + and H ; de ned by and
H + = ;FsFc
(8.3.1)
H ; = FcFs;
(8.3.2)
where Fc and Fs are the Fourier cosine and Fourier sine transforms de ned in (8.1.2) and (8.1.3), respectively. Since Fc ; Fs 2 [L1=2;2]; H + and H ; also belong to [L1=2;2]. The fact that F2c = F2s = I
(8.3.3)
273
8.3. Even and Odd Hilbert Transforms
on L1=2;2 = L2(R+ ) implies the relations
H H ; = H ;H +
+
= ;I
(8.3.4)
on L2 (R+ ), where I is an identical operator. Applying Theorem 8.1 twice, once with = ;1=2 and once with = 1=2; it follows that if f; g 2 L1=2;2; then the relation of integration by parts (8.1.5) takes the forms 1
Z
H
0
and
1
Z 0
f (t)g (t)dt = ;
H ;f
(t)g (t)dt = ;
1
Z
+
0
Z 0
1
H ; g (t)dt
(8.3.5)
H
(8.3.6)
f (t)
f (t)
+
g (t)dt:
Taking g to be the characteristic function ( 1; if 0 < t < x; x (t) = (8.3.7) 0; if t > x; we obtain, by virtue of the simple equality Z 1 1 fcos ax ; cos bxgdx = log b (a; b > 0) x a 0 (see Prudnikov, Brychkov and Marichev [1, (2.5.29.16)]), the integral representations
and
Z 2 H + f (x) = ; 1 dxd 01 log 1 ; xt2 f (t)dt
H;f
d Z 1 log t ; x f (t)dt (x) = ; 1 dx t + x
0
(8.3.8) (8.3.9)
for almost all x > 0. Comparing (8.3.8) and (8.3.9) with Theorem 90 in Titchmarsh [3], it is evident that H ; is the restriction on R+ of the Hilbert transform of even functions, while H + is the restriction on R+ of the Hilbert transform of odd functions; hence the names, even and odd Hilbert transforms are given to them. It follow from (8.3.8) and (8.3.9) that for suitable functions f and almost all x > 0, H + f and H ; f can be represented in the forms Z (8.3.10) H +f (x) = 2x p:v: 01 t2 ;1 x2 f (t)dt and Z (8.3.11) H ; f (x) = 2 p:v: 01 t2 ;t x2 f (t)dt; where p.v. denotes the Cauchy principal value of the integral at t = x. The action of the Mellin transform on H + and H ; on L1=2;2 is directly computed from (8.1.4). This yields that, if f 2 L1=2;2; then for Re(s) = 1=2 we have s Mf (s) (8.3.12) MH + f (s) = ; tan 2
274
Chapter 8. Bessel Type Integral Transforms on the Space L;r
and
s Mf (s): (8.3.13) MH ; f (s) = cot 2 According to (8.3.1) and (8.3.2) and Theorems 8.5 and 8.6, H + and H ; can be extended to L;r for 1 < r < 1. The properties of these operators on this space are given in the following result.
Theorem 8.9. (a) Let 1 < r < 1 and ;1 < < 1. The transform H belongs to [L;r ]: When 6= 0; H maps L;r one-to-one onto itself. For f 2 L;r the representations (8:3:8) and (8:3:10) +
+
hold. If 1 < r 5 2 and f 2 L;r ; the Mellin transform of H + for Re(s) = is given in (8:3:12): (b) Let 1 < r < 1 and 0 < < 2: The operator H ; belongs to [L;r ]: When 6= 1; H ; maps L;r one-to-one onto itself. For f 2 L;r the representations (8:3:9) and (8:3:11) hold. If 1 < r 5 2 and f 2 L;r ; the Mellin transform of H ; for Re(s) = is given in (8:3:13): (c) Let 1 < r < 1; f 2 L;r and g 2 L1;;r . If ;1 < < 1; then the formula of integration by parts (8:3:5) holds; while when 0 < < 2; (8:3:6) holds. (d) Let 1 < r < 1: On L;r with 0 < < 1; the formula (8:3:4) holds. Further; the relation 0
H
+
= M1H ; M;1
(8.3.14)
holds for ;1 < < 1; while the relation
H ; = M; H 1
+
M1
(8.3.15)
holds for 0 < < 2; where the shift operator M is given in (3.3.11). Proof. The function m(s) = ; tan(s=2) in (8.3.12) belongs to the class A (see De nition 3.2) with (m) = ;1 and (m) = 1. In fact, elementary arguments show that (a) m(s) is analytic in ;1 < Re(s) < 1; (b) m(s) is bounded in every closed substrip 1 5 Re(s) 5 2 ; where ;1 < 1 5 2 < 1; (c) for ;1 < < 1; 2 0 jm ( + it)j = 2 sec 2 ( + it) = O x1 (jtj ! 1): Thus Theorem 3.1 yields that, since (8.3.12) holds on L1=2;2; the operator H + 2 [L;r ] for ;1 < < 1; and if f 2 L;r with 1 < r < 1 and ;1 < < 1; then (8.3.12) holds for Re(s) = . From 1 = ; cot s = ; tan (1 ; s) = m(1 ; s); m(s) 2 2 we have 1=m 2 A with (1=m) = 0 and (1=m) = 2; which imply, by Theorem 3.1, that H + maps L;r one-to-one onto itself if 0 < < 1: Further, we have 1=m(s) = m(;1 ; s) and hence also 1=m 2 A with (1=m) = ;2 and (1=m) = 0. So, again by Theorem 3.1, H + maps L;r one-to-one onto itself if ;1 < < 0: The representation (8.3.10) follows from (8.3.8) by
275
8.3. Even and Odd Hilbert Transforms
di erentiating, while the representation (8.3.8) follow from the relation (8.3.5) by taking g as the characteristic function (8.3.7). Thus once (8.3.5) is proved for f 2 L;r and g 2 L;r , (a) is proved. The proof of the statement (b) is exactly similar. The relations of integration by parts (8.3.5) and (8.3.6) follow from the fact that these formulas hold for f 2 L1=2;2; g 2 L1=2;2 and that both sides of them represent bounded bilinear functionals on L;r L1;;r : The formula (8.3.4) holds since it is valid on L1=2;2 and its both sides represent bounded operators on L;r . The equalities (8.3.14) and (8.3.15) follow on L;2 on taking the Mellin transform, and then on their respective L;r ; since both sides of (8.3.14) and (8.3.15) represent bounded operators on those spaces. This completes the proof of Theorem 8.9. 0
0
According to (8.3.1) and (8.3.2), the inversion formulas for the even and odd Hilbert transforms H + and H ; can be obtained from that for the Fourier cosine transform Fc and the Fourier sine transform Fs given in Theorem 8.8.
Theorem 8.10. Let m and l be integers such that m > 1=2 and l > 1=2. Let Fcm and (
Fsl
()
)
be given by
m Z 1 d 1 m ; 1 (xt)1=2Jm;1=2(xt) Fc f (t) tdtm ; (x) = x x dx x 0 Z 1 d l xl 1 (xt)1=2J (xt)F f (t) dt : F(sl) f (x) = s l+1=2 x dx tl 0 (a) If f 2 L2(R+ ); then the inversion relation
Fcm) f (
f (x) = ; F(cm)F(sl)H + f (x)
(8.3.16) (8.3.17) (8.3.18)
holds for almost all x > 0. (b) If f 2 L2(R+ ); then the inversion relation
f (x) = F(sl)F(cm) H ; f (x)
(8.3.19)
holds for almost all x > 0. Proof. Let f 2 L;r with 1 < r < 1, 2 R and let (r) be given by (3.3.9). According to (8.3.1) Fs (Fs f ) = ;H+ f:
If (r) 5 < 1, then by Theorem 8.5(a) Fs f 2 L1;;r . Applying Theorem 8.8(b) with being replaced by 1 ; we have Fs f = ;F(sl) H+ f;
provided that (r) 5 1 ; < 2 and l is an integer such that l > 1 ; . Similarly, if (r) 5 < 1 and m is an integer such that m > , then by Theorem 8.8(a) and the last relation we obtain
f = ;F(cm) F(sl)H+f;
276
Chapter 8. Bessel Type Integral Transforms on the Space L;r
and (8.3.18) is proved. From the above conditions this relation holds only when (r) 5 5 1 ; (r). In accordance with (3.3.9) such a fact is possible in the case r = 2 which yields = (2) = 1=2. Hence the relation (8.3.18) holds for f 2 L1=2;2 L2(R+). This completes the proof of (a). The assertion (b) is proved similarly. Theorem 8.10 give the inversion formulas for the even and odd Hankel transforms de ned by (8.3.1) and (8.3.2) in the space L2(R+ ). Another inversion formula for these transforms given in (8.3.10) and (8.3.11), was proved in the space L;r by Heywood and Rooney [3, Theorem 4.1].
Theorem 8.11. Let 1 < r < 1. (a) If ;1 < < 0 and f 2 L;r ; then Z 1 1 t 2 ; H f (t)dt: f (x) = p:v: + t t2 ; x2 0 (b) If 1 < < 2 and f 2 L;r ; then Z 1 x 1 2 x ; H f (t)dt: f (x) = p:v: ; x2 ; t2 x 0
(8.3.20)
(8.3.21)
8.4. The Extended Hankel Transform We consider the so-called extended Hankel integral transform de ned by
H ;l f
(x) =
Z
1
0
(xt)1=2J;l (xt)f (t)dt
(8.4.1)
for Re( ) > ;1; a non-negative integer l and x 2 R+ . The function J;k (z ) called a \cut" Bessel function,
J;l (z ) =
1
(;1)k (z=2)2k+ : k=l ;( + k + 1)k!
X
(8.4.2)
The extended Hankel transform H ;l is de ned for f 2 C0 and for 2 C ( 6= ;1; ;3; ) and for the least non-negative integer l = l such that Re( ) + 2l > ;1. It is directly proved that if f 2 L1=2;2 = L2 (R+ ); then for Re(s) = 1=2 the Mellin transform of (8.4.1) is given by 1 1 +s+ 2 ; : (8.4.3) MH ;l f (s) = G (s) Mf (1 ; s); G (s) = 2s;1=2 21 ; 2 ; s + 23 It is easy to see that if 1 < r 5 2 and (r) 5 < Re( )+2l +3=2; (r) being given in (3.3.9), and if f 2 L;r ; then (8.4.3) is valid for Re(s) = 1 ; ; because both sides of (8.4.3) represent the bounded linear transforms of L;r into Lr (R+ ): 0
277
8.4. The Extended Hankel Transform
The boundedness and the representation for the extended Hankel transform (8.4.1) is given by the following result.
Theorem 8.12. Let 1 5 r 5 1 and let (r) be given by (3:3:9): (a) If 1 < r < 1 and (r) 5 < Re() + 2l + 3=2; then for all s = r such that s0 = 1=
and 1=s + 1=s0 = 1; the operator H ;l belongs to [L;r ; L1;;s ]. If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:4:1) for (Re(s) = 1 ; is given in (8:4:3). (b) If 1 5 5 Re() + 2l + 3=2; then H ;l 2 [L;1; L1;;1 ]. If 1 < < Re() + 2l + 3=2; then for all r; 1 5 r < 1; H ;l 2 [L;1 ; L1;;r ]. (c) If f 2 L;r and g 2 L;r ; where 1 < r < 1 and (r) 5 < Re() + 2l + 3=2; then the following relation holds: 0
Z1
0
f (x)
H ;l g (x)dx =
Z1
0
g (x)
H ;l f (x)dx:
(8.4.4)
(d) If f 2 L;r ; where 1 < r < 1; (r) 5 < Re() + 2l + 3=2; then for almost all x > 0;
;1=2
H ;lf (x) = ;x
Z d 1=2; 1 x (xt)1=2J;1;l+1 (xt)f (t) dtt : dx 0
(8.4.5)
Proof. The asssertions (a){(c) are proved similarly to those in Theorem 8.1(a){(c). As for (d) it is proved similarly to that in Theorem 8.1(d), using the following statement similar to Lemma 8.1 in Section 8.1. Lemma 8.3. For x > 0 let
8 < t1=2; ; g;x(t) = : 0;
if 0 < t < x; if t > x:
(8.4.6)
If either 1 5 r < 1 and > Re( ) ; 1=2; or if r = 1 and = ; Re( ) ; 1=2; then the function g;x(t) 2 L;r and its extended Hankel transform is given by
H ;l g;x (t) = ;x1; t;1=2 J;1;l+1 (xt):
(8.4.7)
The inversion theory of the extended Hankel operator H ;l on L;r is di erent according as is less than, greater than, or equal to ;Re( ) ; 2l + 3=2: The rst two cases are given by the following statements.
Theorem 8.13 Let 1 5 r < 1 and (r) 5 < Re()+2l+3=2; and < ;Re();2l+3=2: If f 2 L;r ; then for almost all x > 0; the following inversion relation holds: f (x) = ;x+1=2
Z dt d 3 5=2; 1 ( xt)1=2J;3;l+3 (xt) H ;l f (t) 3 : x x dx t 0
1
If; in addition; < 2; then for almost all x > 0; 2 Z1 3 =2; +1=2 1 d (xt)1=2J x f (x) = x x dx
0
;2;l+2
(xt) H ;lf (t) dt ; t2
(8.4.8) (8.4.9)
278
Chapter 8. Bessel Type Integral Transforms on the Space L;r
while; if in addition; < 1; then for almost all x > 0 f (x) = ;x;1=2
Z dt d 1=2; 1 x ( xt)1=2J;1;l+1 (xt) H ;l f (t) : dx t 0
Theorem 8.14. Let 1 5 r < 1 and (r) 5
(8.4.10)
Re( ) + 2l + 3=2; and > ;Re( ) ; 2l + 3=2: If f 2 L;r ; then for almost all x > 0 the following inversion relation holds: 3 Z1 5 =2; +1=2 1 d x (xt)1=2J (xt) H f (t) dt : (8.4.11) f (x) = ;x x dx
0
<
;3;l+2
If; in addition; < 2; then for almost all x > 0 1 d 2 x3=2; Z 1 (xt)1=2J f (x) = x+1=2 x dx
0
t3
;l
dt ;2;l+1 (xt) H ;lf (t) 2 ; t
(8.4.12)
while; if in addition; < 1; then for almost all x > 0 ;1=2
f (x) = ;x
Z dt d 1=2; 1 x ( xt)1=2J;1;l (xt) H ;lf (t) : dx t 0
(8.4.13)
The proofs of Theorems 8.13 and 8.14 are based on the relation (8.4.4) in Theorem 8.12 and the auxiliary results for the three integrals I1; I2 and I3 de ned below for x > 0 and being taken in the principal value sense at in nity. These integrals are the inverse Mellin transforms for the function G (s) in (8.4.3).
Lemma 8.4. There hold the following statements. (i) If < 3=2; then
1 Z +i1 G (s) x;s ds = ;x;1=2 J ;1;l+1 (x) 2i ;i1 3 ; ; s 2 for ;Re( ) ; 2l ; 1=2 < < ;Re( ) ; 2l + 3=2; and 1 Z +i1 G (s) x;s ds = x;1=2J (x) I1 = ;1;l 2i ;i1 3 ; ; s 2 for ;Re( ) ; 2l + 3=2 < < ;Re( ) ; 2l + 7=2. (ii) If < 5=2; then Z +i1 G (s) 1 x;s ds = x;3=2J;2;l+2 (x) I2 = 7 3 2i ;i1 2 ;;s 2 ;;s for ;Re( ) ; 2l ; 1=2 < < ;Re( ) ; 2l + 3=2; and G (s) 1 Z +i1 ;3=2 ;s I2 = 2i ;i1 3 ; ; s 7 ; ; s x ds = x J;2;l+1 (x) 2 2 I1 =
(8.4.14)
(8.4.15)
(8.4.16)
(8.4.17)
279
8.4. The Extended Hankel Transform
for ;Re( ) ; 2l + 3=2 < < ;Re( ) ; 2l + 7=2. (iii) If < 7=2; then G (s) 1 Z +i1 ;s I3 = 2i ;i1 3 ; ; s 7 ; ; s 11 ; ; s x ds 2 2 2 = ;x;5=2 J;3;l+3 (x) for ;Re( ) ; 2l ; 1=2 < < ;Re( ) ; 2l + 3=2; and Z +i1 G (s) 1 x;s ds I3 = 7 11 3 2i ;i1 2 ;;s 2 ;;s 2 ;;s = ;x;5=2 J;3;l+2 (x) for ;Re( ) ; 2l + 3=2 < < ;Re( ) ; 2l + 7=2. For example, to prove (8.4.8) two functions are introduced: 8 1 > > < t1=2; (x2 ; t2 )2 ; if 0 < t < x; 8 h;x (t) = > > : 0; if t > x and ;x (t) = ;x3; t;5=2 J;3;l+3 (xt): By using Lemma 8.4 it is proved that their Mellin transforms are given by
Mh;x (s) =
and
1 s;+ 2
(8.4.18)
(8.4.19)
(8.4.20) (8.4.21)
xs;+9=2
5 9 s;+ 2 s;+ 2
11=2;;s
x : M ;x (s) = 3 7 11 ;;s ;;s ;;s
2 2 2 From these formulas for Re(s) = 1 ; the following relation follows MH ;l ;x (s) = G (s) M ;x (1 ; s) = Mh;x (s); so that H ;l ;x = h;x : Then in accordance with (8.4.4)
(8.4.22)
Z1 dt Z 1 5 =2; 1 =2 ;x (t) H ;lf (t)dt ;x (xt) J;3;l+3 (xt) H k; f (t) t3 = 0 0 Z 1 Z1 = H ;l ;x (t)f (t)dt = h;x (t)f (t)dt 0 0 Zx 1 = 8 t1=2; (x2 ; t2 )2 f (t)dt: 0
(8.4.23)
280
Chapter 8. Bessel Type Integral Transforms on the Space L;r
A direct calculation shows that 1 1 d 3 Z x t1=2; (x2 ; t2 )2f (t)dt = x;1=2; f (x) 8 x dx 0 and so di erentiating (8.4.23), (8.4.8) follows. The validity of the above are justi ed by the conditions of the theorem. The third case when = ;Re( ) ; 2l + 3=2 is much harder, and the results are given in terms of the integral in the Cauchy sense de ned by Z !1
0
f (t)dt =
lim R!1
Z
R
0
f (t)dt;
(8.4.24)
provided that f (x) is integrable over (0; R) for every R > 0 (see Titchmarsh [3, Section 1.7]).
Theorem 8.15. Let 1 < r < 1 and = ;Re() ; 2l + 3=2. (a) If 0 < Re() + 2l < 3=2 ; (r) and f 2 L;r ; then for almost all x > 0; the following
inversion relation holds:
+1=2
f (x) = x
Z dt d 2 3=2; !1 x ( xt)1=2J;2;l+2 (xt) H ;l f (t) 2 : x dx t 0
(8.4.25)
Z dt d 1=2; !1 x ( xt)1=2J;1;l+1 (xt) H ;l f (t) : dx t 0
(8.4.26)
1
(b) If 1=2 < Re()+2l 5 3=2 ; (r) and f 2 L;r ; then for almost all x > 0; the following inversion relation holds: ;1=2
f (x) = ;x
Proof. For real the statements (a) and (b) were proved by Heywood and Rooney [6, Theorems 6.6 and 6.9]. They are directly extended to complex by the same arguments which were used in Heywood and Rooney [6]. In conclusion we note that the extended Hankel transform (8.4.1) has constancy of the range similar to that for the Hankel transform in (8.1.20): if 1 < r < 1, (r) 5 < Re( ) + 2l + 3=2 and Re( ) = jRe( ) + 2lj, then except when = ;Re( ) ; 2l + 3=2 and Re( ) < ;1, H ;l (L;r ) = H ;l (L;r ):
(8.4.27)
The proof of this property is given by the same arguments that were used by Rooney [5, Theorem 2] to prove such a result for real and .
8.5. The Hankel Type Transform We consider the integral transform de ned by
H ;;$;k; f (x) = x
Z1
0
J (xt)1=k t$ f (t)dt
(x > 0);
(8.5.1)
where Re( ) > ;1, 2 R, $ 2 R, k > 0, > 0 and J (x) is the Bessel function of the rst kind of order . This transform is clearly de ned for f 2 C0. When = k and
281
8.5. The Hankel Type Transform
= $ = 1=k ; 1=2, the transform coincides with the generalized Hankel transform H k; given in (3.3.4), which, if further k = 1, is the Hankel transform H in (8.1.1). So, H ;;$;k; is named a Hankel type transform. As in Section 8.1, we rst give the results characterizing the boundedness and the representation of the Hankel type transform (8.5.1) in the space L;r .
Theorem 8.16. Let 1 5 r 5 1 and let (r) be given in (3:3:9): (a) If 1 < r < 1 and (r) 5 k( ; $ ; 1) + 3=2 < Re() + 3=2; then for all s = r
such that s0 > [k( ; $ ; 1) + 3=2];1 and 1=s + 1=s0 = 1; the operator H ;;$;k; belongs to [L;r ; L1; +$;;s ] and is a one-to-one transform from L;r onto L1; +$;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:5:1) for Re(s) = 1 ; + $ ; is given by
MH ;;$;k; f (s)
; 21 f + k + ksg Mf (1 + $ ; ; s): (8.5.2) =2 1 ; 2 f ; k ; ksg + 1 (b) If 1 5 k( ; $ ; 1) + 3=2 5 Re() + 3=2; then H ;;$;k; 2 [L;1; L1;+$;;1 ]. If 1 < k( ; $ ; 1)+3=2 < Re( )+3=2; then H ;;$;k; 2 [L;1 ; L1; +$;;r ] for all r (1 < r < 1). (c) If f 2 L;r and g 2 L+$;;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r + 1=s = 1 and max[ (r); (s)] 5 k( ; $ ; 1) + 3=2 < Re( ) + 3=2; then the relation
k 2 k(+s)
Z1 0
f (x) H ;;$;k;g (x)dx =
Z 1 0
H ;$;;k; f (x)g (x)dx
(8.5.3)
holds.
(d) If f 2 L;r ; where 1 < r < 1 and (r) 5 k( ; $ ; 1) + 3=2 < Re()+ 3=2; then the
relation
d x(+1)=k; H k +1;;$ ;k; M;1=k f (x) dx Z1 k +1;( +2)=k d ( +1)=k 1=k $ f (t) dt (8.5.4) x J t = x +1 (xt) dx t1=k 0 holds for almost all x > 0. Proof. It is directly veri ed that the Hankel type transform (8.5.1) can be represented via the Hankel transform (8.1.1) as
H ;;$;k; f (x) = x+1;(+2)=k
H ;;$;k; f (x) = k;k($+1) M;1=(2k) N1=k H Mk($+1);3=2 WNk f (x)
or
H ;;$;k;f (x) = k;k($+1) N1=k Mk;1=2 H Mk($+1);3=2 WNk f (x);
(8.5.5) (8.5.6)
where the operators M and W are given in (3.3.11) and (3.3.12) and the operator Na is de ned by
Naf (x) = f (xa) (a 2 R; a 6= 0):
(8.5.7)
282
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Here we used the clear operator equality
Na M = Ma Na:
(8.5.8)
Then the assertion (a) follows from Theorem 8.1(a), Lemma 3.1(i),(ii) and from the following similar result for the operator (8.5.7):
Lemma 8.5 For 2 R and 1 5 r < 1; Na is an isometric isomorphism of L;r onto
La;r : If f
2 L;r (1 5 r 5 2); then for Re(s) = a
s 1 MNa f (s) = jaj Mf a :
(8.5.9)
Assertion (b) follows from (8.5.5) and Theorem 8.1(b) if we note that Lemmas 3.1(i) and 8.5 remain true for the space L;1 . (c) is proved similarly to that in Theorem 8.1(c). The statement (d) is proved on the basis of (8.5.6), if we use Theorem 8.1(d), the equality (8.5.8) and the directly veri ed operator relation d: (8.5.10) NaD = 1a M1;a DNa with D = dx The range of H ;;$;k;(L;r ) of the Hankel type transform (8.5.1) in L;r -space is characterized in terms of the operators M ; Na in (3.3.11), (8.5.7), the Erdelyi{Kober operator I ; in (8.1.21) and the Fourier cosine transform Fc in (8.1.2).
Theorem 8.17. Let 1 < r < 1 and let (r) be given by (3:3:9). If (r) 5 k( ; $
; 1) + 3=2 < Re() + 3=2; then there holds
H ;;$;k;(L;r ) = N1=k Mk(+ ;$;1)+1; (r) Ik( ;$;1); (r)+3=2;;1=2Fc
In particular; if 1=2 5 k( ; $ ; 1) + 3=2 < Re( ) + 3=2; then
L (r);r : (8.5.11)
H ;;$;k; (L;2 ) = N1=k Mk(+ ;$;1)+1=2 Ik( ;$;1)+1;;1=2 Fc L2 (R+ ) :
(8.5.12)
Proof. Using the representation (8.5.6), Lemma 3.1(i),(ii) and Lemma 8.5 and applying
Lemma 8.2 with being replaced by k( ; $ ; 1)+3=2, we have for f 2 L;r the representation H ;;$;k; f = k;k($+1) 2 (r);k( ;$;1);3=2 N1=k Mk(+ ;$;1)+1; (r)
Ik ;$; ; r = ; ;k ;$; r ; = H ;k ;$; r ; = Mk; r WNk f: (
1)
(
( )+3 2 [
1)+ ( ) 3 2
(
1)+ ( ) 2] 2
( )
(8.5.13)
From here, taking the same arguments as in Theorem 8.2, we obtain (8.5.11) and (8.5.12). Finally we present the inversion for the Hankel type transform (8.5.1) in the space L;r .
283
8.5. The Hankel Type Transform
Theorem 8.18. Let 1 < r < 1 and (r) 5 k( ; $ ; 1) + 3=2 < Re() + 3=2; or r = 1
and 1 5 k( ; $ ; 1) + 3=2 5 Re( ) + 3=2; where (r) is given in (3:3:9). If we choose an integer m > k( ; $ ; 1) + 3=2 and if f 2 L;r ; then the inversion relation 2;m d m x(+m)=k x(2;)=k;$;1 x1;2=k dx f (x) = k Z1
dt (8.5.14) J+1 (xt)1=k t2=k;;1 H ;;$;k;f (t) tm=k 0 holds for almost all x > 0: In particular; if 1 < r < 1 and (r) 5 k( ; $ ; 1) + 3=2 < min[1; Re( ) + 3=2]; then d x(+1)=k f (x) = k x;$;=k dx Z1 (8.5.15) J+1 (xt)1=k t2=k;;1 H ;;$;k;f (t) t1dt=k : 0 Proof. According to (3.3.11), (3.3.12), (8.5.7), Lemma 3.1(i),(ii) and Lemma 8.5 the operators inverse to M , W and Na have the forms
M;1 = M; ; W;1 = W1= and Na;1 = N1=a;
(8.5.16)
respectively, and they are isometric isomorphisms in the corresponding spaces. It also follows from Theorem 8.4 that under the conditions of our theorem the operator H can be inverted in the space Lk( ;$;1)+3=2;r . Then from the relation (8.5.6) we obtain the inversion formula for (8.5.1):
f (x) =
k;k($+1) N
=k Mk;1=2 H Mk($+1);3=2W Nk
1
;1
H ;;$;k; f (x)
;1 N ;1 H ;;$;k;f (x) = k1 k($+1) Nk;1W;1 Mk;(1$+1);3=2H ; 1 Mk ;1=2 1=k
= k1 k($+1) N1=k W1=M3=2;k($+1)H ; 1 M1=2;k Nk H ;;$;k; f (x);
(8.5.17)
W (M D)m = (1; )m (M D)mW (m = 1; 2; ); Na(M D)m = a;m(Ma(;1)+1D)m Na (m = 1; 2; );
(8.5.18)
where H ; 1 is the operator inverse to the Hankel transform (8.1.1). Using the relation (8.1.34), the equalities (8.5.8), (3.3.22) and the directly veri ed formulas (8.5.19)
we arrive at (8.5.14). In particular, if k( ; $ ; 1) + 1=2 < 0; we obtain (8.5.15). Setting = $ = 1=k ; 1=2 and = k, from Theorems 8.16{8.18 we have the corresponding statements for the generalized Hankel transform H k; given in (3.3.4).
Theorem 8.19. Let 1 5 r 5 1 and let (r) be given in (3:3:9): (a) If 1 < r < 1 and (r) 5 k( ; 1=2) + 1=2 < Re() + 3=2; then for all s = r such that
s0 > [k( ; 1=2) + 1=2];1 and 1=s + 1=s0 = 1; the operator H k; belongs to [L;r ; L1;;s ] and
284
Chapter 8. Bessel Type Integral Transforms on the Space L;r
is a one-to-one transform from L;r onto L1;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of H k; f for Re(s) = 1 ; is given in (3:3:10) : 1 + k s ; 1 + 1 ; 2 k(s;1=2) 2 2 Mf (1 ; s): (8.5.20) MH k; f (s) = 1 1 k ; 2 ;k s; 2 +1 (b) If 1 5 k( ; 1=2) + 1=2 5 Re() + 3=2; then H k; 2 [L;1; L1;;1]. If 1 < k( ; 1=2) + 1=2 < Re( ) + 3=2; then H k; 2 [L;1 ; L1;;r ] for all r (1 < r < 1). (c) If f 2 L;r and g 2 L;s ; where 1 < r < 1 and 1 < s < 1 such that 1=r + 1=s = 1 and max[ (r); (s)] 5 k( ; 1=2) + 1=2 < Re( ) + 3=2; then the relation Z1 0
holds.
f (x) H k; g (x)dx =
Z 1 0
H k; f (x)g (x)dx
(8.5.21)
(d) If f 2 L;r ; where 1 < r < 1 and (r) 5 k( ; 1=2) + 1=2 < Re() + 3=2; then the
relation
d x=k+1=2H M f k;+1 ;1=k (x) dx d x(+1)=k Z 1 J k(xt)1=k t;1=2f (t)dt = x1=2;(+1)=k dx +1 0 holds for almost all x > 0.
H k; f (x) = x1=2;(+1)=k
(8.5.22)
Theorem 8.20. Let 1 < r < 1 and (r) be given by (3:3:9). If (r) 5 k( ; 1) + 1=2 < Re( ) + 3=2; then there holds H k; (L;r ) = N1=k Mk( ;1)+1; (r) Ik( ;1=2); (r)+1=2;;1=2Fc L (r);r : (8.5.23) In particular; if 1=2 5 k( ; 1) + 1=2 < Re( ) + 3=2; then H k; (L;2 ) = N1=k Mk( ;1)+1=2 Ik( ;1=2);;1=2Fc L2 (R+ ) : (8.5.24) Theorem 8.21. Let 1 < r < 1 and (r) 5 k( ; 1=2) + 1=2 < Re() + 3=2; or r = 1
and 1 5 k( ; 1=2)+1=2 5 Re( )+3=2; where (r) is given in (3:3:9): If we choose an integer m > k( ; 1=2) + 1=2 and if f 2 L;r ; then the inversion relation m ( +m;1)=k +1=2 (1; )=k ;1=2 1;2=k d f (x) = x x dx x Z1 dt (8.5.25) (xt)1=k;1=2J+1 k(xt)1=k H k; f (t) tm=k 0 holds for almost all x > 0. In particular; if 1 < r < 1 and (r) 5 k( ; 1=2) + 1=2 < min[1; Re( ) + 3=2]; then d x=k+1=2 f (x) = x1=2;(+1)=k dx Z1 (8.5.26) (xt)1=k;1=2J+1 k(xt)1=k H k; f (t) t1dt=k : 0
285
8.6. Hankel{Schwartz and Hankel{Cli ord Transforms
8.6. Hankel{Schwartz and Hankel{Cli ord Transforms Let us investigate the integral transforms
h f (x) = b f
J (xt)t f (t)dt (x > 0);
(8.6.2)
2 +1
0
(x) = x
;1
(8.6.1)
0
Z1
;2
J(xt)f (t)dt (x > 0);
2 +1
;1
and
Z1
h f (x) = x
b f (x) = ;2
Z1 0
Z1 0
with the kernels
J (z) = z; J (z);
C (xt)f (t)dt (x > 0);
(8.6.3)
C (xt)t f (t)dt (x > 0)
(8.6.4)
p C(z) = z;=2J (2 z)
(8.6.5)
for 2 R ( > ;1): The transforms (8.6.1), (8.6.2) and (8.6.3), (8.6.4) de ned for f 2 C0 are called the Hankel{Schwartz and Hankel{Cli ord transforms, respectively. They are special cases of the general Hankel transform H ;;$;k; given in (8.5.1):
h f (x) x ;1
+1
0
h f (x) x;
Z1
;2
and
b f ;1
(x) x=2
Z1 0
b f (x) x;=
2
;2
Z1
0
J (xt)t+1 f (t)dt = H ;;;+1;1;1f (x);
J (2(xt)1=2)t;=2f (t)dt = H ;=2;;=2;2;2f (x);
Z1 0
J (xt)t; f (t)dt = H ;+1;;;1;1f (x);
J (2(xt)1=2)t=2f (t)dt = H ;;=2;=2;2;2f (x)
(8.6.6) (8.6.7) (8.6.8) (8.6.9)
for > ;1 and x > 0: These relations show that h;1 and h;2 as well as b;1 and b;2 are mutually conjugate operators. Using the results in Theorems 8.16{8.18, we obtain the following statements giving the theory of the transforms h;1; h;2; b;1 and b;2 in the space L;r .
Theorem 8.22. Let 1 5 r 5 1 and let (r) be given in (3:3:9): (a) If 1 < r < 1 and (r); ;1=2 5 < 1; then for all s = r such that s0 > [ + +1=2]; and 1=s + 1=s0 = 1; the operator h belongs to [L;r ; L; ; ;s ] and is a one-to-one transform from L;r onto L; ; ;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of h f for 1
;1
2
2
Re(s) = ; ; 2 is given by
;1
; + s +2 1 Mh;1f (s) = 2+s 1 ; s ; 2
Mf (;2 ; s):
(8.6.10)
286
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(b) If 1=2 ; 5 5 1; then h 2 [L; ; L;; ;1 ]. If 1=2 ; < < 1; then h 2 ;1
1
2
;1
[L;1 ; L; ;2;r ] for all r (1 < r < 1). (c) If f 2 L;r and g 2 L;2;1;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r + 1=s = 1 and max[ (r); (s)] ; ; 1=2 5 < 1; then the relation Z1
h f (x)g(x)dx (8.6.11) holds; where h is the operator (8:6:2) conjugate to h : (d) If f 2 L;r ; where 1 < r < 1 and (r) ; ; 1=2 5 < 1; then the relation 0
f (x) h;1g (x)dx =
Z 1 0
;2
;2
;1
Z1 d +1 (8.6.12) h;1f (x) = dx x 0 J+1 (xt)t; f (t) dtt holds for almost all x > 0. (e) If 1 < r < 1 and (r) ; ; 1=2 5 < 1; then there holds the relation h;1(L;r ) = M+2+1; (r) I+; (r)+1=2;;1=2Fc L (r);r : (8.6.13) In particular; h;1(L;2) = M+2+1=2I+;;1=2Fc L2(R+ ) : (8.6.14) (f) Let 1 < r < 1 and (r) ; ; 1=2 5 < 1; or r = 1 and ; + 1=2 5 5 1. If we choose an integer m > + + 1=2 and if f 2 L;r ; then the inversion relation m Z1 d 1 +m J+1(xt)t;(+m) h;1 f (t)dt (8.6.15) f (x) = x x dx x 0 holds for almost all x > 0. In particular; if 1 < r < 1 and (r) ; ; 1=2 5 < min[1; ; + 1=2]; then Z1 d +1 J+1 (xt)t;;1 h;1f (t)dt: (8.6.16) f (x) = dx x 0
Theorem 8.23. Let 1 5 r 5 1: (a) If 1 < r < 1 and (r) + + 1=2 5 < 2 + 2; then for all s = r such that 0 s > [ ; ; 1=2]; and 1=s + 1=s0 = 1; the operator h belongs to [L;r ; L ;;s ] and is 1
;2
2 +2
a one-to-one transform from L;r onto L2+2;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of h;2f for Re(s) = 2 + 2 ; is given by ; 2s Mf (2 + 2 ; s): (8.6.17) Mh;2 f (s) = 2s;;1 s ; +1; 2 (b) If + 3=2 5 5 2 + 2; then h;2 2 [L;1; L2+2;;1 ]. If + 3=2 < < 2 + 2; then h;2 2 [L;1; L2+2;;r ] for all r (1 < r < 1). (c) If f 2 L;r and g 2 L+2+1;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r + 1=s = 1 and max[ (r); (s)]+ + 1=2 5 < 2 + 2; then the relation Z1 0
f (x) h;2g (x)dx =
Z 1 0
h f (x)g(x)dx ;1
(8.6.18)
287
8.6. Hankel{Schwartz and Hankel{Cli ord Transforms
holds; where h;1 is the operator (8:6:1) conjugate to h;2 . (d) If f 2 L;r ; where 1 < r < 1 and (r) + + 1=2 5 < 2 + 2; then the relation Z1 (8.6.19) h;2f (x) = x;2;1 dxd x+1 0 J+1(xt)t f (t)dt holds for almost all x > 0. (e) If 1 < r < 1 and (r) + + 1=2 5 < 2 + 2; then there holds the relation
h (L;r ) = M; ; ; r I;; r ; = ;; = Fc ;2
2
1
( )
( ) 1 2
1 2
In particular; if + 1 5 < 2 + 2; then
L (r);r :
(8.6.20)
h (L; ) = M; ; = I;; ;; = Fc L (R ) : ;2
2
2
3 2
1
2
1 2
(8.6.21)
+
(f) Let 1 < r < 1 and (r) + + 1=2 5 < 2 + 2; or r = 1 and + 3=2 5 5 2 + 2.
If we choose an integer m > ; ; 1=2 and if f 2 L;r ; then the inversion relation d m x+m Z 1 J (xt)t;m+1 h f (t)dt (8.6.22) f (x) = x;2 x1 dx +1 ;2 0 holds for almost all x > 0. In particular; if 1 < r < 1 and (r) + + 1=2 5 < min[ + 3=2; 2 + 2]; then d x+1 Z 1 J (xt)t h f (t)dt: (8.6.23) f (x) = x;2;1 dx +1 ;2 0
Theorem 8.24. Let 1 5 r 5 1: (a) If 1 < r < 1 and ( (r) ; )=2 + 1=4 5 < 1; then for all s = r such that s0 > [2 + ; 1=2]; and 1=s + 1=s0 = 1; the operator b belongs to [L;r ; L ; ;;s ] and is a 1
;1
1
one-to-one transform from L;r onto L1; ;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of b;1f for Re(s) = 1 ; ; is given by ;( + s) Mf (1 ; ; s): (8.6.24) Mb;1 f (s) = ;(1 ; s) (b) If ;=2 + 3=4 5 5 1; then b;1 2 [L;1; L1;;;1 ]. If ;=2 + 3=4 < < 1; then b;1 2 [L;1; L1;;;r ] for all r (1 < r < 1). (c) If f 2 L;r and g 2 L;;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r + 1=s = 1 and (max[ (r); (s)] ; )=2 + 1=4 5 < 1; then the relation Z1 0
f (x) b;1g (x)dx =
Z 1 0
b f (x)g(x)dx ;2
(8.6.25)
holds; where b;2 is the operator (8:6:4) conjugate to b;1 : (d) If f 2 L;r ; where 1 < r < 1 and ( (r) ; )=2 + 1=4 5 < 1; then the relation Z1 (8.6.26) b;1f (x) = dxd x(+1)=2 0 J+1 2(xt)1=2 t;(+1)=2f (t)dt holds for almost all x > 0.
288
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(e) If 1 < r < 1 and ( (r) ; )=2 + 1=4 5 < 1; then there holds the relation b (L;r ) = N = M ; ; r I ; r ; = ;; = Fc L r ;r : (8.6.27) ;1
1 2
2( + ) 1
( ) 2 +
( ) 1 2
1 2
( )
In particular; if (1 ; )=2 5 < 1; then
b (L; ) = N = M
I ;1;;1=2Fc L2(R+ ) : (8.6.28) (f) Let 1 < r < 1 and ( (r) ; )=2 + 1=4 5 < 1; or r = 1 and ;=2 + 3=4 5 5 1. If we choose an integer m > 2 + ; 1=2 and if f 2 L;r ; then the inversion relation m Z1 d ( +m)=2 J+1 2(xt)1=2 t;(+m)=2 b;1f (t)dt (8.6.29) f (x) = dx x 0 holds for almost all x > 0. In particular; if 1 < r < 1 and ( (r) ; )=2 + 1=4 5 < min[1; ;=2 + 3=4]; then Z1 d ( +1)=2 J+1 2(xt)1=2 t;(+1)=2 b;1f (t)dt: (8.6.30) f (x) = dx x 0 ;1
2
1 2
;=
2( + ) 3 2 2 +
Theorem 8.25. Let 1 5 r 5 1: (a) If 1 < r < 1 and ( (r) + )=2 + 1=4 5 < + 1; then for all s = r such that s0 > [2 ; ; 1=2]; and 1=s + 1=s0 = 1; the operator b belongs to [L;r ; L ; ;s ] and is 1
;2
1
+
a one-to-one transform from L;r onto L1; +;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of b;2f for Re(s) = 1 ; + is given by ;(s) Mf (1 + ; s): (8.6.31) Mb;2 f (s) = ;(1 + ; s) (b) If =2 + 3=4 5 5 + 1; then b;2 2 [L;1 ; L1;+;1 ]. If =2 + 3=4 < < + 1; then b;2 2 [L;1; L1;+;r ] for all r (1 < r < 1). (c) If f 2 L;r and g 2 L+;s ; where 1 < r < 1 and 1 < s < 1 are such that 1=r + 1=s = 1 and (max[ (r); (s)] + )=2 + 1=4 5 < + 1; then the relation Z1 0
f (x) b;2g (x)dx =
Z 1 0
b f (x)g(x)dx
(8.6.32)
;1
holds; where b;1 is the operator (8:6:3) conjugate to b;2 : (d) If f 2 L;r ; where 1 < r < 1 and ( (r) + )=2 + 1=4 5 < + 1; then the relation Z1 (8.6.33) b;2f (x) = x; dxd x(+1)=2 0 J+1 2(xt)1=2 t(;1)=2f (t)dt holds for almost all x > 0. (e) If 1 < r < 1 and ( (r) + )=2 + 1=4 5 < + 1; then there holds the relation
b (L;r ) = N = M ;2
1 2
In particular; if (1 + )=2 5 < + 1; then
b (L; ) = N = M ;2
2
L (r);r : 2( ; );1; (r ) I2 ; ; (r );1=2;;1=2 Fc
1 2
2(
;);3=2I2 ;;1;;1=2 Fc
L2(R+ ) :
(8.6.34) (8.6.35)
8.7. The Transform
Y
289
(f) Let 1 < r < 1 and ( (r)+ )=2+1=4 5 < +1; or r = 1 and =2+3=4 5 5 +1.
If we choose an integer m > 2 ; ; 1=2 and if f 2 L;r ; then the inversion relation
d m x(+m)=2 Z 1 J 2(xt)1=2 t(;m)=2b f (t)dt (8.6.36) +1 ;2 dx 0 holds for almost all x > 0. In particular; if 1 < r < 1 and ( (r) + )=2 + 1=4 5 < min[=2 + 3=4; + 1]; then d x(+1)=2 Z 1 J 2(xt)1=2 t(;1)=2 b f (t)dt: (8.6.37) f (x) = x; dx +1 ;2 0 f (x) = x;
8.7. The Transform Y We consider the integral transform Y de ned by
Y f
Z1
(x ) =
0
(xt)1=2Y (xt)f (t)dt (x > 0);
(8.7.1)
where Y (z ) is the Bessel function of the second kind (or Neumann function) given via the Bessel function of the rst kind (2.6.2) by (8.7.2) Y (z) = sin(1) [J (z) cos( ) ; J; (z)] (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2(4)]). Since the Hankel transform (2.6.1) is de ned for 2 C (Re( ) > ;1) the transform Y can be de ned for 2 C (jRe( )j < 1). First we give the representation of the transform Y in (8.7.1) in terms of the Hankel transform H in (8.1.1), the even Hilbert transform H + in (8.3.1) and the elementary operator M in (3.3.11).
Theorem 8.26. For 2 C with jRe()j < 1 there holds the relation Y
= H M;1=2H + M1=2;
(8.7.3)
on C0 being the collection of continuous functions with compact support on R+ . Proof. Since M1=2; f 2 C0 LRe();2 and jRe()j < 1; by Theorem 8.9(a) H +M1=2; f 2 LRe();2 and thus Lemma 3.1(i) implies M;1=2H + M1=2; f 2 L1=2;2 = L2(R+ ). Hence Theorem 8.1(d) and the use of the function h;x in (8.1.13) imply that for almost all x > 0 H M;1=2
H
M1=2; f (x) Z1 dt +1=2 1=2 ;1=2 H M ; ( +1=2) d x ( xt ) J =x +1 (xt)t + 1=2; f (t) dx t 0 Z 1 d M;1=2 h;x (t) H + M1=2;f (t)dt: = x;(+1=2) dx 0 +
(8.7.4)
290
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Since the intervals (;Re( ) ; 1=2; 1=2) and (Re( ) ; 1=2; Re( ) + 3=2) intersect, is taken from their intersection. From ;Re( ) ; 1=2 < < 1=2; h;x 2 L;r for any r (1 < r < 1) due to Lemma 8.1(b), we have
M;1=2h;x 2 L ;Re()+1=2;r;
(8.7.5)
when 0 < ; Re( ) + 1=2 < 2 because of Re( ) ; 1=2 < < Re( ) + 3=2. Replacing ; Re( )+ 1=2 by 1 ; 1 , we see that the new number 1 satis es ;1 < 1 < 1 and M;1=2h;x 2 L1;1 ;r ; in particular, M;1=2h;x 2 L1;1 ;2. But since f 2 C0; we nd M1=2; f 2 L;2 for any . So
M1=2; f 2 L1;2 ;
M;1=2h;x 2 L1;1 ;2
for such a 1 (;1 < 1 < 1). Then we can apply Theorem 8.9(c) to (8.7.4) and in accordance with the formula of integration of parts (8.3.5), we have
H M;1=2
H
M1=2; f (x) Z 1 1=2; ; ( +1=2) d H M f (t)dt: = ;x ; ; 1=2 h;x (t)t dx 0 To evaluate the inner integral in (8.7.6) we prove the following auxiliary result. +
Lemma 8.6. If 2 C with jRe()j < 1; then for almost all x > 0;
H
; M;1=2h;x (t) = ;x+1 t;1
"
#
+1 2 ;( + 1) : Y+1 (xt) + xt
(8.7.6)
(8.7.7)
Proof. The proof is based on the technique of the Mellin transform (3.2.5) and residue theory. By (8.7.5) and Theorem 8.9(b), (H ; M;1=2h;x )(t) exists almost everywhere on R+ and belongs to L ;Re()+1=2;r for some (jRe( )j < 1) and any r (1 < r < 1). Then for r = 2 we take the Mellin transform of the left-side of (8.7.7). Applying (8.3.13), (3.3.14), (8.1.14), (8.1.4) and the clear equality x+s+1=2 ; (8.7.8) Mg:x (s) = + s + 21 we have for Re(s) = ; Re( ) + 1=2
H
M ; M;1=2h;x
s (s) = cot 2 MM;1=2h;x (s) 1 Mh;x s + ; = cot s 2 2 1 s = cot 2 MH g;x s + ; 2 ; + 2s 3 Mg;x ; ; s = 2s+;1 s cot s 2 2 ; 1; 2
8.7. The Transform
Y
291
s ;s ; + 2 cot s : = 2;2x2 x2 2 ; 2 ; 2s
Hence, by (3.2.6)
H ;M; = h;x
1 2
where 1 I (z) = Rlim !1 2i
(t) = 2;2 x2 I (xt);
2
+ 2s s ds cot s 2 ; 2; 2
Z 1 +iR ;s ; z
1 ;iR
(8.7.9)
and the limit is taken in the topology of L1 ;2. Closing the contour to the left and calculating the residues of the integrand at the simple poles s = ;2(k + ) (k = 0; 1; 2; ) and s = ;2m (m = 0; 1; 2; ) in view of the relations (1.3.3), (2.1.6) and (2.6.2), we have
I (z ) =
1 z 2(+k) X
2
k=0
2(;1)k cot[;( + k) ] k!;(2 + k + )
1 z 2m ;( ; m) X
+ 2
m=;1 ;1 z
= ;2 2
2 z ; ;( + 1) ; ;(2 + m) 2
2
cot[( + 1) ]
2
2k++1 (;1)k z k=0 k!;( + k + 2) 2
1 X
;1 1 (;1)k z 2k;;1 2 z ;2 X 1 ; 2 ;( + 1) +2 z2 sin[( + 1) ] k=0 k!;(k ; ) 2
;1 1 = ;2 z2 sin[( + 1) ] [cos(( + 1) )J+1(z ) ;2 ;J;(+1)(z)] ; 2 2z ;( + 1) ;2 ;1 Y+1 (z ) ; 2 2z ;( + 1) = ;2 z2 according to (8.7.2). Substituting this result into (8.7.9) we obtain (8.7.7), and the lemma is proved.
We continue the proof of Theorem 8.26. Substituting (8.7.7) into (8.7.6), we have
H M;1=2
H
+
M1=2; f (x)
= x;(+1=2)
"
#
d x+1 Z 1 t;1=2 Y (xt) + ;( + 1) 2 +1 f (t)dt: +1 dx xt 0
(8.7.10)
292
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Due to (8.7.2) and the formulas d [z J (z)] = z J (z); d [z ; J (z )] = ;z; J (z ) (8.7.11) ;1 +1 dz dz (see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2.51]), we have d [z +1Y (z)] = z+1Y (z ): (8.7.12) +1 dz Since f 2 C0; the di erentiation may be taken under the integral sign of (8.7.10). Taking such a di erentiation and using (8.7.12), we have for almost all x > 0;
H M;1=2
H
+ M1=2; f (x) =
Z1 0
(xt)1=2Y (xt)f (t)dt;
which completes the proof of Theorem 8.26. Now we can present the results characterizing the boundedness, the range and the representation of the transform Y (8.7.1) in the space L;r .
Theorem 8.27. Let 1 5 r 5 1 and let (r) be given in (3:3:9). (a) If 1 < r < 1 and (r) 5 < 3=2 ; jRe()j; then for all s = r such that s0 > 1=
and 1=s + 1=s0 = 1; the transform Y can be extended to L;r as an element of [L;r ; L1;;s ]. If further 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:7:1) for Re(s) = 1 ; is given by 1 + s + 1 ; 1 2 2 s ; 1=2 cot MY f (s) = ;2 2 s ; + 2 (Mf )(1 ; s): (8.7.13) ; 21 ; s + 23 (b) If 1 < r < 1 and (r) 5 < 3=2 ; jRe()j; then except when = 1=2 ; Re(); Y is a one-to-one transform from L;r onto L1;;s ; and Y (L;r ) = H (L;r ):
(8.7.14)
= H M;1=2H + M1=2;
(8.7.15)
= ;M1=2; H ; M;1=2 H :
(8.7.16)
Further Y
and Y
(c) For 6= 0; if 1 5 5 3=2 ;jRe()j; Y 2 [L; ; L ;;1 ]; and; if 1 < < 3=2 ;jRe()j; 1
1
Y 2 [L;1 ; L1;;r ] for all r (1 5 r < 1). For = 0; if 1 5 < 3=2; Y0 2 [L;1 ; L1;;1 ]; and; if 1 < < 3=2; Y0 2 [L;1 ; L1;;r ] for all r (1 5 r < 1). (d) Let 1 < r < 1 and 1 < s < 1 such that 1=r + 1=s = 1 and max[ (r); (s)] 5 < 3=2 ; jRe( )j; then for f 2 L;r ; g 2 L;s the following relation holds:
Z1 0
Z 1 f (x) Y g (x)dx = Y f (x)g (x)dx: 0
(8.7.17)
Y
8.7. The Transform
293
(e) If f 2 L;r ; where 1 < r < 1 and (r) 5 < 3=2 ; jRe()j; then for almost all x > 0
the following relation holds:
Y f
d x+1=2 (x) = x;(+1=2) dx Z1
0
(xt)
#
"
=
1 2
+1 f (t) dtt : Y+1(xt) + ;(+ 1) xt2
(8.7.18)
Proof. Since (r) = 1=2; the assumption (r) < 3=2 ; jRe()j implies jRe()j < 1; and
hence by Theorem 8.26 the relation (8.7.15) holds on C0 . It is directly veri ed by using Lemma 3.1(i), Theorem 8.9(a) and Theorem 8.1(a) that, since the assumption (r) 5 < 3=2;jRe( )j implies j ; 1=2 + Re( )j < 1; the transform on the right side of (8.7.15) is in [L;r ; L1;;s ] for any s = r such that s0 > 1= . Thus we may extend Y to L;r by de ning it by (8.7.15) and then Y 2 [L;r ; L1;;s ]. The relation (8.7.13) is proved directly by using (8.7.15), (8.1.4), (3.3.14) and (8.3.12). Thus (a) is established. Due to Lemma 3.1(i), M(;1=2) are isometric isomorphisms. By Theorem 8.9(a) H + maps L +Re();1=2;r one-to-one onto itself except when = 1=2 ; Re( ). The transform H is also one-to-one by Corollary 8.3.1. Then it follows from (8.7.15) that Y is one-to-one except when = 1=2 ; Re( ); and hence (8.7.14) holds. Further Theorem 8.1(a), Lemma 3.1(i) and Theorem 8.9 (b) yield under the conditions in (b) that the transform in the right side of (8.7.16) is in [L;r ; L1;;s ] for some parameter ranges for Y . Also, if f 2 L1=2;2; then (3.3.14), (8.3.13), (3.3.14) and (8.1.4) lead to the equality
;
H
MM1=2; ; M;1=2H f (s)
1 1 +s+ 2 ; s ; + 1 Mf (1 ; s): cot = ;2s;1=2 21 2 2 ; 2 ; s + 23
Thus, by (8.7.13), the relation (8.7.16) holds on L1=2;2; and hence on L;r ; since both sides of (8.7.16) are in [L;r ; L1;;s ]. This completes the proof of assertion (b). The results in (c) for 6= 0 follow from Theorem 8.1(b), since by (8.7.2) Y = cot( )H ; csc( )H ; : When = 0; the results in (c) are proved by direct estimates similar to that in Theorem 8.1(b), if we take into account the asymptotic estimates of Y0 (z ) near zero and in nity:
Y0 (z) = O log(z)
(z ! 0);
Y0(z) = O z ;1=2 (z ! 1)
(8.7.19)
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2(33) and 7.13(4)]). The assertion (d) is proved similarly to that in Theorem 8.1(c). To prove (e) we note that, since = (r) = 1=2 > ;Re( ) ; 1=2; g;x 2 L;r by Lemma 8.1(a). Thus from (8.7.17) we have for all x > 0; 0
Zx 0
Z1 Z 1 +1=2 t Y f (t)dt = g;x (t) Y f (t)dt = Y g;x (t)f (t)dt: 0
0
(8.7.20)
294
Chapter 8. Bessel Type Integral Transforms on the Space L;r
From (8.7.16), (8.1.14) and (8.7.7), we have Y g;x (t) = ; M1=2; H ; M;1=2H g;x (t) = ; M1=2; H ; M;1=2 h;x (t) = x+1=2(xt)1=2
#
"
+1 2 1; ;( + 1) Y+1 (xt) + xt t
and hence (8.7.20) takes the form Zx t+1=2 Y f (t)dt 0
" +1 # Z1 2 ;( ) + 1 +1=2 1=2 f (t) dtt : =x (xt) Y+1 (xt) + xt 0
(8.7.21)
Then the result in (8.7.18) follows on di erentiation. Thus Theorem 8.27 is proved.
Corollary 8.27.1. If 1 < r < 1 and (r) 5 < 3=2 ; jRe()j; except when =
1=2 ; Re( ); then
M; (r)I ; (r);;1=2 Fc (L;r ): In particular; if 1=2 5 < 3=2 ; jRe( )j; except when = 1=2 ; Re( ); then Y (L;2 ) = M ;1=2 I ;1=2;;1=2Fc L2 (R+ ) : Y (L;r ) =
(8.7.22) (8.7.23)
Corollary 8.27.2. If 1 < r < 1 and (r) 5 < 3=2 ; jRe()j; except when =
1=2 ; Re( ); then the range H (L;r ) of the Hankel transform (8:1:1) is invariant under the operator M1=2; H ; M;1=2.
Corollaries 8.27.1 and 8.27.2 follow from Theorems 8.27 and 8.2, if we take into account (8.7.14), (8.1.27) and (8.7.14), (8.7.16), respectively.
Remark 8.3. The boundedness conditions in Theorem 8.27(a) can be extended for
= ;1=2. In fact, if = ;1=2; (8.7.2) implies Y;1=2 = J1=2 and hence Y;1=2 = H 1=2 = Fs by virtue of (8.1.3). Hence by Theorem 8.6(a), Y;1=2 = Fs is a one-to-one transform from L;r onto L1;;s provided that (r) 5 < 2.
Remark 8.4. The exceptional value = 1=2 ; Re(); for which Y (L;r ) 6= H (L;r ) and
the results in Corollaries 8.27.1 and 8.27.2 fail, is only possible if ;1=2 < Re( ) 5 0; since the condition (r) 5 1=2 ; Re( ) < 3=2 ; jRe( )j is equivalent to ;1=2 < Re( ) 5 1=2 ; (r) and (r) = 1=2. Further, if Re( ) = 0; then r = 2; and thus 3 1 (8.7.24) Yi (L;r ) = H i (L;r ) 2 R; 1 < r < 1; r 6= 2; 2 < < 2 : In particular, 3 1 (8.7.25) Y0(L;r ) = H 0(L;r ) 1 < r < 1; r 6= 2; 2 < < 2 :
8.7. The Transform
Y
295
2 Remark 8.5. Since on L1=2;2 = L2 (R+ ); H = I (see Remark 8.1 in H L2 (R+ ) = L2 (R+ ) and in accordance with (8.7.14), Y L2(R+ ) = H L2 (R+ ) = L2(R+ ) (jRe( )j < 1):
Section 8.1), then (8.7.26)
Finally we present the inversion for the transform Y in (8.7.1) on L;r in terms of the Struve function H (z ) de ned by 2k++1 1 X z (;1)k (8.7.27) H (z) = 3 ; k++ 3 2 k=0 ; k + 2 2
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.5(55)]).
Theorem 8.28. Let 1 < r < 1 and (r) 5 < min[1=2 ; Re(); 3=2 + Re()]; where
(r) is given in (3:3:9). For f 2 L;r and for almost all x > 0; the following inversion relation holds: Z1 dt +1=2 1=2 ; ( +1=2) d x ( xt ) H (8.7.28) f (x) = x +1 (xt) Y f (t) dx t: 0 Proof. Since (r) = 1=2; 1=2 < min[1=2 ; Re(); 3=2 + Re()]; and it follows that ;1 < Re() < 0; so that (r) 5 < 3=2 + Re() = 3=2 ; jRe()j. Thus from Theorem 8.27(a), Y f exists and is in L1;;r . Hence, by Lemma 3.1(i), M+1=2 Y f 2 L1=2; ;Re();r : Since ;1 < Re( ) < 0; 1 1 3 1 ; Re() + 2 < 2 5 (r) 5 < min 2 ; Re(); 2 + Re() 5 1: Hence, by Lemma 8.1(b), h;x 2 L;r ; and thus M;(+1=2) h;x 2 L1=2+ +Re();r . We also note that ;1 < 1=2 + + Re( ) < 1; since from Re( ) > ;1 and the assumption ;Re() ; 32 < ; 21 < < 21 ; Re(): Therefore we can apply Theorem 8.9(c) to obtain from (8.3.5) the relation 0
;
Z 1
0
M;(+1=2)h;x (t)
0
=
Z 1 0
H
H ;M
+
= Y f
+1 2
(t)dt
M;(+1=2)h;x (t) M+1=2 Y f (t)dt:
(8.7.29)
Noting 1 Z 1 J (ajxj) jxj; dx = ;sign y jy j; H (ajy j) a > 0; Re( ) > ; 3 ;1 x;y 2 (see Erdelyi, Magnus, Oberhettinger and Tricomi [4, 15.3(15)]) and remembering that H + is the restriction on R+ of the Hilbert transform of even functions, we nd
H
+
M;(+1=2)h;x (t) = ;x+1 t;(+1) H+1 (xt);
(8.7.30)
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Chapter 8. Bessel Type Integral Transforms on the Space L;r
where H+1 (z ) is the Struve function (8.7.27). Also, by applying (8.7.16), (8.3.14) and (8.3.4), we have
H ; M
= Y f
+1 2
= ;H ; M+1=2 M1=2; H ; M;1=2H f
= ;H ; M1 H ; M;1 M+1=2 H f = ;H ; H + M+1=2 H f = M+1=2H f:
(8.7.31)
Substituting (8.7.30) and (8.7.31) into (8.7.29) and using (8.1.13), we obtain Z1 x+1=2 (xt)1=2J+1 (xt) H f (t) dtt 0 Z1 (8.7.32) = x+1=2 (xt)1=2H+1 (xt) Y f (t) dtt : 0 Since, as noted, (r) 5 < Re( )+3=2 and < 1; the result in (8.7.28) follows from Theorem 8.3. This completes the proof of Theorem 8.28. In Theorem 8.28 the inversion formula for the transform Y was established for < 1=2 ; Re( ). In the case > 1=2 ; Re( ) there holds the following result.
Theorem 8.29. Let 1 < r < 1 and (r) 5 < 1; where (r) is given in (3:3:9); and let 1=2 < + Re( ) < 3=2: If f 2 L;r ; then for almost all x > 0; Z1 h i +1=2 1=2 Y f (t) dt ; ; ( +1=2) d x ( xt ) H (8.7.33) f (x) = x +1 (xt) ; A (xt) dx t 0 where 1 : (8.7.34) A = 3 1 = 2 2 ; + 2 Proof. The proof is based on two preliminary lemmas for the auxiliary functions h i h (t) = t; = H (t) ; A t (8.7.35) 1 2
and
+1
8 < t+1=2 x;(+3=2); r;x(t) = : 0;
if 0 < t < x; if t > x:
(8.7.36)
Lemma 8.7. If 1=2 ; Re() < < 1; then h 2 L;r for 1 5 r < 1. If 1=2 5 < 1 and
1=2 ; < Re( ) < 1; then for Re(s) = ; 1 1 ; 2 +s+ 2 1 1 : s ; 1= 2 tan s + + Mh (s) = 2 2 2 ;s+ 3 ; 21 ; s + 23 2
(8.7.37)
8.7. The Transform
Y
297
Lemma 8.8. If 1=2 5 < 1 and 1=2 5 + Re() < 3=2; then for x > 0; Y W1=xh
= r;x;
(8.7.38)
where the operator W is given in (3.3.12). For real Lemmas 8.7 and 8.8 were proved by Heywood and Rooney [4, Lemmas 4.3 and 4.4]. Their proofs can be directly extended to complex . To prove Theorem 8.29, we rst note that, from the assumption of the theorem, Re( ) < 1 and < 3=2 ; jRe( )j. Thus by Lemma 8.7, h 2 L;r ; and by Theorem 8.27(a) Y f exists. So we can apply Theorem 8.27(d) and Lemma 8.8, and by virtue of (8.7.35), (8.7.17), (8.7.38) and (8.7.36) we have 0
x+1=2
Z1 0
h
(xt)1=2 H+1 (xt) ; A (xt)
Z 1 +3=2 (W1=xh )(t) Y f (t)dt = x Y W1=xh (t)f (t)dt 0 0 Z1 Zx = x+3=2 r;x(t)f (t)dt = t+1=2 f (t)dt;
= x+3=2
Z1
i dt Y f (t) t
0
0
(8.7.39)
and the result in (8.7.33) follows on di erentiation. So Theorem 8.29 is proved.
Corollary 8.29.1. Under the hypotheses of Theorem 8:29; there holds the formula Zx 0
t+1=2 f (t)dt = x+1=2
Z1 0
h
(xt)1=2 H+1 (xt) ; A (xt)
i dt Y f (t) t
(8.7.40)
for x > 0. The relation (8.7.40) leads to another inversion result for the transform Y .
Theorem 8.30. Let f 2 L;r and let either of the following assumptions hold: (a) 1 < r < 1; (r) 5 < 3=2 ; jRe()j and > 1=2 ; Re(); (b) r = 1; Re() 6= 0 and 1 5 5 3=2 ; jRe()j; (c) r = 1; Re() = 0 and 1 5 < 3=2. Then for almost all x > 0; d 2 x+3=2 f (x) = x;(+1=2) x1 dx
Z1 0
h
(xt)1=2 H+2 (xt) ; A+1 (xt)+1
i dt Y f (t) 2 : t
(8.7.41)
Proof. If f 2 C and satis es the hypotheses (a), (b) or (c), then by Corollary 8.29.1 0
the relation (8.7.40) holds for any x > 0. If we replace x by y; multiply both sides of the
298
Chapter 8. Bessel Type Integral Transforms on the Space L;r
obtained result by y; integrate from 0 to x in y and interchange the order of integration, direct calculations show that for f 2 C0 the relation 1 Z x t+1=2 (x2 ; t2 )f (t)dt 2 0 Z1 h i +3=2 (8.7.42) =x (xt)1=2 H+2 (xt) ; A+1 (xt)+1 Y f (t) dt t2 0 holds, if we take into account the formula Z
z H;1(z)dz = z H (z )
(8.7.43)
for the Struve function (8.7.27) (see Erdelyi, Magnus, Oberhettiger and Tricomi [2, 7.5(48)]). It is easily veri ed that for each x > 0; under the hypotheses of the theorem both sides of (8.7.42) represent bounded linear functionals on L;r ; and hence (8.7.42) is valid for f 2 L;r . Then by di erentiation of (8.7.42) twice, as in the proof of Theorem 8.29, we obtain the result in (8.7.41), and theorem is proved. The inversion of the transform Y in (8.7.1) in the limiting case = 1=2 ; Re( ) is given in terms of the integral in the Cauchy sense de ned in (8.4.24).
Theorem 8.31. Let 1 < r < 1 and ;1=2 < Re() 5 1=2 ; (r); where (r) is given in (3:3:9). If f 2 L1=2;;r ; then for almost all x > 0; d x+1=2 Z !1(xt)1=2H (xt)Y f (t) dt : (8.7.44) f (x) = x;(+1=2) dx +1 t 0 Proof. For real the result in (8.7.44) was proved by Heywood and Rooney [4, Theorem 5.3]. It is directly veri ed that their proof can be extended to complex . We only note that such a proof, which is more complicated than that in Theorem 8.29, is based on the representations of the form (8.7.28) and (8.7.33) for the characteristic function f1 of (1; 1) and for f2 = f ; f1 ; respectively, some auxiliary assertions and Theorem 8.27(d). Using the notation, similar to (8.4.24), Z1
we have the clear corollary:
!0
f (t)dt = lim !0
Z1
f (t)dt;
(8.7.45)
Corollary 8.31.1. If f 2 L = ;;r; where 1 < r < 1 and ;1=2 < Re() 5 1=2 ; (r);
then for almost all x > 0;
1 2
d x+1=2 f (x) = x;(+1=2) dx
Z1
!0
h
(xt)1=2 H+1 (xt) ; A (xt)
i dt Y f (t) : t
(8.7.46)
Remark 8.6. The results in (8.7.44) and (8.7.46) are formally similar to those in (8.7.28) and (8.7.33). But the integrals in these relations have di erent convergences, that is, the former is convergent in the Cauchy sense (8.4.24) and (8.7.45), while the latter is convergent in
299
8.8. The Struve Transform
the sense of L1(R+ ).
8.8. The Struve Transform We consider the integral transform H de ned by
H f (x) =
Z
1
0
(xt)1=2H (xt)f (t)dt (x > 0);
(8.8.1)
where H (z ) is the Struve function (8.7.27). First we show that the Struve transform H is represented via the Hankel transform H +1 in (8.1.1). Such a result is based on the following preliminary assertions.
Lemma 8.9. Let 1 < r < 1 and
3 1 1 1 s++ 2 ; 2 s;; 2 ; ( 2 C ; Re( ) > ;2): m (s) = 21 1 1 1 ; 2 s++ 2 ; 2 s;+ 2
(8.8.2)
(a) If > max[Re() + 1=2; ;Re() ; 3=2]; then there is a transform S 2 [L;r ] such that; for f 2 L;r ; 1 < r 5 2 and Re(s) = ; there holds
MS (s) = m (s) Mf (s):
(8.8.3)
If further > ;Re( ) ; 1=2; then the transform S is one-to-one on L;r into itself. (b) If < min[1=2 ; Re(); Re() + 5=2]; then there is a transform T 2 [L;r ] such that; for f 2 L;r ; 1 < r 5 2 and Re(s) = ; there holds
MT f (s) = m (1 ; s) Mf (s):
(8.8.4)
If further < Re( ) + 3=2; then the transform T is one-to-one on L;r into itself. (c) If f 2 L;r and g 2 L1;;r ; where > max[Re() + 1=2; ;Re() ; 3=2]; then 0
Z
0
1
S f (x)g (x)dx =
Z
0
1
f (x) T g (x)dx:
(8.8.5)
(d) If Re() > ;2; then for almost all x > 0;
T h+1;x (t) = x+3t;(+5=2)
Z
0
t +2 y H
(xy )dy;
(8.8.6)
where h+1;x (t) is given in (8.1.13). Proof. The rst assertion in (a) follows from Theorem 3.1, if we take m(s) = m (s); (m ) = max[Re() + 1=2; ;Re() ; 3=2] and (m ) = 1. Using (1.2.4) and (3.4.19), we nd jm ( + it)j 1 uniformly in (m ) < 1 5 5 2 < (m ) and m0 ( + it) = O(1=t) as jtj ! 1. To prove the one-to-one property of S on L;r ; we only note that 1=m (s) is holomorphic in the strip 1 (m ) < < 1(m ) with 1 (m ) = max[Re( ) ; 1=2; ;Re( ) ; 1=2] and 1 (m ) = 1.
300
Chapter 8. Bessel Type Integral Transforms on the Space L;r
If we put k (s) = m (1 ; s); then m 2 A implies k 2 A with (k ) = ;1 and (k) = 1 ; (m ); and (b) follows from (a). For r = 2 the result in (8.8.5) is proved similarly to that in Theorem 3.5(c), and it may be extended to any 1 < r < 1; since under the hypotheses of (c) both sides of (8.8.5) are bounded linear functionals on L;r L1;;r . To prove (d) we note that, since Re( ) > ;2; we can choose such that ;Re( ) ; 3=2 < < min[1; ;Re() + 1=2; Re() + 5=2]. Thus, by Lemma 8.1 and the assertion in (b), we have h+1;x 2 L;2 ; h+1;x = H +1g+1;x and T h+1;x 2 L;2. Hence, in accordance with (8.8.4) and (8.1.4) and by using (8.8.2), (8.7.8) and (2.1.6), we have for Re(s) = 0
MT h+1;x (s) = MT H +1 g+1;x (s) 3 1 +s+ 2 ; (Mg +1;x )(1 ; s) = m (1 ; s)2s;1=2 21 5 ; 2 ;s+ 2
3 1 1 1 ; 2 + s + 2 ; 2 ; ; s + 2 ;s+5=2 x = 2s;1=2 1 3 1 3 5 ; s + 2 ; 2 ; s + 2 ; 2 ; ; s + 2
3 sec 2 + s + 2 x;s+5=2 s ; 1 = 2 : =2 1 3 1 3 5 ; s + 2 ; 2 ; s + 2 ; 2 ; ; s + 2
(8.8.7)
Hence by (3.2.6),
T h+1;x (t) = x+5=2I (xt);
where
3 sec 2 + s + 2 1 ;s ds; s;1=2 z 2 I (z) = Rlim 1 3 1 3 5 !1 2i ; s + 2 ; 2 ; s + 2 ; 2 ; ; s + 2 ;iR
Z+iR
and the limit is taken in the topology of L;r . By closing the contour to the left, straightforward residue calculus (similar to that in the proof of Lemma 8.6) of the integrand at the simple poles s = ; ; 3=2 ; 2k (k = 0; 1; 2; ), by taking into consideration the assumption < ;Re( ) + 1=2; yields the result in (8.8.6). Thus Lemma 8.9 is proved. Now we study the representation of the Struve transform (8.8.1) via the Hankel transform (8.1.1)
Theorem 8.32. For 2 C (Re() > ;2) and f 2 C0; there holds H f = H +1 S f;
where the transform S is given in Lemma 8.9.
(8.8.8)
301
8.8. The Struve Transform
Proof. For all > max[Re() + 1=2; ;Re() ; 3=2] and f 2 C0; we nd S f 2 L;r by Lemma 8.9(a). Since Re( ) > ;2; there exists such that
1 3 1 5 < Re( ) + 5 ; > max Re() + 2 ; ;Re() ; 2 ; 2 2 and, according to Theorem 8.1(a), H +1 S f can be de ned. Lemma 8.1(b) assures h+1;x (t) 2 L1;;2 . Hence we can apply Theorem 8.1(d), and in accordance with (8.1.6) and (8.8.5) we have for almost all x > 0 Z 1 d ; ( +3 = 2) h ( t ) S f (t)dt H +1 S f (x) = x +1 ;x dx 0 d Z 1T h (t)f (t)dt: = x;(+3=2) dx +1;x 0 Then applying (8.8.6), we obtain for almost all x > 0 Z 1 Z d ;(+5=2) f (t)dt t y +2 H (xy )dy t H +1 S f (x) = x;(+3=2) x+3 dx 0 0 Z 1 Z xt d t;(+5=2) f (t)dt s+2 H (s)ds = x;(+3=2) dx 0 0
=
t
Z
0
(xt)1=2H (xt)f (t)dt = H f (x);
which completes the proof of the theorem. Now, as in the previous section, we present the results characterizing the boundedness, range and representation of the Struve transform (8.8.1) in L;r -space.
Theorem 8.33. Let 1 5 r 5 1 and let (r) be given in (3:3:9). (a) If 1 < r < 1; Re() + 1=2 < < Re() + 5=2 and = (r); then for all s = r such
that s0 = 1= and 1=s + 1=s0 = 1; H can be extended to L;r as an element of [L;r ; L1;;s ]. If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of (8:8:1) for Re(s) = 1 ; is given by 1 s ; 1 = 2 2 sec 2 s + + 2 Mf (1 ; s): (8.8.9) MH f (s) = 1 3 1 3 ; 2 ; s + 2 ; 2 ; ; s + 2 (b) If 1 < r < 1; jRe() + 1=2j < < Re() + 5=2 and = (r); then H is a one-to-one transform from L;r onto L1;;s ; and H (L;r ) = H +1 (L;r ):
(8.8.10)
Further; if jRe( ) + 1=2j < < Re( ) + 3=2; then H = H M;;1=2 H; M+1=2
(8.8.11)
H = ;M+1=2 H+ M;;1=2H :
(8.8.12)
and
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Chapter 8. Bessel Type Integral Transforms on the Space L;r
(c) If Re() + 1=2 5 5 Re() + 5=2 and = 1; then
2 [L;1; L1;;1]; and if Re( ) + 1=2 < < Re( ) + 5=2 and > 1; then for all r (1 5 r < 1); H 2 [L;1 ; L1;;r ]. (d) If f 2 L;r and g 2 L;s ; where 1 < r < 1 and 1 < s < 1 such that 1=r + 1=s = 1 H
and Re( )+1=2 < < Re( )+5=2 and = max[ (r); (s)]; then the following relation holds: Z
1
0
f (x) H g (x)dx =
Z
1
0
H f (x)g (x)dx:
(8.8.13)
(e) If f 2 L;r ; where 1 < r < 1 and Re() + 1=2 < < Re() + 5=2 and = (r); then
for almost all x > 0 the following relations hold: Z 1 d 1=2H (xt)f (t) dt ; ( xt ) H f (x) = x;;1=2 x+1=2 +1 dx t 0 if Re( ) > ;1; and d H f (x) = ;x;1=2 x1=2; dx 3
2
1
Z
0
(8.8.14)
(xt)1=2 64H;1 (xt) ; 6
21; (xt) 77 f (t) dt ; 5 t 1=2; + 21
(8.8.15)
if ;2 < Re( ) < 1: Proof. Since Re() > ;2; Theorem 8.32 implies H = H +1S on C0. Lemma 8.9(a) guarantees S 2 [L;r ] under > max[Re( )+1=2; ;Re( ) ; 3=2]. The case Re( )+1=2 5 ; Re( ) ; 3=2 occurs only if ;2 < Re() 5 ; 1 and for such that ;Re() ; 3=2 < 1=2 5 (r) 5 . Therefore for the value under consideration in (a), S 2 [L;r ]. Also, since (r) 5 < Re( ) + 5=2 by Theorem 8.1(a), H +1 2 [L;r ; L1;;s ] for all s = r such that s0 = 1= . Hence H +1 S 2 [L;r ; L1;;s ] for such s. Thus we can extend H on C0 to L;r by de ning it by (8.8.8) and then H 2 [L;r ; L1;;s ]. The relation (8.8.9) is proved directly by using (8.1.4) and (8.8.3). Thus (a) is proved. By Lemma 8.9(a), S 2 [L;r ] is one-to-one for > jRe( ) + 1=2j, and by Theorem 8.1(a), H +1 is one-to-one from L;r onto L1;;s for (r) 5 < Re( ) + 5=2. Then H = H +1 S is also one-to-one. Thus (8.8.10) holds. Under the hypotheses of (b), Lemma 3.1(i), Theorems 8.9(b) and 8.1(a) yield that H M;;1=2 H; M+1=2 maps L;r boundedly into L1;;s . Further, if f 2 L;r and 1=2 5 < Re( ) + 3=2; then by using (8.1.4), (3.3.14) and (8.3.13) for Re(s) = 1 ; we obtain the relation
MH M;;1=2 H; M+1=2 f (s)
s + + 1 2 2 Mf (1 ; s); = 1 ; 2 ; s + 23 ; 21 ; ; s + 23 2s;1=2 sec
which yields (8.8.11) according to (8.8.9). But both sides of (8.8.11) are in [L;r ; L1;;s ] if 1 < r < 1; Re( ) + 1=2 < < Re( ) + 3=2 and = (r); and hence we have the relation (8.8.11). Similarly (8.8.12) is shown.
303
8.8. The Struve Transform
(c) is proved similarly to Theorem 8.1(b) by using the asymptotic estimates for the Struve function (8.7.27) at zero and in nity: (z ! 0);
H (z ) = O(z +1 )
H (z ) = O(z ; min[1;Re();1=2])
(z ! 1)
(8.8.16)
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.5(55) and 7.5(63)]). The assertion (d) is also shown as in Theorem 8.1(c). To prove (e) we note that, if Re( ) > ;1; ;Re( ) ; 1=2 < 1=2 5 (r) 5 ; and hence by Lemma 8.1(a), g;x 2 L;r . Then from (8.8.13), if x > 0; we obtain 0
x
Z
0
t+1=2 H f (t)dt =
Z
1
0
g;x (t) H f (t)dt =
1
Z
0
H g;x (t)f (t)dt:
(8.8.17)
We evaluate (H g;x )(t) as in Lemma 8.9(d) by using the technique of the Mellin transform and residue theory. Namely, since g;x 2 L;2 , (8.8.9) and (8.7.8) imply for Re(s) = 1 ; 1 s ; 1 = 2 ; s +3 = 2 2 x sec 2 s + + 2 : MH g;x (s) = 1 7 1 3 ; 2 ; s + 2 ; 2 ; ; s + 2 Applying (3.2.6) and closing the contour to the left and calculating the residues of the integrand at the poles s = ; ; 2m ; 3=2 (m = 0; 1; 2; ) by noting that Re(s) = 1 ; < ;Re() + 1=2; we obtain 1 s ; 1 = 2 1 ; + iR 2 sec 2 s + + 2 1 lim Z ;s ds (xt) H g;x (t) = x+3=2 7 1 3 1 2i R!1 1; ;iR ; 2 ; s + 2 ; 2 ; ; s + 2 = x+1=2 (xt)1=2H+1 (xt) 1t : Thus the result in (8.8.14) follows on di erentiation. If Re( ) < 1; (8.8.15) is proved in a similar manner by using g;;x 2 L;r . Thus Theorem 8.33 is established. 0
In view of Theorems 8.2 and 8.33, we have
Corollary 8.33.1. Let 1 < r < 1; jRe()+ 1=2j < < Re() + 3=2 and = (r): Then H (L;r ) = M+1=2 H+ M ;; ;1=2 I ; ;;1=2 Fc L (r);r : (8.8.18) In particular, if jRe( ) + 1=2j < < Re( ) + 3=2 and = 1=2; H (L;2 ) = M+1=2H+ M ;;1 I ;1=2;;1=2Fc L2(R+ ) : (8.8.19)
Corollary 8.33.2. If 1 < r < 1; jRe() + 1=2j < < Re() + 3=2 and = (r); then the range H (L;r ) of the Hankel transform (8:1:1) is invariant under the operator M+1=2H+ M;;1=2.
304
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Proof. From relations (8.1.20), (8.8.10), (8.8.12) and (8.1.28), we have H (L;r ) = H +1 (L;r ) = H (L;r ) = (M+1=2H+ M;;1=2 H )(L;r ) = (M+1=2 H+ M;;1=2 ) H (L;r ) :
Remark 8.7. The exceptional value = ;Re() ; 1=2; for which H (L;r ) 6= H +1(L;r ); can only occur for ;3=2 < Re( ) 5 ; 1 since 1=2 5 (r) 5 < Re( ) + 5=2. Further, if Re( ) = ;1; then r = 2 and thus 3 1 2 R; 1 < r < 1; r 6= 2; ; 2 < < 2 :
H;1+i (L;r ) = H i (L;r )
In particular, H;1 (L;r ) = H 0(L;r )
3 1 1 < r < 1; r 6= 2; ; 2 < < 2 :
(8.8.20) (8.8.21)
Remark 8.8. Since on L1=2;2 = L2(R+ ); H2 = I (see Remark 8.1 in Section 8.1), then
H +1 (L2(R+ )) = L2 (R+ )
and in accordance with (8.8.10),
H L2 (R+ ) = L2(R+ ) (;2 < Re( ) < 0; Re( ) 6= ;1):
(8.8.22)
Theorems 8.28{8.31 show that the H -transform (8.8.1) is inverse to Y -transform (8.7.1). Moreover these transforms are inverse to each other. First we prove such a result for the space L1=2;2 = L2 (R+ ).
Theorem 8.34. If ;1 < Re() < 0; then on L1=2;2; H Y = Y H = I:
(8.8.23)
Proof. Since ;1 < Re() < 0; 1=2 < 3=2 + Re() = 3=2 ; jRe()j and Re() + 1=2 <
1=2 < Re( ) + 3=2. Then we can apply Theorems 8.27(b) and 8.33(b). Using (8.8.12) and (8.7.15), the equality H 2 = I being held on L1=2;2; and (8.3.15) and (8.3.4), we have H Y = ;M+1=2 H+ M;;1=2 H H M;1=2H+ M1=2;
= ;M+1=2 H+ M;1 H+ M1=2; = M+1=2M;;1=2 = I:
Thus the rst relation in (8.8.23) is valid. The second one is shown similarly by using (8.8.11) and (8.7.16). Theorem 8.28 in Section 8.7 is a considerable extension of the rst result in Theorem 8.34. The next result gives such an extension of the second one.
305
8.8. The Struve Transform
Theorem 8.35. Let 1 < r < 1 and jRe() + 1=2j < < min[1; Re() + 3=2] and = (r). For f 2 L;r and almost all x > 0; the inversion relation d x+1=2 f (x) = x;;1=2 dx
holds.
1
Z
0
(xt)1=2
#
"
+1 2 dt ;( + 1) H f (t) Y+1 (xt) + xt t
(8.8.24)
Proof. Since Re() + 1=2 < 1 and (r) 5 < Re() + 3=2; ;1 < Re() < 1=2; then
under the hypotheses of the theorem M1=2; Hf 2 L1=2;+Re();r; M;1=2h;x 2 L1=2+;Re();r in accordance with Theorem 8.33(a), Lemmas 3.1(i), 8.1(b) and 3.1(i). The assumption implies ;1 < (1=2) ; +Re() < 1 and therefore we can apply Theorem 8.9(c) to obtain from (8.3.5) the relation Z 1 M;1=2h;x (t) H+ M1=2; H f (t)dt 0
0
=;
1
Z
0
H; M;1=2h;x (t) M1=2; H f (t)dt:
(8.8.25)
From (8.8.12), (8.3.14) and (8.3.4) H+M1=2; H f = ;H+ M1=2;M+1=2H+M;;1=2H f
= ;M1 H; H+ M;;1=2 H f = M1=2; H f: (8.8.26) Substituting this and the relation (8.7.7) for (H; M;=2 h;x )(t) in (8.8.25) and using (8.1.13), we obtain Z 1 +1 = 2 x (xt)1=2J+1 (xt) H f (t) dtt 0
#
"
+1 2 dt ;( + 1) H f (t) ; Y+1 (xt) + xt t and the result in (8.8.24) follows from Theorem 8.3. This completes the proof of Theorem 8.35. Z 1 +1 = 2 =x (xt)1=2 0
In Theorem 8.35 the inversion formula for the transform H was proved for jRe( )+1=2j < < min[1; Re() + 3=2] and = (r). The result below gives a formula for the inverse of H in the nearly full range of boundedness of the transform.
Theorem 8.36. Let 1 5 r < 1; m 2 N and
Re( ) + 12 < < Re( ) + 25 ;
(r) 5 < m:
If f 2 L;r ; then for almost all x > 0; m d 1 +2m+3=2 ; m ; ; 5 = 2 f (x) = 2 x x dx x
Z
1
0
(xt)1=2[;m (xt) ; m;m+1 (xt)] H f (t)dt;
(8.8.27)
306
Chapter 8. Bessel Type Integral Transforms on the Space L;r
where
m mX ;1 x 2k;;m ;( + m ; k) : ;m(x) = x2 Y+m (x) + 1 k! k=0 2
(8.8.28)
;m (x) = x1=2[;m(x) ; m;m+1(x)]
(8.8.29)
"
#
Proof. The proof of this theorem is based on two preliminary assertions for two auxiliary
functions and
8
< t +5=2 x; ;2m;3=2 (x2 ; t2 )m;1 ; if 0 < t < x; 2 q;x(t) = ;(m) : 0; if t > x:
(8.8.30)
Lemma 8.10. Let 1=2 5 < m. (a) If jRe() + 1=2j < < Re() + 7=2; then ;m 2 L;r for 1 5 r < 1. (b) If jRe() + 1=2j < < Re() + 5=2; then for Re(s) = ;
1 1 3 ; 2 + s + 2 cot ; s + 7 : (8.8.31) M;m (s) = 2s;3=2 ; s + 2 ; 1 7 + ; s + 2m 2 2 2 2
Lemma 8.11. If jRe() + 1=2j < < Re() + 5=2 and 1=2 5 < m; then for almost all
x > 0;
H W1=x;m = q;x;
(8.8.32)
where the operator W is given in (3.3.12). For real Lemmas 8.10 and 8.11 were proved by Heywood and Rooney [4, Lemmas 6.3 and 6.4]. Their proofs are directly extended to complex . Using Lemmas 8.10 and 8.11 and taking the same arguments as in Theorems 8.29 and 8.30 with direct calculations, we obtain (8.8.27).
Remark 8.9. For m = 1 the result in Theorem 8.36 is an improvement of that in The-
orem 8.35, whereas < Re( ) + 3=2 is replaced by < Re( ) + 5=2. Also the hypothesis Re( ) > ;1 assures that ;[Re( ) + 1=2] < 1=2 5 .
Remark 8.10. When < Re()+3=2; direct calculation show that the inversion relation (8.8.27) is simpli ed by using only ;m : ;;5=2 1
f (x) = x 2m
d m x+2m+3=2 Z 1 (xt)1=2 (xt)H f (t)dt: ;m x dx 0
(8.8.33)
307
8.9. The Meijer K -Transform
8.9. The Meijer K -Transform We consider the integral transform, named the Meijer transform, for 2 C :
K f (x) =
Z
1
0
(xt)1=2K (xt)f (t)dt
(x > 0);
(8.9.1)
where K (z ) is the modi ed Bessel function of the third kind, or Macdonald function de ned by 1=2 W0;(2z ); K (z) = 2 sin( ) [I; (z ) ; I(z)] = 2z in terms of the modi ed Bessel function of the rst kind 2k + 1 X I (z) = e;i=2 J zei=2 = k!;(k +1 + 1) 2z k=0
(8.9.2) (8.9.3)
or the Whittaker function W0; (z ) in (7.2.2), for which see the book by Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2 (11)]. When = ;1=2; K;1=2(z ) = 1=2(2z );1=2e;z and hence the Meijer transform K;1=2 coincides with the Laplace transform (2.5.2) within a constant multiplier: 1=2 Z 1=2 1 ;xt e f ( t ) dt = Lf (x) (x > 0): (8.9.4) K;1=2f (x) = 2 2 0 The L;r -theory for the Meijer transform (8.9.1) is based on the Mellin transform of the kernel function x1=2K (x).
Lemma 8.12. If 2 C ; then for s 2 C with Re(s) > jRe()j ; 1=2; there holds s 1 1 ; + + ; ;+s Mx1=2K (x) (s) = 2;1 1=2 4 2 3 2 2s ; 4;2+2
s 1 1 ; ; + ; ++s : = 2;;1 1=2 4 2 3 2 2s ; 4+2+2
Proof. It is well known that
(8.9.5)
s ; s + (Re(s) > jRe( )j) (8.9.6) MK (x) (s) = 2 ; 2 ; 2 holds, for which see, for example, Prudnikov, Bruchkov and Marichev [2, 2.16.2.2]. Multiplying the numerator and the denominator of the left-hand side of (8.9.6) by ;([s ; ]=2 + 1=2) and using the Legendre duplication formula (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 1.2(15)]): 1 2z ;1 ;1=2 (8.9.7) ;(2z ) = 2 ;(z ); z + 2 ;
s;2
308
Chapter 8. Bessel Type Integral Transforms on the Space L;r
we have
s + ;(s ; ) ; MK (s) = 2;1 1=2 2s ; + 1 : ; 2
(8.9.8)
Applying the property (3.3.14) with = 1=2, we obtain
Mx1=2K (x) (s) = MM1=2K (s) = MK
s + 21
; 14 + 2 + 2s ; 21 ; + s ; = 2;1 1=2 ; 43 ; 2 + 2s
which gives the rst relation in (8.9.5). The second one is proved similarly if we multiply the numerator and the denominator in the right-hand side of (8.9.6) by ;[(s + )=2 + 1=2] and apply (8.9.7) and (3.3.14). Employing (8.9.5), we can apply the results in Chapters 3 and 4 to characterize the L;r 1= 2 properties of the Meijer transform (8.9.1). Indeed, by (8.9.5) and (1.1.2), Mx K (s) is an H-function of the forms 3 2 3 ; ; 1 7 6 4 2 2 1=2 ;1 1=2 2;0 6 s7 (8.9.9) Mx K (x) (s) = 2 H1;2 4 1 1 1 5 + ; ; ; ; 1 4 2 2 2 and 3 2 3 + ; 1 7 6 2 2 1=2 ; ;1 1=2 2;0 6 4 s7 : (8.9.10) Mx K (x) (s) = 2 H1;2 4 1 1 1 5 ; ; ; + ; 1 4 2 2 2 Hence in view of (3.1.5), the transform K is a special H -transform: 3 2 1 3 ; ; Z 1 7 6 7 f (t)dt (x > 0) (8.9.11) K f (x) = 2;1 1=2 H12;;20 64xt 14 2 21 1 5 0 4 + 2 ; 2 ; 2 ; ; 1 or 3 2 1 3 Z 1 + ; 7 6 7 f (t)dt (x > 0): (8.9.12) H12;;20 64xt 14 2 21 1 K f (x) = 2;;1 1=2 5 0 4 ; 2 ; 2 ; 2 + ; 1 By the notation in (3.4.1), (3.4.2), (1.1.7), (1.1.8), (1.1.10), (1.1.11) and (1.1.12), we have for the transform K in (8.9.11) or (8.9.12) that
309
8.9. The Meijer K -Transform
= jRe()j ; 21 ; = +1; a = = a1 = 1; a2 = 0; = ; 21 :
(8.9.13)
We denote by EH1 and EH2 the exceptional sets of two functions H21;;02(s) in (8.9.9) and in (8.9.10) (see De nition 3.4). Let < 3=2 ; jRe( )j. Then according to the property (1.3.3) of the gamma function, is not in the exceptional set EH1 ; if = 1 ; Re(s) such that (8.9.14) s 6= ; 2k ; 32 (k 2 N0) and is not in the exceptional set EH2 ; if = 1 ; Re(s) such that (8.9.15) s 6= ; ; 2m ; 23 (m 2 N0 ): Applying Theorems 3.6 and 3.7, we obtain the following results for the Meijer transform (8.9.1) in the space L;2 .
Theorem 8.37. Let 2 C and < 3=2 ; jRe()j. (i) There is a one-to-one transform K 2 [L; ; L ;; ] such that the relations 2
and
1
2
s 1 1 ; + + ; ;+s Mf (1 ; s) MK f (s) = 2;1 1=2 4 2 3 2 2s ; 4;2+2
(8.9.16)
1 ; + s ; 1 + + s ; Mf (1 ; s) MK f (s) = 2;;1 1=2 4 2 3 2 2s ; 4+2+2
(8.9.17)
hold for Re(s) = 1 ; and f 2 L;2 . If the condition (8:9:14) or (8:9:15) is valid; then the transform K maps L;2 onto L1;;2 . (ii) For f; g 2 L;2 there holds the relation 1
Z 0
K f (x)g (x)dx =
Z
1
0
f (x) K g (x)dx:
(8.9.18)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then K f is given by 2
+
d x(+1)=h dx 3 2 3 ; ; 1 (;; h); Z 1 7 6 7 f (t)dt H22;;31 64xt 1 14 21 2 5 0 + ; ; ; ; 1 ; ( ; ; 1 ; h ) 4 2 2 2 (x > 0)
K f (x) = 2;1 1=2hx1;(+1)=h
or
K f (x) = 2;;1 1=2hx1;(+1)=h
d x(+1)=h dx
(8.9.19)
310
Chapter 8. Bessel Type Integral Transforms on the Space L;r 3 1 3 Z 1 + ; ( ; ; h ) ; 7 6 7 f (t)dt H22;;31 64xt 1 14 21 2 5 0 ; ; ; + ; 1 ; ( ; ; 1 ; h ) 4 2 2 2 (x > 0): 2
(8.9.20)
If Re() < (1 ; )h ; 1; then
d (+1)=h dx x 3 2 3 ; ; 1 ; (;; h) Z 1 7 6 7 f (t)dt H23;;30 64xt 4 2 2 1 1 1 5 0 + ; ; ; ; 1 (; ; 1; h); 4 2 2 2 (x > 0)
(8.9.21)
d x(+1)=h dx 3 2 3 + ; 1 ; (;; h) Z 1 7 6 7 f (t)dt H23;;30 64xt 4 2 2 1 1 1 5 0 ; ; ; + ; 1 (; ; 1; h); 4 2 2 2 (x > 0):
(8.9.22)
K f (x) = ;2;1 1=2hx1;(+1)=h
or
K f (x) = ;2;;1 1=2hx1;(+1)=h
(iv) The transform K is independent of in the sense that, if 1 and 2 are such that i < 3=2 ; jRe()j (i = 1; 2) and if the transforms K;1 and K;2 are given on L1 ;2 and L2 ;2 ; T respectively; by (8:9:16) or (8:9:17); then K;1 f = K;2f for f 2 L1 ;2 L2 ;2 . (v) For f 2 L;2; K f is given in (8:9:1) and (8:9:11) or (8.9.12). Now we present the results on the boundedeness, range and representation of the Meijer transform (8.9.1) in the space L;r , for which we need two lemmas.
Lemma 8.13. The modi ed Bessel function of the third kind of complex order ; K (x);
has the following asymptotic estimates at zero:
K (x) 2;;1 ;(;)x (x ! +0; Re() < 0); K(x) 2;1 ;( )x; (x ! +0; Re() > 0); " # ; ( x= 2) ( x= 2) K (x) 2 sin( ) ;(1 ; ) ; ;(1 + ) (x ! +0; Re( ) = 0; 6= 0); K0(x) ; ; log x2 (x ! +0); and at in nity r K(x) 2x e;x (x ! +1);
(8.9.23) (8.9.24) (8.9.25) (8.9.26) (8.9.27)
311
8.9. The Meijer K -Transform
where = ; (1) is the Euler{Mascheroni constant (see Erdelyi, Magnus, Oberhettiger and Tricomi [1, 1.1(4) and 1.7(7)]). Proof. The estimates (8.9.23) and (8.9.24) follow from (8.9.2) if we take into account (7.2.3) and (7.2.4) for Re( ) > 0 and the relation (a; c; z ) = z 1;c (a ; c + 1; 2 ; c; z ) (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 6.5(6)]) and (7.2.3) and (7.2.4) when Re( ) < 0. The estimate (8.9.25), being clear by (8.9.2) and (8.9.3), yields (8.9.26) in the limiting case when ! 0. The asymptotic estimate (8.9.27) is the particular case of the relation given in Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.13(7)]. In the next lemma we treat two auxiliary functions g;x(t) given in (8.1.12) and h
i
h;x(t) = ;t;;3=2 (xt)+1 K+1(xt) ; 2 ;( + 1)
( 2 C ; Re( ) > 0):
(8.9.28)
We have
Lemma 8.14. Let 1 < r < 1 and Re() > 0. The following statements hold: (a) g;x(t) 2 L;r if and only if > ;Re() ; 1=2. (b) h;x(t) 2 L;r if and only if > Re() + 1=2. (c) Further; there holds the relation K g;x = h;x :
(8.9.29)
Proof. The assertion (a) was proved in Lemma 8.1(a). The statement (b) is proved
similarly to those in Lemma 8.1(b) on the basis of the asymptotic estimates (8.9.23), if we take into accout that by (8.9.2) and (8.9.3) the function z K (z ) is analytic for z 2 C . To prove (c), we use the property d hz +1 K (z )i = ;z +1 K (z ) (8.9.30) +1 dz (see Erdelyi, Magnus, Obrerhettinger and Tricomi [2, 7.11(21)]) and the asymptotic estimate (8.9.23), and we have
K g;x (t) =
1
Z 0
(t ) K (t )g;x( )d = 1=2
Z
x 0
(t )1=2K (t ) +1=2d
d [u+1K (u)]du +1 du 0 0 h i = ;t;;3=2 (xt)+1 K+1(xt) ; 2 ;( + 1) = h;x (t): = t;;3=2
Z
xt
u+1K (u)du = ;t;;3=2
Z
xt
Thus the relation (8.9.29) is proved, which completes the proof of Lemma 8.14.
Theorem 8.38. Let 2 C ; 1 5 r 5 s 5 1 and < 3=2 ; jRe()j. (a) The transform K de ned on L; can be extended to L;r as an element of [L;r ; L ;;s ]. 2
1
If either (i) 1 < r 5 2 or (ii) 1 < r < 1 and the conditions in (8:9:14) or in (8:9:15) are satis ed; then K is a one-to-one transform from L;r onto L1;;s . (b) If f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (8:9:18) holds. (c) For 5 3=2 ; jRe()j except when = 0 and = 3=2; K belongs to [L;1; L1;;1 ]. 0
312
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(d) Let 1 < r < 1; jRe()j = 1=2 and the condition (8:9:14) or (8:9:15) be satis ed.
Then
K (L;r ) = L(L;r ):
(8.9.31)
If neither (8:9:14) nor (8:9:15) is satis ed; then K (L;r ) is a subset of the right-hand side of (8:9:31); where L is the Laplace transform (2:5:2): Let jRe( )j < 1=2 and the condition (8:9:14) or (8:9:15) be satis ed. Then Re( )j K (L;r ) = K; (L;r ) = I;1=;12;;j L (L;r ); 1=2;jRe( )j 1;jRe( )j;1=2
(8.9.32)
)j where I;1=;12;;j1=Re( and L1;jRe()j;1=2 are the Erdelyi{Kober type operator (3:3:2) and the 2;jRe( )j generalized Laplace transform (3:3:3); respectively. If neither (8:9:14) nor (8:9:15) is satis ed; then K (L;r ) is a subset of the right-hand side of (8:9:32): (e) Let Re() > 0; 1 < r < 1 and ;1=2 ; Re() < < 3=2 ; Re(). If f 2 L;r ; then the relation Z 1 h i ;;1=2 (xt)+1 K+1 (xt) ; 2 ;( + 1) f (t) dt ; ;1=2 d t (8.9.33) K f (x) = ;x dx 0 t holds for almost all x > 0. Proof. The assertion (a) follows from Theorems 4.5(a) and Theorem 4.7(a), and (b) is derived from Theorem 4.5(b). The assertion (c) is proved similarly to the proof of Theorem 8.1(b) on the basis of the asymptotic behavior of K (x) established in Lemma 8.13. The assertion (d) follows from Theorem 4.7(b){(c), if we use the relation
K(z) = K; (z)
(8.9.34)
(see Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.2(14)]), which is also clear by (8.9.6). To prove (e) we employ Lemma 8.14 and Theorem 8.38(e). By Lemma 8.14(a), g;x 2 L;r ; and we can appply Theorem 8.38(c) 0
Z 0
x
t+1=2 K f (t)dt = =
Z 0 Z 0
1 1
g;x(t) K f (t)dt =
Z 0
1
K g;x (t)f (t)dt
h;x(t)f (t)dt
Z 1h i ; ; 3=2 = ;t (xt)1=2K+1 (xt) ; 2 ;( + 1) f (t)dt; 0
and the resullt in (8.9.33) follows on di erentiation. Thus Theorem 8.38 is proved.
Remark 8.11. The result in (8.9.31) shows that in the case jRe()j = 1=2 the range
K (L;r ) of the Meijer transform (8.9.1) coincides with the range L(L;r ) of the Laplace trans-
form (2.5.2).
313
8.10. Bessel Type Transforms
8.10. Bessel Type Transforms We consider the integral transforms
K f
Z
Z
(x) =
and
Lm f (x) =
with the kernels
Z (z ) = and
m) (z) = (
(
)
Z 0
1 Z (xt)f (t)dt 0
(x > 0)
1 (m) (xt)f (t)dt 0
1 ;1 z t exp ;t ; dt
t
(8.10.1)
(x > 0)
(8.10.2)
( 2 R+ ; 2 C )
(8.10.3)
(2 )(m;1)=2pm z m Z 1 (tm ; 1);1=me;zt dt 1 ; + 1 ; m1 m
(8.10.4)
1 m 2 N; 2 C ; Re() > m ; 1 being analytic functions of z 2 C for Re(z ) > 0. Particular cases of the functions Z (z ) and (n) (z ) coincide with the Macdonald function K (z ) (see Section 7.2.2 in Erdelyi, Magnus, Oberhettinger and Tricomi [2] and the previous Section 8.9). Namely, when = 1; z = t2 =4 and m = 2; then in accordance with the relation [2, 7.12(23)] Z 1 (8.10.5) K(z) = 12 exp ; 2z t + 1t t;;1 dt (Re(z ) > 0) 0 and the formula [2, 7.12(19)] Z 1 2 p 1 (t ; 1);;1=2 e;zt dt (8.10.6) ; 2 ; K (z ) = z2 1 Re(z ) > 0; Re( ) < 21 ; (8.10.3) and (8.10.4) take the forms ! 2 z 1 z (8.10.7) Z1 4 = 2 2 K; (z ) Re(z ) > 0; Re( ) > ; 2 and 1 2 (2) (8.10.8) (z ) = 2 z K; (z ) Re(z) > 0; Re() > ; 2 ; respectively. In these cases (8.10.1) and (8.10.2) are reduced to the Meijer type integral transform considered in the previous section. In particular, when m = 1 and = 1; (1) 1 (z ) = e;z and (8.10.2) is the Laplace transform (2.5.2):
L f (x) = (1) 1
Z 0
1 ;xt e f (t)dt Lf (x)
(x > 0):
(8.10.9)
314
Chapter 8. Bessel Type Integral Transforms on the Space L;r
The L;r -theory for the Bessel type transforms (8.10.1) and (8.10.2), as well as such a theory for the Meijer transform (8.9.1), is based on the Mellin transforms of the functions (8.10.3) and (8.10.4).
Lemma 8.15. Let 2 C . (a) If 2 R and Re(s) > ; min[0; Re()]; then +
+ s 1 (8.10.10) (s) = ;(s); : (b) If Re() > 1=m ; 1 and Re(s) > ; min[0; mRe()]; then s ;( m + s ); (2 )(m;1)=2 m : (8.10.11) M(m) (s) = m+1=2 1 m ; + 1 ; m + ms Proof. (8.10.10) and (8.10.11) are proved directly by applying (2.5.1) to (8.10.3) and (8.10.4) by virtue of properties of the gamma and beta functions (see Erdelyi, Magnus, Oberhettinger and Tricomi [1, 1.1(1), 1.5(1) and 1.5(5)]).
MZ
Now we can apply the results in Chapters 3 and 4 to characterize L;r -properties of the Bessel type transforms (8.10.1) and (8.10.2). According to (8.10.10) and (8.10.11) and (1.1.2), (m) MZ (s) and M )(s) are H-functions of the form 2
MZ (s) =
and
1 H2;0 6 0;2 4 (0; 1); ; 1
3 7 5
s
(8.10.12)
1 ; 1 3 + 1 ; 7 6 (2 )(m;1)=2 s7 ; m m (8.10.13) M(m))(s) = m+1=2 H21;;02 64 5 1 m (m; 1); 0; m respectively. Hence in accordance with (3.1.5), the transform K in (8.10.1) and the transform L(m) in (8.10.2) are special H -transforms in (3.1.1): 2
K f (x) = 1
and
Z 0
1
2
H02;;20 64xt
3
7 5 f (t)dt 1 (0; 1); ;
(8.10.14)
1; 1 3 + 1 ; 7 m m 7 : (8.10.15) L(m)f (x) = 5 1 ( m; 1) ; 0 ; m According to (3.4.1), (3.4.2), (1.1.7), (1.1.8), (1.1.10), (1.1.11) and (1.1.12) we have (8.10.16) = ; min[0; Re()]; = +1; a = = a1 = 1 + 1 ; a2 = 0; = ;1 + 2
(2 ) m;1)=2 Z 1 H 2;0 66xt mm+1=2 0 1;2 4 (
315
8.10. Bessel Type Transforms
for the H-function in (8.10.12) and = ; min[0; mRe()]; = +1; a = = a1 = 1; a2 = 0; (8.10.17) = (m ; 1) + m1 ; 23 for the H-function in (8.10.13). Let EH1 and EH2 be the exceptional sets of the H-functions in (8.10.12) and (8.10.13) (see De nition 3.4 in Section 3.6). According to (8.10.10) and (8.10.12) the set EH1 is empty (because the gamma function ;(z ) is not equal to zero), while by (8.10.11) and (8.10.13) is not in the exceptional set EH2 ; if
s 6= 1 ; m( + 1 + k) (k = 0; ;1; ;2; ; Re(s) = 1 ; ):
(8.10.18)
Applying Theorems 3.6 and 3.7 in Section 3.6, we obtain the following results for the Bessel type transforms (8.10.1) and (8.10.2) in the space L;2 .
Theorem 8.39. Let 2 R ; 2 C and be such that < 1 + min[0; Re()]. (i) There is a one-to-one transform K 2 [L; ; L ;; ] such that the relation +
2
1 holds for Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then
MK f )(s) = ;(s);
+s
1
2
Mf (1 ; s)
Z 1 1 g (x)dx: K f ( x ) g ( x ) dx = f ( x ) K 0 0
Z
(8.10.19)
(8.10.20)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then Kf is given by 2
+
d x(+1)=h dx 3 2 (;; h) Z 1 7 (x > 0): (8.10.21) H12;;31 64xt 5 f (t)dt 1 0 ; ; ( ; ; 1 ; h ) (0; 1); If Re() < (1 ; )h ; 1; then K f (x) = ; h x1;(+1)=h dxd x(+1)=h 3 2 (;; h) Z 1 7 (x > 0): (8.10.22) H13;;30 64xt 5 f (t)dt 1 0 ; (; ; 1; h); (0; 1); (iv) K is independent of in the sense that if and e are such that max[; e] < 1 + min[0; Re( )] and if the transforms K and Ke are given in (8:10:19); then K f = Ke f T for f 2 L;2 Le ;2 . (v) K f is given in (8:10:1) and (8:10:14) for f 2 L;2.
K f (x) = h x ;
=h
1 ( +1)
316
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Theorem 8.40. Let m 2 N and let 2 C be such that Re() > 1=m ; 1 and <
1 + min[0; mRe( )]. (i) There is a one-to-one transform L(m) 2 [L;2; L1;;2] such that the relation s (2 )(m;1)=2 ;(m + s); m Mf (1 ; s) (8.10.23) ML(m) f (s) = m+1=2 s 1 m ; +1; m + m holds for Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then Z 1 1 (m) L f (x)g (x)dx = f (x) L(m) g (x)dx: 0 0
Z
(8.10.24)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then Lm f is given by 2
(
)
)
m;1)=2 d x(+1)=h hx1;(+1)=h dx +1=2
Lm f (x) = (2m)n
(
+
(
3 1 1 (;; h); + 1 ; m ; m 1 2;1 6 7 7 f (t)dt (x > 0): (8.10.25) H2;3 64xt 5 1 0 (m; 1); 0; m ; (; ; 1; h)
2
Z
If Re() < (1 ; )h ; 1; then )(m;1)=2 hx1;(+1)=h d x(+1)=h L(m)f (x) = ; (2mm +1=2 dx 2 1 ; 1 ; (;; h) 3 Z 1 + 1 ; 7 6 m m 7 f (t)dt (x > 0): (8.10.26) H23;;30 64xt 5 1 0 (; ; 1; h); (m; 1); 0; m (iv) L(m) is independent of in the sense that if and e are such that max[; e] < 1 + min[0; mRe( )] and if the transforms L(m) and Le (m) are given in (8:10:23) on L;2 and T Le ;2; respectively; then L(m) f = Le (m) f for f 2 L;2 Le ;2 . (v) L(m)f is given in (8:10:2) and (8:10:15) for f 2 L;2.
Corollary 8.40.1 Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then the
Laplace transform Lf is given by
Lf
2
+
d x(+1)=h (x) = hx1;(+1)=h dx
# (;; h) H xt f (t)dt (x > 0); 0 (0; 1); (; ; 1; h) while if Re() < (1 ; )h ; 1; then d Lf (x) = ;hx1;(+1)=h x(+1)=h dx " # Z 1 (;; h) 2;0 H1;2 xt f (t)dt (x > 0): 0 (; ; 1; h); (0; 1) Z
1
; ;
11 12
"
(8.10.27)
(8.10.28)
317
8.10. Bessel Type Transforms
Proof. The corollary follows from Theorem 8.40(c) if we take into account (8.10.9) and
Property 2.2 of the H -function in Section 2.1.
Now we present the L;r -theory of the Bessel type transforms K and L(m) . First we characterize the boundedeness, range and representation of the Bessel type transform (8.10.1).
Theorem 8.41. Let 2 R ; 2 C and < 1 + min[0; Re()]. (a) If 1 5 r 5 s 5 1; then the transform K de ned on L; can be extended to L;r as an element of [L;r ; L ;;s ]. When 1 5 r 5 2; then K is a one-to-one transform from L;r +
2
1
onto L1;;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (8:10:20) holds. (c) Let 1 < r < 1 and let I; ;; and Lk; be the Erdelyi{Kober type operator (3:1:1) and the generalized Laplace operator (3:3:3); respectively. Then 0
K (L;r ) = L
( +1)
=;(;2)=2(+1)(L;r );
(8.10.29)
if Re( ) 5 ; 1=2 or Re( ) = =2;
K (L;r ) = I;==;=
; L1+1=;0 (L;r );
1 2 ; ( +1) 0
(8.10.30)
if 0 5 Re( ) < =2; and
K (L;r ) = I;==;=
=)Re() L (L;r ); 1+1 =; ; Re( ) =)Re()
1 2 +(1+1 ; ( +1) (1+1
;
(8.10.31)
if ;1=2 < Re( ) < 0. (d) If f 2 L;r ; where 1 < r < 1 and 0 < < 1; and Re() > 0; then for almost all x > 0 the following relation holds: Z 1 1 + 1 d +1 (8.10.32) K f (x) = ; dx 0 Z (xt) ; ; f (t) dtt : Proof. The assertion (a) follows from Theorems 4.5(a). The assertions (b) and (c) follow from Theorem 4.5(b) and Theorem 4.7(b)(c), respectively, with ! = = ; (1 + 1=) min[0; Re( )] ; 1=2 in the latter. To prove (d) we need preliminary results for two auxiliary functions of the forms
x (t) = and
(
1; if 0 < t < x; 0; if t > x;
h;x(t) = 1t Z+1(xt) ; 1 ; + 1 :
(8.10.33)
(8.10.34)
Lemma 8.16. Let 1 < r < 1; 2 R and 2 C . The following statements hold. (a) x(t) 2 L;r if and only if > 0. +
318
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(b) h;x(t) 2 L;r if and only if > 0 for Re() > ;1; > 1 for Re() = ;1 and
Im( ) 6= ;1 or = ;1; and > ;Re( ) for Re( ) < ;1. (c) Further; if Re() > 0; then
K x (t) = ;h;x(t):
(8.10.35)
Proof. The assertions (a) and (b) are proved similarly to those in Lemma 8.1(a)(b) on
the basis of the asymptotic estimates of Z (x) at zero and in nity (Kratzel [5]): 8 1; ; > > if Re( ) > 0; > > > > > > > > > > 1 ; + ;(; )x ; if Re( ) = 0; Im( ) 6= 0; > < Z (x) > > > > > > > > > > > > > :
; log x;
if = 0;
;(; )x ;
if Re( ) < 0
(8.10.36)
as x ! +0; and h
i
Z (x) x(2;)=(2+2) exp ; x=(+1) ;
(8.10.37)
1=(+1) 1 2 ; (2 +1)=(2+2) ; = 1+ ; with = + 1 as x ! +1. Further we note the formula in Kilbas and Shlapakov [2, (22)] m (8.10.38) ; dzd Z (z) = Z;m (z) (m = 1; 2; ): Taking into account the rst asymptotic estimate in (8.10.36) and the relation (8.10.34), we have
K x
(t) =
1 Z (t ) x ( )d 0
Z
=
Z
0
x
Z()(t )d
d Z +1 (u)du du 0 0 = ; 1t Z+1 (xt) ; 1 ; + 1 = ;h;x (t); and thus (8.10.35) is shown, which completes the proof of Lemma 8.16. = 1t
Z
xt
Z (u)du = 1t
Z
xt
Returning to the proof of the assertion (d) of Theorem 8.41, we nd from Lemma 8.16(a) that x 2 L;r and we can appply Theorem 8.41(b) with s = r. Then (8.10.33), (8.10.20), (8.10.35), (8.10.38) (with m = 1) and (8.10.34) yield 0
Z 0
Z 1 Z 1 x K f (t)dt = x(t) K f (t)dt = K x (t)f (t)dt 0
=;
1
Z 0
0
h;x(t)f (t)dt = ;
1 1 +1 + 1 1 f (t)dt; t Z (xt) ; ; 0
Z
319
8.10. Bessel Type Transforms
and the resullt in (8.10.32) follows on di erentiation. Thus Theorem 8.41 is proved. Now we present the results characterizing the boundedeness and the range of the Bessel type transform (8.10.2) in the space L;r .
Theorem 8.42. Let m 2 N; Re() > 1=m ; 1; and < 1 + min[0; mRe()]. (a) If 1 5 r 5 s 5 1; then the transform Lm de ned on L; can be extended to L;r (
)
2
as an element of [L;r ; L1;;s ]. If 1 5 r 5 2 or if 1 < r < 1 and the condition (8:10:18) is satis ed; then L(m) is a one-to-one transform from L;r onto L1;;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (8:10:24) holds. (c) Let 1 < r < 1 and let I; ;; and Lk; be the Erdelyi{Kober type operator (3:1:1) and the generalized Laplace operator (3:3:3); respectively. If the condition (8:10:18) is satis ed; then 0
Lm (L;r ) = L ; (
)
;m)(;1=m)(L;r );
(8.10.39)
1 (1
if Re( ) = 1=m;
Lm (L;r ) = I; ;;m (
)
(1 )( ;1 0
;1=m)L
;
10
(L;r );
(8.10.40)
if 0 5 Re( ) < 1=m; and
Lm (L;r ) = I; (
)
; =m ;m L1;;m (L;r );
(8.10.41)
+1 1 ;1
if 1=m ; 1 < Re( ) < 0. If the condition (8:10:18) is not satis ed; then L(m) (L;r ) is a subset of the right-hand sides of (8:10:39); (8:10:40) and (8:10:41) in the cases when Re( ) = 1=m; 0 5 Re( ) < 1=m and 1=m ; 1 < Re( ) < 0; respectively. (d) If f 2 L;r ; where 1 < r < 1 and > m ; 1; and Re() > 0; then for almost all x > 0 the following relation holds:
Lm) f (
;2 k dt : x 1;m d Z 1 (m) (xt)f (t) ; mY ; + 1 + (x) = ; m dx 0 +1 m tm k=0
"
#
(8.10.42)
Proof. The assertions (a), (b) and (c) follow from Theorems 4.5 and Theorem 4.7 with ! = (m ; 1) + 1=m ; 1 ; min[0; mRe()]. In order to show (d) we prepare a lemma for the auxiliary functions: ( tm;1 ; if 0 < t < x; gm;x(t) = (8.10.43) 0; if t > x and " # mY ;2 k (m) m ; 1 ;m (8.10.44) h;x(t) = m t +1 (xt) ; ; + 1 + m : k=0
320
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Lemma 8.17. Let 1 < r < 1; m = 2; 3; and Re() > 1=m ; 1. Then the following
statements hold: (a) gm;x(t) 2 L;r if and only if > 1 ; m. (b) h;x(t) 2 L;r if and only if > m ; 1. (c) Further,
Lm gm;x (t) = ;h;x(t): (
)
(8.10.45)
Proof. The assertions (a) and (b) are proved similarly to those in Lemma 8.1(a),(b) on the basis of the asymptotic estimates of (m)(x) at zero and in nity (see Kratzel [1, (8a) and (7)]): (m)(x) A with A =
mY ;2
k (Re() > 0) ; + m k=0
as x ! +0; and
(m)(x) Bx(m;1);1+1=me;x ;
(8.10.46)
B = (2 )(m;1)=2m(1;m)+1=2;1=m
(8.10.47)
as x ! +1 (see Kratzel [1, x 3]). To prove (c), by using the formula in Kratzel [1, (5)] d (m)(z) = ; z m;1 (m) (z); (8.10.48) ;1 dz m and by the asymptotic estimate (8.10.46) and the relation (8.10.44), we have
Lm)gm;x (
(t) =
Z
1 (m) (t )gm;x( )d 0
= t;m
Z
=
x (m) (t ) m;1d
Z 0
Z xt xt (m) d h(m) (u)idu (u)um;1du = ;mm;1 t;m du +1
0
0
h
i
= ;mm;1 t;m (m+1) (xt) ; A+1 = ;h;x (t); and (8.10.45) is proved as well as Lemma 8.17.
Thus the assertion (d) of Theorem 8.42 follows. In fact, by Lemma 8.17(a), we have gm;x 2 L;r ; and we can appply Theorem 8.42(b) with s = r. Using (8.10.43), (8.10.24), (8.10.45), (8.10.48) and (8.10.44), we have 0
x
Z 0
tm;1 L(m)f (t)dt =
1
Z 0
=;
1
Z 0
gm;x(t) L(m) f (t)dt =
Z
1 (m) L g (t)f (t)dt m;x 0
h;x(t)f (t)dt
= ;mm;1
1
Z 0
"
m+1) (xt) ; (
mY ;2
#
k f (t) dt ; ; +1+ m tm k=0
and after di erentiation we obtain (8.10.42). This completes the proof of Theorem 8.42.
321
8.11. The Modi ed Bessel Type Transform
8.11. The Modi ed Bessel Type Transform We consider the integral transform
L; f
with the kernel ) (z ) = (;
( )
(x) =
Z
1 ( ) ;(xt)f (t)dt 0
(x > 0)
(8.11.1)
Z 1 (t ; 1);1= t e;zt dt 1 1 ; +1;
(8.11.2)
> 0; 2 R; Re() > 1 ; 1
being an analytic function of z 2 C for Re(z ) > 0. When = 0; Z 1 ( ) (t ; 1);1= e;zt dt ;0 (z) = 1 1 ; +1;
(8.11.3)
1 > 0; Re() > ; 1 and, hence, for = m 2 N the transform (8.11.1) is reduced to the transform (8.10.2):
L;m f (x) = (2) ;m = mm = x;m Lm tm f (x): (8.11.4) is called the modi ed Bessel type transform. We note that, when = 0 So, the transform L;
(
) 0
(1
) 2
+1 2
(
)
( )
and = 2; by the relation (8.10.8), (8.11.1) is the Meijer type transform discussed in Section 8.9. The L;r -theory of the modi ed Bessel type transform (8.11.1) is based on the Mellin transform of the function (8.11.2). The following lemma can be obtained similarly to Lemma 8.15.
Lemma 8.18. Let > 0; 2 R; and Re(s) > max[0; Re() + ]. Then s ;(s); ; ; + ) (s) = M(; 1 + s : ; 1; +
(8.11.5)
Now we characterize the L;r -properties of the modi ed Bessel type transform (8.11.1). ) (t) in (8.11.5) is written as The Mellin transform of (; 3 2 1 + 1 1; ; 7 6 2 ; 0 ( ) s7 ; 6 (8.11.6) M; (s) = H1;2 4 5 1 (0; 1); ; ; ;
322
Chapter 8. Bessel Type Integral Transforms on the Space L;r
) is a special H -transform: and hence the transform L(; 3 2 1 + 1 Z 1; ; 7 7 f (t)dt (x > 0): (8.11.7) L(; )f (x) = 01 H12;;20 664xt 5 1 ; (0 ; 1) ; ; ; The parameters de ned in (3.4.1), (3.4.2), (1.1.7), (1.1.8), (1.1.10), (1.1.11) and (1.1.12) are given with the sux 0 in the forms 0 = max[0; Re() + ]; 0 = +1; (8.11.8) a0 = 0 = a1;0 = 1; a2;0 = 0; 0 = 1 ; ; 23 for the function H21;;02(s) in (8.11.6). Let EH be the exceptional set of this function (cf. De nition 3.4). Then is not in the exceptional set EH ; if 6= k ; (k 2 N): (8.11.9) Applying Theorems 3.6 and 3.7, we obtain the following results for the modi ed Bessel type transform (8.11.1) in the space L;2 .
Theorem 8.43. Let > 0; 2
R
and Re( ) > 1= ; 1 be such that < 1 ;
max[0; Re( ) + ]. (i) There is a one-to-one transform L(; ) 2 [L;2; L1;;2] such that the relation + s ;( s ); ; ; Mf (1 ; s) ) f (s) = (8.11.10) ML(; 1+ s ; 1; + holds for Re(s) = 1 ; and f 2 L;2 . (ii) If f; g 2 L;2; then Z 1 ( ) 1 ) g (x)dx: f ( x ) g ( x ) dx = f (x) (; ; 0 0
Z
L
L
(8.11.11)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then L; f is given by 2
L; f
( )
+
( )
d x(+1)=h (x) = hx1;(+1)=h dx
3 1 + 1 Z 1 (;; h); 1 ; ; 7 6 7 f (t)dt (x > 0): (8.11.12) H22;;31 64xt 5 1 0 (0; 1); ; ; ; ; (; ; 1; h) 2
When Re() < (1 ; )h ; 1;
L; f
( )
d x(+1)=h (x) = ;hx1;(+1)=h dx
3 1 + 1 1 ; ; ; (;; h) 1 3;0 6 7 7 f (t)dt (x > 0): (8.11.13) H2;3 64xt 5 1 0 (; ; 1; h); (0; 1); ; ; ; 2
Z
323
8.11. The Modi ed Bessel Type Transform
(iv) L; is independent of in the sense that; if and are such that max[; ] < ( )
e
e
) and L are given on L;2 and L ; 1 ; max[0; Re( ) + ] and if the transforms L(; e ;2 T ( ) )f = L e respectively in (8:11:10); then L(; f for f 2 L L . ;2 ; ;2 e ( ) (v) L; f is given in (8:11:1) and (8:11:7) for f 2 L;2. e ;
( )
Now we proceed to characterize the mapping properties of the modi ed Bessel type transform (8.11.1) in the space L;r owing to Theorems 4.5 and 4.7. First we prepare a lemma on the characteristic function x (t) in (8.10.33) and 3 2 ; 1 ; ; ; 7 6 ) 7: (8.11.14) ( xt ) ; g;x(t) = 1t 64(; ;1 5 ; 1;
Lemma 8.19. Let 1 < r < 1 and let > 0; 2 C and 2 C be such that 1= ; 1 <
Re( ) < (1 ; )= . Then the following statements hold: (a) x(t) 2 L;r if and only if > 0. (b) g;x(t) 2 L;r if and only if > 0. (c) Further, L(; ) x = ;g;x: (8.11.15) Proof. The assertion (a) coincides with that in Lemma 8.15(a). (b) is proved similarly to )(x) at zero and in nity that in Lemma 8.1(b) on the basis of the asymptotic estimates of (; (see Glaeske, Kilbas and Saigo [1]): ; ; ; )(x) A with A = for Re( ) < ; (8.11.16) (; + 1 ; 1; as x ! +0; and ) (z ) Be;x x(1= );;1 with B = +1;1= for Re( ) > 1 ; 1 (8.11.17) (; as x ! +1. As for (c), using the directly veri ed relation d m ( )(z) = (;1)m( ) (z ) (m = 1; 2; ) (8.11.18) ; ;+m dz and the asymptotic estimate (8.11.16), we have
L; x (t) = ( )
Z
Z x 1 ( ) ) (t )d ; (t ) x( )d = (; 0 0
Z xt Z xt 1 d ( ) (u)du 1 ( ) ; (u)du = ; t =t du ;;1 0 0 3 2 ; 1 ; ; ; 7 6 ) 7: ( xt ) ; = ; 1t 64(; ;1 5 ; 1;
324
Chapter 8. Bessel Type Integral Transforms on the Space L;r
So the relation (8.11.15) is proved as well as Lemma 8.19. ). Now we can state the L;r -theory of the transform L(;
Theorem 8.44. Let > 0; 2 R and 2 C be such that Re() > 1= ; 1 and
< 1 ; max[0; Re() + ]. (a) If 1 5 r 5 s 5 1; then the transform L(; ) de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ]. If 1 5 r 5 2 or if 1 < r < 1 and the condition in (8:11:9) is ) is a one-to-one transform from L;r onto L1;;s . satis ed; then L(; (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (8:11:11) holds. (c) Let 1 < r < 1 and ! = max[0; Re()+ ] ; ; 1 + 1= : If the condition in (8:11:9) is satis ed; then 0
L; (L;r ) = L ; ;! (L;r ); ( )
when Re(! ) = 0; and
1
L; (L;r ) = ( )
(8.11.19)
0
I;;;1! ;; 0 L1; 0 (L;r );
(8.11.20)
when Re(! ) < 0; where 0 is given in (8:11:8). If the condition (8:11:9) is not satis ed; then L(; ) (L;r ) is a subset of the right-hand sides of (8:11:19) and (8:11:20) in the respective cases when Re(! ) = 0 and Re(! ) < 0. (d) Let 1 < r < 1; > 0 and Re() < (1 ; )= ; then for f 2 L;r the relation 2 ; 13 Z ; ; ; (8.11.21) L(; )f (x) = ; dxd 01 664 ;;1(xt) ; 775 f (t) dtt ; 1; holds for almost all x > 0. Proof. The assertion (a){(c) can be obtained by appealing to Theorems 4.5 and 4.7. For the assertion (d), since > 0 and by Lemma 8.19(a), x 2 L;r and we can apply Theorem 8.44(b) with s = r. Using (8.10.33), (8.11.11), (8.11.15) and (8.11.14), we have 0
Z 0
x
L
; f ( )
(t)dt = =
1
Z 0
Z
x (t)
L; f
( )
(t)dt
Z 1 1 ( ) g;x (t)f (t)dt ; x (t)f (t)dt = ; 0 0
L
1 ; ; ; ; 1 1 6 ( ) 77 f (t)dt; 6 ( xt ) ; =; ; ; 1 5 t4 0 ; 1 ; and the resullt in (8.11.21) follows on di erentiation. Theorem 8.44 is proved. 2
Z
3
325
8.12. The Generalized Hardy{Titchmarsh Transform
8.12. The Generalized Hardy{Titchmarsh Transform Let a; b; c; ! 2 C with Re(a) > 0. We consider the integral transform ;
Ja;b;c;! f
(x) =
1
Z
0
Ja;b;c;! (xt)f (t)dt (x > 0)
with the kernel ;(a) z ! F a; b; c; ; z 2 Ja;b;c;! (z ) = ;(b);(c) 1 2 4
!
(8.12.1) (8.12.2)
containing the hypergeometric function 1 F2 (a; b; c; x). When a p = 1; b = 3=2 and c = ! = +3=2; then in accordance with (8.7.27) J1;3=2;3=2;+3=2(z ) = 2+1 z H (z ) and this transform coincides with the transform H in (8.8.1) (apart from the constant multiplication factor 2+1 ):
J1;3=2;+3=2;+3=2f
(x) = 2+1 H f (x):
(8.12.3)
If a = 1; b = + 1; c = + + 1 and ! = 2 + + 1=2; (8.12.2) takes the form
p
J1;+1;++1;2++1=2 (z ) = 2+2 zJ; (z );
(8.12.4)
where J; (z ) is the Lommel function 1 X
+2k+2 k z ( ; 1) J; (z ) = ;(1 + + k);(1 + + + k) 2 k=0 2;2 ; = ;(2);( + ) s2+;1; (z )
(8.12.5)
with ; 2 C (Re( ) > ;1; Re( + ) > ;1); where for the function s; (z ) one may refer to Erdelyi, Magnus, Oberhettinger and Tricomi [2, 7.5(69)]. The transform with such a kernel function ;
J; f
(x) =
1
Z
0
(xt)1=2J; (xt)f (t)dt (x > 0)
(8.12.6)
is known as the modi ed Hardy transform. When a = + + 1=2; b = + + 1 and c = ! = + 2 + 1; (8.12.1) is known as the transform given by Titchmarsh [2]. This transform as well as (8.12.3) and (8.12.4) are particular cases of the more general transform (8.12.1) with ! = b + c ; a ; 1=2; indicated by Titchmarsh [3, Section 8.4, Example 3]. Therefore we call the transform (8.12.1) the generalized Hardy{Titchmarsh transform. When = = 0; 1; 2; ; then the modi ed Hardy transform (8.12.6) coincides with the extended Hankel transform (8.4.1) (apart from the constant multiplication factor (;1)l): l
J;l f
(x) = (;1)l
H l f
(x):
(8.12.7)
In particular, when = 0; the Lommel function J;0(z ) in (8.12.5) coincides with the Bessel function J (z ); and then the modi ed Hardy transform (8.12.6) reduces to the Hankel transform (8.1.1):
J;0f
(x) =
H f
(x):
(8.12.8)
326
Chapter 8. Bessel Type Integral Transforms on the Space L;r
The L;r -theory of the generalized Hardy{Titchmarsh transform (8.12.1) and of the modi ed Hardy transform (8.12.6) are based on the Mellin transforms of the function Ja;b;c;! (x) and x1=2J; (x) in (8.12.2) and (8.12.5), respectively.
Lemma 8.20. (a) Let a; b; c; ! 2 C (a 6= 0; ;1; ) and s 2 C be such that 0 < Re(! + s) < 2Re(a); Re(! + s) < 21 + Re(b + c ; a):
Then
(8.12.9)
;(! + s); a ; !2 ; 2s MJa;b;c;! (x) (s) = 1=2 1 ! s ! s ! s : ; 2 + 2 + 2 ; b; 2 ; 2 ; c; 2 ; 2
(8.12.10)
(b) Let ; 2 C (Re() > ;1; Re( + ) > ;1) and s 2 C be such that Then
; 12 ; Re( + 2) < Re(s) < 23 ; Re( + 2); Re(s) < 1:
(8.12.11)
M[x1=2J; (x)] (s) ; 12 + + 2 + s ; 43 ; 2 ; ; 2s = 2;;2 1=2 3 s 3 s 3 s : ; 4 + 2 ++ 2 ; 4 ; 2 ; 2 ; 4 + 2 ; 2
(8.12.12)
Proof. It is known (see, for example, Prudnikov, Brychkov and Marichev [3, 8.4.48.1])
that the Mellin transform of the hypergeometric function 1F2 (a; b; c; ;x) is given by b);(c) ;(s);(a ; c) ; (8.12.13) M 1 F2 (a; b; c; ;x) (s) = ;(;( a) ;(b ; s);(c ; s) provided that (8.12.14) 0 < Re(s) < Re(a); Re(s) < 14 + Re(b +2 c ; a) (b; c 6= 0; ;1; ;2; ): Using the elementary operators M ; W and Na ; in (3.3.11), (3.3.12) and (8.5.7), we may represent the function Ja;b;c;! (x) in (8.12.2) in the form ;(a) M W N n F (a; b; c; ;x)o: (8.12.15) Ja;b;c;! (x) = ;(b);(c) ! 2 2 1 2 Applying (3.3.14), (3.3.15) and (8.5.9), we have n oi a) h M M! W2 N2 1 F2 (a; b; c; ;x) (s) MJa;b;c;! (x) (s) = ;(;( b);(c) n oi a) h M W2 N2 1F2 (a; b; c; ;x) (s + ! ) = ;(;( b);(c) oi a) s+! h n 2 M N2 1F2 (a; b; c; ;x) (s + ! ) = ;(;( b);(c) i s + ! ;( a) s+!;1 h M 1 F2 (a; b; c; ;x) = ;(b);(c) 2 2 :
327
8.12. The Generalized Hardy{Titchmarsh Transform
Now we can apply (8.12.13) to obtain the relation
MJa;b;c;! (x) (s) = 2s+!;1
!
s
!
s
; 2 + 2 ; a; 2 ; 2 : ; b ; !2 ; 2s ; c ; !2 ; 2s
(8.12.16)
Multiplying the numerator and denominator in the right-hand side of (8.12.16) by ;(!=2 + s=2 + 1=2) and using the Legendre duplication formula (8.9.7), we obtain (8.12.10). We note that the rst two conditions in (8.12.4) with s being repalcing by (! + s)=2 yield conditions in (8.12.9) while the conditions b; c 6= 0; ;1; ;2; can be omitted by analytic continuation of both sides of (8.12.16) in b and c. Putting a = 1; b = + 1; c = + + 1 and ! = 2 + + 1=2 in (8.12.10) and taking into account (8.12.5), we arrive at (8.12.12) under the conditions in (8.12.11), which completes the proof of Lemma 8.19.
Remark 8.12. When = 0; (8.12.12) takes the form 1 + + s ; M[x1=2J (x)] (s) = 2; 1=2 3 2s 3 s : ; 4+2+2 ; 4+2;2
(8.12.17)
Applying the Legendre duplication formula (8.9.7) for ;(1=2 + + s); we have 1 + + s ; (8.12.18) M[x1=2J (x)] (s) = 2s;1=2 43 2 2s : ; 4+2;2 This formula is well known (see, for example, Prudnikov, Brychkov and Marichev [2, (2.12.2.2)]). Now we can apply the results in Chapters 3 and 4 to characterize the L;r -properties of the generalized Hardy{Titchmarsh transform (8.12.1) and the modi ed Hardy transform (8.12.6). If b 6= a and c 6= a; then according to (8.12.10) and (1.1.2), MJa;b;c;! (x) (s) is represented by the function H in the form 3 2 1 ! 1 ! 1 ; ; + ; 1 ; a + 7 6 2 2 2 2 2 1=2 1;1 6 s7 (8.12.19) MJa;b;c;! (x) (s) = H2;3 4 ! 1 5 ! 1 (!; 1); 1 ; b + 2 ; 2 ; 1 ; c + 2 ; 2 and hence, in accordance with (3.1.5), the transform Ja;b;c;! is a special H -transform:
Ja;b;c;! f
(x)
=
1 ! 1 ! 1 1; a+ 2; 2 ; 2 + 2; 2 ! 1 ! 1 ( 1); 1 ; b + ; ; 1 ; c + ;
Z 1 6 1=2 H21;;31 64xt 0 !; 2
2 2
2 2
3 7 7f 5
(t)dt:
(8.12.20)
328
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Similarly, by (8.12.12) and (1.1.2), M[x1=2J; (x)] (s) has the form
M[x1=2J; (x)] (s) 3 1 + + ; 1 ; 3 + + ; 1 7 4 2 2 4 2 2 7 1 + + 2; 1 ; 1 + ; 1 ; 1 ; ; 1 s5 ; 2 4 2 2 4 2 2
2
= 2;;2 1=2H21;;13 64 6
(8.12.21)
and the transform J; in (8.12.6) is an H -transform of the form:
J; f
(x) = 2;;2 1=2 1 1;1 6 H2;3 64xt 0 2
Z
3 1 + + ; 1 ; 3 + + ; 1 7 4 2 2 4 2 2 7 1 + + 2; 1 ; 1 + ; 1 ; 1 ; ; 1 5 f (t)dt: (8.12.22) 2 4 2 2 4 2 2
In particular, when = 0, 3 3 + ; 1 7 4 2 2 7 1 + ; 1 ; 1 ; ; 1 s5 ; 2 4 2 2
2
M[x1=2J (x)] (s) = 2; 1=2H11;;02 64 6
and hence we have the new representation for the Hankel transform 3 2 1 3 Z 1 + ; 7 6 H f (x) = 2; 1=2 H11;;20 64xt 14 2 2 1 1 75 f (t)dt: 0 2 + ; 1 ; 4 ; 2 ; 2
(8.12.23)
(8.12.24)
According to (3.4.1), (3.4.2), (1.1.7), (1.1.8), (1.1.9), (1.1.10), (1.1.11) and (1.1.12) we have = ;Re(! ); = 2Re(a) ; Re(! ); a = 0; = = 1; (8.12.25) 1 1 = ! + a ; b ; c; a1 = ; a2 = ; 2 2 for the H -function in (8.12.19), 3 1 = ;Re( + 2 ) ; ; = ;Re( + 2 ) + ; a = 0; = = 1; 2 2 (8.12.26) 1 1 1 = ; ; a1 = ; a2 = ; 2 2 2 for the H -function in (8.12.21), and 1 = ;Re( ) ; ; = +1; a = 0; = = 1; 2 1 1 1 = ; ; a1 = ; a2 = ; 2 2 2
(8.12.27)
329
8.12. The Generalized Hardy{Titchmarsh Transform
for the H -function in (8.12.23). Let EH1 , EH2 and EH3 be the exceptional sets of the functions H in (8.12.19), (8.12.21) and (8.12.23), respectively (see De nition 3.4). Then is not in the sets EH1 , EH2 and EH3 ; if = 1 ; Re(s) satis es s 6= 2b ; ! + 2k; s 6= 2c ; ! + 2l (k; l 2 N0); s 6=
and
3 ; + 2k; s 6= 3 + + 2l (k; l 2 N ) 0 2 2 3 2
s 6= + + 2k (k 2 N0 );
(8.12.28) (8.12.29) (8.12.30)
respectively Applying Theorems 3.6 and 3.7, we obtain the following results for the generalized Hardy{ Titchmarsh transform Ja;b;c;! and the modi ed Hardy transform J; in the space L;2 .
Theorem 8.45. Let a; b; c; ! 2 C ; (b 6= a; c 6= a) and 2 R be such that Re(! ) + 1 ; 2Re(a) < < Re(! ) + 1;
= 1 + Re(! + a ; b ; c):
(8.12.31)
(i) There is a one-to-one transform Ja;b;c ! 2 [L; ; L ;; ] such that the relation 2
;
;
1
2
MJa;b;c;! f (s)
;(! + s); a ; !2 ; 2s = 1=2 1 ! s ! s ! s Mf (1 ; s) ; 2 + 2 + 2 ; b; 2 ; 2 ; c; 2 ; 2
(8.12.32)
holds for Re(s) = 1 ; and f 2 L;2 . If the conditions in (8:12:28) are ful lled; then the transform Ja;b;c;! maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then 1;
Z
Ja;b;c;! f
0
(x)g (x)dx =
1
Z
0
;
f (x) Ja;b;c;! g (x)dx:
(8.12.33)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then J ; f is given by 2
;
Ja;b;c;! f
+
d (+1)=h x (x) = 1=2hx1;(+1)=h dx 1 1;2 6 H3;4 64xt 0 2
Z
3 (;; h); 1 ; a + !2 ; 21 ; 21 + !2 ; 21 7 7 5 ! 1 ! 1 (!; 1); 1 ; b + 2 ; 2 ; 1 ; c + 2 ; 2 ; (; ; 1; h) f (t)dt (8.12.34)
for x > 0. When Re() < (1 ; )h ; 1; for x > 0 ;
Ja;b;c;! f
d (+1)=h x (x) = ; 1=2hx1;(+1)=h dx
330
Chapter 8. Bessel Type Integral Transforms on the Space L;r
! 1 1 ! 1 1 ; a + 2 ; 2 ; 2 + 2 ; 2 ; (;; h) ! 1 ! 1 (; ; 1; h); (!; 1); 1 ; b + ; ; 1 ; c + ;
Z 1 6 H32;;41 64xt 0 2
2 2
3 7 7 5
2 2 f (t)dt: (8.12.35) (iv) Ja;b;c;! is independent of in the sense that if and e satisfy (8:12:31) and if the transforms Ja;b;c;! and eJa;b;c;! are given in (8:12:32) on the respective spaces L;2 and Le ;2 ; T then Ja;b;c;! f = eJa;b;c;! f for f 2 L;2 Le ;2 . (v) If f 2 L;2 and > 1+Re(! + a ; b ; c); then Ja;b;c;!f is given in (8:12:1) and (8.12.20).
Theorem 8.46. Let ; 2 C and 2 R be such that
Re( ) > ;1; Re( + ) > ;1; (8.12.36) Re( + 2 ) ; 12 < < Re( + 2 ) + 23 ; = 21 : (i) There is a one-to-one transform J; 2 [L;2; L1;;2 ] such that the relation Mfx1=2J; f g (s) 3 s 1 ; + + 2 + s ; 4 ; 2 ; ; 2 Mf (1 ; s) (8.12.37) = 2;;2 1=2 3 2 ; 4 + 2 + + 2s ; 43 ; 2 ; 2s ; 43 + 2 ; 2s holds for Re(s) = 1 ; and f 2 L;2 . If the conditions in (8:12:29) are ful lled; then the transform J; maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then 1;
Z
0
J; f
(x)g (x)dx =
Z
1
0
;
f (x) J; g (x)dx:
(8.12.38)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then J; f is given by 2
;
J; f
+
d (+1)=h x (x) = 2;;2 1=2hx1;(+1)=h dx
When Re() < (1 ; )h ; 1; ;
J; f
3 (;; h) ; 41 + 2 + 2 ; 21 ; 43 + 2 + ; 21 7 7 1 + + ; 1 ; 1 + ; 1 ; 1 ; ; 1 ; (; ; 1; h) 5 2 4 2 2 4 2 2 f (t)dt (x > 0): (8.12.39)
1 1;2 6 H3;4 64xt 0 2
Z
d (+1)=h x (x) = ;2;;2 1=2hx1;(+1)=h dx
1 + + ; 1 ; 3 + + ; 1 ; (;; h) 4 2 2 2 4 2 2 (; ; 1; h); 12 + + ; 1 ; 41 + 2 ; 21 ; 41 ; 2 ; 21
Z 1 6 2;1 6 H3;4 4xt 0 2
f (t)dt (x > 0):
3 7 7 5
(8.12.40)
331
8.12. The Generalized Hardy{Titchmarsh Transform
(iv)
J; is independent of in transforms J; and eJ; are given in T J; f = eJ; f for f 2 L;2 Le ;2 .
the sense that if and e satisfy (8:12:36) and if the (8:12:37) on the respective spaces L;2 and Le ;2 ; then
(v) If f 2 L; and > 1=2; then J; f is given in (8:12:6) and (8.12.22). 2
From Theorem 8.46 we obtain the corresponding statement for the Hankel transform H considered in Section 8.1.
Theorem 8.47. Let 2
C
and 2
R
be such that Re( ) > ;1 and 1=2 5 <
Re( ) + 3=2. (i) There is a one-to-one transform H 2 [L;2; L1;;2] such that the relation 1 ; ++s MH f (s) = 2; 1=2 3 2s 3 s Mf (1 ; s) ; 4+2+2 ; 4+2;2 ; 14 + 2 + 2s (8.12.41) = 2s;1=2 3 s Mf (1 ; s) ; 4+2;2 holds for Re(s) = 1 ; and f 2 L;2 . If the conditions in (8:12:30) are ful lled; then the transform H maps L;2 onto L1;;2 . (ii) If f; g 2 L;2; then 1
Z
H f
0
(x)g (x)dx =
Z
1
0
f (x) H g (x)dx:
(8.12.42)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then H f is given by 2
H f
+
d (+1)=h x (x) = hx1;(+1)=h dx
(;
When Re() < (1 ; )h ; 1;
H f
3 ); 43 + 2 ; 21 7 7 f (t)dt 5 1 1 1 1 + 2 ; 2 ; 4 ; 2 ; 2 ; (; ; 1; h) (x > 0): (8.12.43)
1 1;1 6 ; h H2;3 64xt 0 2
Z
d (+1)=h x (x) = ;hx1;(+1)=h dx
3 3 + ; 1 ; (;; h) 7 4 2 2 7 1 1 1 5 f (t)dt 1 (; ; 1; h); + 2 ; 2 ; 4 ; 2 ; 2 (x > 0): (8.12.44) (iv) H is independent of in the sense that if and e are such that 1=2 5 < Re()+3=2 and 1=2 5 e < Re( ) + 3=2; and if the transforms H and HeT are given in (8:12:41) on the respective spaces L;2 and Le ;2; then H f = He f for f 2 L;2 Le ;2. Z 1 6 H22;;30 64xt 0 2
332
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(v) If f 2 L; and > 1=2; then H f is given in (8:1:1) and (8.12.24). 2
Now we can apply Theorem 4.3 to obtain the boundedeness, range and representation of the generalized Hardy{Titchmarsh transform (8.12.1), the modi ed Hardy transform (8.12.6) and the Hankel transform (8:1:1) in the space L;r . By (8.12.20), the rst one is characterized in the following:
Theorem 8.48. Let 1 < r < 1 and let a; b; c 2 C (Re(a) > 0; b 6= a; c 6= a); ! 2 C and
2 R be such that
Re(! ) + 1 ; 2Re(a) < < Re(! ) + 1; = 21 + Re(! + a ; b ; c) + (r); (8.12.45) where (r) is given in (3:3:9): (a) The transform Ja;b;c;! de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = [ ; 1=2 + Re(b + c ; a ; ! )];1 with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform Ja;b;c;! is one-to-one on L;r and there holds the equality (8:12:32) for f 2 L;r and Re(s) = 1 ; . (c) Let f 2 L;r and g 2 L;s with 1 < s < 1 and 1=r + 1=s = 1. If = 1=2 + Re(! + a ; b ; c) + max[ (r); (s)]; then the relation (8:12:33) holds. (d) Let = ;Im(!) ; a + b + c ; 1. If the conditions in (8:12:28) are satis ed; then Ja;b;c;! (L;r ) =
M!+a;b;c+1=2 H (L ;Re(!+a;b;c);1=2;r );
(8.12.46)
where H is the Hankel transform (8:12:1) and M is the operator in (3:3:11). When any condition in (8:12:28) is not satis ed; Ja;b;c;! (L;r ) is a subset of the right-hand side of (8:12:46): (e) If f 2 L;r ; 2 C and h 2 R+; then Ja;b;c;! f is given in (8:12:34) for Re() > (1 ; )h ; 1; while by (8:12:35) for Re() < (1 ; )h ; 1. If > 2 + Re(! + a ; b ; c); then Ja;b;c;! f is given in (8:12:1) and (8.12.20). The replacement a = 1; b = + 1; c = + + 1; ! = 2 + + 1=2 in Theorem 8.48 yields L;r -theory of the modi ed Hardy transform (8.12.6).
Theorem 8.49. Let 1 < r < 1 and let ; 2 C and 2 R be such that Re( ) > ;1; Re( + ) > ;1; (8.12.47) Re( + 2 ) ; 12 < < Re( + 2 ) + 23 ; = (r); where (r) is given in (3:3:9). (a) The transform J; de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = 1= with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform J; is one-to-one on L;r and there holds the equality (8:12:37) for f 2 L;r and Re(s) = 1 ; . (c) Let f 2 L;r and g 2 L;s with 1 < s < 1 and 1=r + 1=s = 1. If = max[ (r); (s)]; then the relation (8:12:38) holds.
333
8.12. The Generalized Hardy{Titchmarsh Transform
(d) If the conditions in (8:12:29) are satis ed; then J; (L;r ) = H Re(+2) (L;r ):
(8.12.48)
When any condition in (8:12:29) is not satis ed; J; (L;r ) is a subset of the right-hand side of (8:12:48): (e) If f 2 L;r ; 2 C and h 2 R+; then J; f is given in (8:12:39) for Re() > (1 ; )h ; 1; while by (8:12:40) for Re() < (1 ; )h ; 1. If > 5=2; then J; f is given in (8:12:6) and (8.12.22). From Theorem 8.49 we obtain the corresponding statement for the Hankel transform H .
Theorem 8.50. Let 1 < r < 1 and let 2 C and 2 R be such that Re() > ;1;
Re( ) ; 1=2 < < Re( ) + 3=2 and = (r). (a) The transform H de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ] for all s with r 5 s < 1 such that s0 = 1= with 1=s + 1=s0 = 1. (b) If 1 < r 5 2; then the transform H is one-to-one on L;r and there holds the equality (8:12:41) for f 2 L;r and Re(s) = 1 ; . (c) Let f 2 L;r and g 2 L;s with 1 < s < 1 and 1=r + 1=s = 1. If = max[ (r); (s)]; then the relation (8:12:42) holds. (d) If the conditions in (8:12:30) are satis ed; then H (L;r ) = H Re() (L;r ):
(8.12.49)
When any condition in (8:12:30) is not satis ed; H (L;r ) is a subset of the right-hand side of (8:12:49): (e) If f 2 L;r ; 2 C and h 2 R+ ; then H f is given in (8:12:43) for Re() > (1 ; )h ; 1; while by (8:12:44) for Re() < (1 ; )h ; 1. If > 5=2; then H f is given in (8:1:1) and (8.12.24).
Remark 8.13. It follows from Theorems 8.49, that the range J; (L;r ) of the modi ed Hardy transform (8.12.6) coincides with the range H Re(+2) (L;r ) of the Hankel transform, while these transforms have di erent representations: (8.12.6), (8.12.22) and (8.1.1), (8.12.24). Since a = 0 for the transforms Ja;b;c;! ; J; and H , we can apply the results from Sections 4.9 and 4.10 to obtain their inversions. The constants and are given in (8.12.25), (8.12.26) and (8.12.27), while the constants 0 and 0 in (4.9.6) and (4.9.7) take the forms 0 = Re(! ) + 1 ; 2 min[Re(b); Re(c)];
0 = Re(! ) + 2
(8.12.50)
5 2
(8.12.51)
for Ja;b;c;! , 1 2
0 = jRe( )j ; ;
for J; and, in particular,
0 = Re( + 2 ) +
1 2
0 = jRe( )j ; ;
0 = Re( ) +
5 2
(8.12.52)
334
Chapter 8. Bessel Type Integral Transforms on the Space L;r
for H . In the case of the transform Ja;b;c;! the inversion formulas (4.9.1) and (4.9.2) take the forms f (x) = ;1=2hx1;(+1)=h
3 ) ; !2 ; 21 ; a ; !2 ; 21 ; 21 7 7 5 1 1 ! 1 1 ; 2 ; 2 ; 2 ; c ; 2 ; 2 ; 2 ; (;!; 1); (; ; 1; h) ;Ja;b;c;! f (t)dt (x > 0); (8.12.53)
; h ; 1 2;2 6 H3;4 64xt ! 0 b 2
d (+1)=h x dx
Z
(;
d (+1)=h x dx 2 1 ! 1 1 ! ; ; ; h) Z 1 6 2 2 ; a ; 2 ; 2 ; 2 ; (; H33;;41 64xt 0 (; ; 1; h); b ; ! ; 1 ; 1 ; c ; ! ; 1 ; 1 ; (;!; 1)
f (x) = ; ;1=2hx1;(+1)=h
2
2 2 Ja;b;c;!; f (t)dt (x > 0): ;
2 2
2
3 7 7 5
(8.12.54)
For the modi ed Hardy transform J; the inversion relations are given by f (x) = 2+2 ;1=2hx1;(+1)=h
1 1 1 1 (;; h); ; 4 ; 2 ; ; 2 ; 4 ; 2 ; ; 2 1 ; ; 1 ; 1 + ; 1 ; ; 1 ; ; 2; 1 ; (; ; 1; h) 4 2 2 4 2 2 2
Z 1 6 H32;;42 64xt 0 2
d (+1)=h x dx
;
J; f
(t)dt (x > 0);
3 7 7 5
(8.12.55)
d (+1)=h x dx 2 1 1 1 1 ; ; ; ; Z 1 6 4 2 2 ; 4 ; 2 ; ; 2 ;(;; h) H33;;41 64xt 0 (; ; 1; h); 1 ; ; 1 ; 1 + ; 1 ; ; 1 ; ; 2; 1
f (x) = ;2+2 ;1=2hx1;(+1)=h
4
2 2
4 2 2 2 J; f (t)dt (x > 0): ;
3 7 7 5
(8.12.56)
In particular, from (8.12.55) and (8.12.56) we have the inversion formulas for the Hankel transform by putting = 0: d (+1)=h x dx 2 1 1 (;; h); ; ; ; Z 1 6 H21;;32 64xt 1 1 2 4 2 1 0 + ; ; ; ; ; 1 ; (; ; 1; h)
f (x) = 2 ;1=2hx1;(+1)=h
2
4 2
2
3 7 7 H f 5
(t)dt (8.12.57)
335
8.12. The Generalized Hardy{Titchmarsh Transform
(x > 0); d (+1)=h x dx 2 1 1 ; ; ; Z 1 6 2 4 2 ; (;; h) H22;;31 64xt 0 (; ; 1; h); + 1 ; 1 ; ; ; 1 ; 1
f (x) = ;2 ;1=2hx1;(+1)=h
2 4 2
2
3 7 7 H f 5
(t)dt (8.12.58)
(x > 0):
Thus, we obtain the inversion results from Sections 4.9 and 4.10 for the transforms Ja;b;c;! ; J; and H in the spaces L;r and L2 (R+ ).
Theorem 8.51. Let a; b; c; ! 2 C (b 6= a; c 6= a); 2 R; and let 2 C and h > 0. (a) Let = 1 + Re(! + a ; b ; c); 0 < Re(b + c ; a) < 2 min[Re(a); Re(b); Re(c)]:
(8.12.59) If f 2 L;2 ; then the relation (8:12:53) holds for Re() > h ; 1; while (8:12:54) for Re() < h ; 1. (b) Let 1 < r < 1 and 1 ;2 min[Re(a); Re(b); Re(c)] < ; Re(!) ; 1 < min 0; Re(a ; b ; c) + 2 ; (8.12.60) 1 = + Re(! + a ; b ; c) + (r); 2 where (r) is given in (3:3:9). If f 2 L;r ; then the relation (8:12:53) holds for Re() > h ; 1; while (8:12:54) for Re() < h ; 1. Proof. The results (a) and (b) follow from Theorems 4.11 and 4.13, respectively. Indeed, by (8.12.25) and (8.12.50) the conditions for in Theorems 4.11 and 4.13 for the transform Ja;b;c;! take the forms 1 + Re(! ) ; 2Re(a) < < 1 + Re(! ); Re(! ) + 1 ; 2 min[Re(b); Re(c)] < < Re(! ) + 2; (8.12.61) = 1 + Re(! + a ; b ; c); and 1 + Re(! ) ; 2Re(a) < < 1 + Re(! ); Re(! ) + 1 ; 2 min[Re(b); Re(c)] < (8.12.62) 3 < min Re(! ) + 2; Re(! + a ; b ; c) + ; 2 1 = + Re(! + a ; b ; c) + (r): 2 The existence of such a value in each case is guaranteed from the assumptions (8.12.59) and (8.12.60).
336
Chapter 8. Bessel Type Integral Transforms on the Space L;r
Similarly, in view of (8.12.26), the conditions of Theorems 4.11 and 4.13 for the transform J; can be given by ; 21 + Re( + 2) < < 23 + Re( + 2); (8.12.63) jRe()j ; 12 < < Re( + 2) + 25 ; = 21 ; and ; 12 + Re( + 2) < < 23 + Re( + 2); (8.12.64) 5 1 jRe()j ; 2 < < min Re( + 2) + 2 ; 1 ; = (r); which are certi ed by (8.12.65) and (8.12.66) below, respectively. Then by noting that L1=2;2 = L2 (R+ ), we have
Theorem 8.52. Let ; 2 C be such that Re() > ;1, Re( + ) > ;1; and let 2 C
and h > 0. (a) Let
jRe()j < 1;
0 < Re( + 2 ) < 1:
(8.12.65)
If f 2 L2 (R+ ); then the relation (8:12:55) holds for Re() > h=2 ; 1; while (8:12:56) for Re() < h=2 ; 1. (b) Let 1 < r < 1 and 3 1 (8.12.66) max [Re( + 2 ); jRe( )j] ; 2 < < min 1; Re( + 2 ) + 2 ; = (r); where (r) is given in (3:3:9): If f 2 L;r ; then the relation (8:12:55) holds for Re() > h ; 1; while (8:12:56) for Re() < h ; 1. Taking = 0 in Theorem 8.52 and using (8.12.8), we obtain the corresponding results for the Hankel transform H in the spaces L2(R+ ) and L;r .
Theorem 8.53. Let 2 C ; Re() > ;1; and let 2 C and h > 0. (a) Let jRe()j < 1. If f 2 L (R ); then the relation (8:12:57) holds for Re() > h=2 ; 1; 2
+
while (8:12:58) for Re() < h=2 ; 1. (b) Let 1 < r < 1 and (r) 5 < max[Re() + 3=2; 1]; where (r) is given in (3:3:9). If f 2 L;r ; then the relation (8:12:57) holds for Re() > h ; 1; while (8:12:58) for Re() < h ; 1.
Remark 8.14. The relations (8.12.57) and (8.12.58) are new inversion formulas for the
Hankel transform H compared with those in (8.1.33) and (8.1.34) proved in Section 8.1.
337
8.13. The Lommel{Maitland Transform
8.13. The Lommel{Maitland Transform We consider the integral transform
J ; f
(x) =
1
Z 0
(xt)f (t)dt (x > 0) (xt)1=2J;
(8.13.1)
with the generalized Bessel{Maitland function (2.9.26):
(z ) = J;
1
+2k +2 z (;1)k k=0 ;(1 + + k);(1 + + + k) 2 X
(8.13.2)
(0 < 5 1; ; 2 C ; Re( ) > ;1; Re( + ) > ;1) as the kernel. Since, when = 1; (8.13.2) is the Lommel function (8.12.6) and the transform (8.13.1) coincides with the modi ed Hardy transform (8.12.6) studied in the previous section, we shall treat here the Lommel{Maitland transform J ; only for 0 < < 1. When = 0;
J (z ) J; 0(z ) =
1
+2k z (;1)k k=0 k!;(1 + + k) 2 X
(8.13.3)
for Re( ) > ;1; and (8.13.1) takes the form
J f
(x)
J ;0f
(x) =
Z 0
1
(xt)1=2J (xt)f (t)dt (x > 0):
(8.13.4)
by
We also note that the Bessel{Maitland function J ; (z ) in (2.9.24) is expressed via (8.13.3)
J ; (z) =
1
(;z )k ;=2 J (2pz ): = z k=0 k!;(1 + + k) X
(8.13.5)
The following L;r -theory of the Lommel{Maitland transform (8.13.1) is based on the Mellin transform of the function (8.13.2).
Lemma 8.21. Let 0 < < 1 and ; 2 C . (a) If Re() > ;1; Re( + ) > ;1 and s 2 C satis es ; 12 < Re(s) + Re( + 2) < 23 ;
(8.13.6)
then
(x)] (s) = 2;;2 1=2 M[x1=2J; ; 12 + + 2 + s ; 43 ; 2 ; ; 2s : (8.13.7) 3 3 1 s s
s ; 4 + 2 ++ 2 ; 4 ; 2 ; 2 ; 1++; 4 + 2 + ; 2
338
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(b) Let Re() > ;1 and s 2 C satisfy Re(s) > ;Re() ; 1=2. Then
1 ; ++s : M[x1=2J (x)] (s) = 2; 1=2 3 s 2
s 1 ; 4 + 2 + 2 ; 1+; 4 + 2 ; 2
(8.13.8)
Proof. It is known (see Betancor [1]) that
(x)] (s) M[x1=2J;
; 14 + 2 + + 2s ; 43 ; 2 ; ; 2s : (8.13.9) = 2s;1=2 3 s 1
s ; 4 ; 2 ; 2 ; 1++; 4 ++ 2 ; 2 Then, (8.13.7) is deduced from (8.13.9) if we multiply both sides of (8.13.9) by ;(=2 + + 3=4 + s=2) and use the Legendre duplication formula (8.9.7). The equality (8.13.8) follows from (8.13.7) when = 0; which completes the proof of Lemma 8.20.
Now we can apply the results in Chapters 3 and 4 to characterize the L;r -properties of
(x)])(s) the Lommel{Maitland transform (8.13.1). In view of (8.13.7) and (1.1.2), (M[x1=2J; is a special case of the function H of the form
(x)] (s) = 2;;2 1=2 M[x1=2J; 3 2 + + 1; 1 ; + + 3; 1 7 6 1;1 6 2 4 2 2 4 2 s7 (8.13.10) H2;3 4 5 1 1 1
1 + 2 + 2 ; 1 ; 2 + 4 ; 2 ; 2 + + 4 ; ; ; 2 and hence, in accordance with (3.1.5), the transform J ; f in (8.13.1) is regarded as a special H-transform (3.1.1): J ; f (x) = 2;;2 1=2 3 2 + + 1; 1 ; + + 3; 1 Z 1 7 6 4 2 2 4 2 7 H21;;31 64xt 2 5 0 + 2 + 12 ; 1 ; 2 + 41 ; 21 ; 2 + + 41 ; ; ; 2 f (t)dt: (8.13.11) If = 0; then by (8.13.8), (1.1.2) and Property 2.2 of the H -function, we nd 3 2 + 3; 1 7 6 s7 (8.13.12) M[x1=2J (x)] (s) = 2; 1=2H11;;02 64 2 14 2 1 5
+ 2 ; 1 ; 2 + 4 ; ; 2 and J f (x) 3 2 + 3; 1 Z 1 7 6 7 f (t)dt: (8.13.13) = 2; 1=2 H11;;20 64xt 2 14 2 1 5
0 ; ; ; 1 ;
+ + 2 2 4 2
8.13. The Lommel{Maitland Transform
339
For the Lommel{Maitland transform J ; the parameters can be evaluated in view of their de nitions (3.4.1), (3.4.2), (1.1.7){(1.1.12), and we have = ;Re( + 2) ; 21 ; = 23 ; Re( + 2 ); a = 1 ;2 ; = 1 +2 ; (8.13.14) =2 ; = ( ; 1) + 2 + 41 ; 21 ; a1 = 21 ; a2 = ; 2 = 2 2 for the transform (8.13.11), and = ;Re() ; 12 ; = +1; a = 1 ;2 ; = 1 +2 ; (8.13.15) =2 1 1 1
; = ( ; 1) 2 + 4 ; 2 ; a1 = 2 ; a2 = ; 2 =2 2 for the transform (8.13.13). Let EH1 be the exceptional set of the H -function H21;;31(z ) in (8.13.11) (see De nition 3.4). According to (8.13.7), is not in the exceptional set EH1 ; if = 1 ; Re(s) with s 6= ; ; 2 ; 32 ; 2k (k 2 N0 ); s 6= 23 ; + 2m (m 2 N0); (8.13.16) 1 s 6= ; + 2 + 2 + 2 (1 + + + n) (n 2 N0): If = 0; then in accordance with (8.13.8) is not in the exceptional set EH2 of the H -function H11;;20(z) in (8.13.13), if = 1 ; Re(s) with 1 3 (8.13.17) s 6= ; ; 2 ; 2k (k 2 N0 ); s 6= ; + 2 + 2 (1 + + n) (n 2 N0): Applying Theorems 3.6 and 3.7, we obtain the following results for the Lommel{Maitland transforms (8.13.1) and (8.13.4) in the space L;2 .
Theorem 8.54. Let 2 C ( 6= 0); 2 C and 2 R be such that the conditions
Re( ) > ;1; Re( + ) > ;1 and
Re( + 2 ) ; 12 < < Re( + 2 ) + 23
(8.13.18)
are satis ed and let 0 < < 1. (i) There is a one-to-one transform J ; 2 [L;2; L1;;2 ] such that the relation 9 s 1 ; + 2 + 2 + s ; 4 ; 2 ; ; 2 MJ ; f (s) = 2;;2 1=2 3 s 9 s ; 4 ++ 2 + 2 ; 4 ; 2 ; 2 1 Mf (1 ; s) (8.13.19) ; 1 + + ; 41 + + 2 ; s 2 holds for Re(s) = 1 ; and f 2 L;2 . If the conditions in (8:13:16) are ful lled; then the transform J ; maps L;2 onto L1;;2 .
340
Chapter 8. Bessel Type Integral Transforms on the Space L;r
(ii) If f; g 2 L; ; then 2
Z 0
1 J
; f (x)g (x)dx =
1
Z
0
f (x)
J ; g
(x)dx:
(8.13.20)
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then J ; f is given by 2
J ; f
+
d x(+1)=h (x) = 2;;2 1=2hx1;(+1)=h dx
1 1 (;; h); 2 + + 4 ; 2 ; 1 2;1 6 H3;4 64xt 1 1 1 0 + 2 + 2 ; 1 ; 2 + 4 ; 2 ; 2
Z
3 + + 3; 1 7 4 2 7 f (t)dt 2 (x > 0): (8.13.21) 5
2 + + 41 ; ; ; 2 ; (; ; 1; h)
When Re() < (1 ; )h ; 1;
J ; f
d x(+1)=h (x) = ;2;;2 1=2hx1;(+1)=h dx
+ + 1; 1 ; + + 3; 1 ; 1 1;2 6 4 2 2 4 2 H3;4 64xt 2 1 0 (; ; 1; h); + 2 + 2 ; 1 ; 2
Z
(;; h) + 1 ; 1 ; + + 1 ; ; ; 75 f (t)dt (x > 0):(8.13.22) 2 4 2 2 4 2 (iv) J ; is independent of in the sense that; if and e satisfy the assumption and if the transforms J ; and eJ; are given on L;2 and Le ;2 respectively by (8:13:19); then T
J ; f = eJ; f for f 2 L;2 Le ;2 . (v) For f 2 L;2; J ; f is given in (8:13:1) and (8:13:11). 3
Theorem 8.55. Let 2 C and 2 R be such that Re() > ;1 and < Re() + 3=2 and let 0 < < 1. (i) There is a one-to-one transform J 2 [L;2; L1;;2 ] such that the relation 1 ; ++s Mf (1 ; s) (8.13.23) MJ f (s) = 2; 1=2 3 s 2 ; 4 + 2 + 2 ; 1 + ; 41 + 2 ; s 2 holds for Re(s) = 1 ; and f 2 L;2 . If the conditions in (8:13:17) are ful lled; then the transform J maps L;2 onto L1;;2 . (ii) If f 2 L;2 and g 2 L;2; then Z
Z 1 1 J f (x)g (x)dx = f (x) J g (x)dx:
0
0
(8.13.24)
341
8.13. The Lommel{Maitland Transform
(iii) Let f 2 L; ; 2 C and h 2 R . If Re() > (1 ; )h ; 1; then J f is given by 2
J f
+
d x(+1)=h (x) = 2; 1=2hx1;(+1)=h dx
3 3 1 (;; h); 2 + 4 ; 2 1 1;1 6 7 7 f (t)dt (8.13.25) H2;3 64xt 5 1
1 0 + 2 ; 1 ; 2 + 4 ; ; 2 ; (; ; 1; h) 2
Z
(x > 0):
When Re() < (1 ; )h ; 1;
J f
d x(+1)=h (x) = ;2; 1=2hx1;(+1)=h dx
3 + 3 ; 1 ; (;; h) 1 2;0 6 7 7 f (t)dt (8.13.26) H2;3 64xt 2 4 2 1 1 5 0 (; ; 1; h); + 2 ; 1 ; 2 + 4 ; ; 2 2
Z
(x > 0):
(iv)
is independent of in the sense that; if and e satisfy the assumption and if the
transforms J and eJ are given on L;2 and Le ;2 respectively by (8:13:22); then J f = eJ f for f 2 L;2 T Le ;2. (v) For f 2 L;2; J f is given in (8:13:4) and (8:13:13): J
Now we characterize the boundedeness, range and representation of the Lommel{Maitland transform (8.13.1) and (8.13.4) in the space L;r , for which since a > 0; a1 > 0; a2 < 0; we may refer to Theorems 4.5 and 4.9.
Theorem 8.56. Let 2 C ( 6= 0); 2 C and 2 R be such that the conditions Re( ) > ;1; Re( + ) > ;1 and (8:13:18) are satis ed and let 0 < < 1. (a) If 1 5 r 5 s 5 1; then the transform J ; de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ]. If 1 < r 5 2 or if 1 < r < 1 and the conditions in (8:13:16) are satis ed; then J ; is a one-to-one transform from L;r onto L1;;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (8:13:20) holds. (c) Let 1 < r < 1 and let !; ; 2 C be chosen as ! = (1 ; ) +2 + + 41 ; (8.13.27) Re( ) = 1 ;1 2 max r1 ; 1 ; r1 + 2 (1 ; ) ; 1 ; Re(2 + ) ; 21 ; Re( ) > ; 1; Re( ) < 1 ; : 0
If the conditions in (8:13:16) are satis ed; then J ; (L;r ) =
M1=2;!= H ;!; ;1 L( ;1)=2;+1=2+!= (L3=2;Re(!)= ;;r );
(8.13.28)
342
Chapter 8. Bessel Type Integral Transforms on the Space L;r
where Lk; and H k; are the generalized Laplace and generalized Hankel transforms de ned in (3:3:3) and (3:3:4). If any condition in (8:13:16) is not satis ed; then J ; (L;r ) is a subset of the right-hand side of (8:13:28):
Theorem 8.57. Let 2 C and 2 R be such that Re() > ;1 and < Re() + 3=2
and let 0 < < 1. (a) If 1 5 r 5 s 5 1; then the transform J de ned on L;2 can be extended to L;r as an element of [L;r ; L1;;s ]. If 1 < r 5 2 or if 1 < r < 1 and the conditions in (8:13:17) are satis ed; then J is a one-to-one transform from L;r onto L1;;s . (b) If 1 5 r 5 s 5 1; f 2 L;r and g 2 L;s with 1=s + 1=s0 = 1; then the relation (8:13:24) holds. (c) Let 1 < r < 1: Let !; ; 2 C be chosen as in Theorem 8:56. If the conditions in (8:13:17) with = 0 are satis ed; then 0
J (L;r ) =
M1=2;!= H ;!; ;1 L( ;1)=2;+1=2+!= (L3=2;Re(!)= ;;r ):
(8.13.29)
If any condition in (8:13:17) with = 0 is not satis ed; then J (L;r ) is a subset of the right-hand side of (8:13:29): Proof. By virtue of (8.13.14) and (8.3.15), the assertions (a) of Theorems 8.56 and 8.57 follow from Theorems 4.5(a) and Theorem 4.9(a), while (b) and (c) are deduced from Theorem 4.5(b) and Theorem 4.9(b), respectively.
Remark 8.15. The boundedness of the Lommel{Maitland transform J ; for real from
L;r into L1;;s was given by Betancor [4, Theorem 2(a)] under more restrictive conditions
than that of Theorem 8.56(a) with real (see Section 8.14).
8.14. Bibliographical Remarks and Additional Information on Chapter 8 For Section 8.1. The classical results in the theory of the Hankel transform H in (8.1.1) are well known (see, for example, the books by Titchmarsh [3, Chapter VIII], Sneddon [1, Chapter II], Ditkin and Prudnikov [1, Part I, Chapter 3]) and Zayed [1, Section 27]. We only note that Titchmarsh [3, Theorem 135] rst proved the inversion formula for the Hankel transform in the form 1 [f (x + 0) + f (x ; 0)] = Z 1 (xt)1=2J (xt)H f (t)dt; (8.14.1) 2 0 provided that > ;1=2 and f (x) belongs to L1(R+ ), and is a bounded variation near the point x. Kober [1] was probably the rst to consider the mapping properties of the Hankel type operators in the space Lr (R+ ) (see the remarks on Section 8.4 below). The results presented in Theorems 8.1{8.4 and Lemmas 8.1{8.2 are extensions of those proved by Rooney [3], [4] and Heywood and Rooney [4] from real to the complex case. In proving Theorems 8.1(b), 8.1(c,d), 8.2, 8.3 and 8.4 we followed the proofs of Heywood and Rooney [4, Theorem 2.1], Rooney [4, Theorems 2.1, 2.2], Rooney [3, Theorem 2], Rooney [4, Theorem 2.3] and Heywood and Rooney [4, Theorem 3.1]. From other results we note those by Rooney [8] who proved another inversion formula, in addition to (8.1.33) and (8.1.34), for the Hankel transform (8.1.1) in the form
f (x) =
lim H k; H f (x); k!1
(8.14.2)
8.14. Bibliographical Remarks and Additional Information on Chapter 8
where
343
1
2 t2k++3=2 exp ;k xt 2 g(t)dt (8.14.3) 0 and which is valid for f 2 L;r ; provided that either 1 5 r < 1, (r) 5 5 + 3=2 or r = 1, 1 < < + 3=2 (Rooney [8, Theorem 4.1]). In terms of the operator H k; he also gave necessary and sucient conditions for f to be in the space of functions H (L;r ) = ff : f = H g; g 2 L;r g (8.14.4) characterized by di erent statements in the cases when > ;1 and < ;1 ( 6= ;3; ;5; ) (Rooney [8, Theorem 5.1, 5.5, 6.1 and 6.3]). We also mention the paper by Heywood and Rooney [2] where conditions were given on pairs of non-negative functions U(x) and V (x) which are sucient for the validity of the so-called two-weighted estimate
H k; g
k+1
(x) = 2kk! x;(2k++3=2)
1
Z 0
jU(x)
H f
(x)jsdx
Z
1=s
5
1
Z 0
jV (x)f(x)jr dx
1=r
(8.14.5)
with 1 < r 5 s < 1 for the Hankel transform H . Heywood and Rooney [8] showed that the Hankel transform (8.1.1) in an appropriate space L;r satis es ordinary and integral Lipschitz conditions. Tricomi [1] proved the connection between the Hankel transform (8.1.1) and the Laplace transform (2.5.2) in the form 1 = 2 ; ; 1 = 2 Lt H f(t) (x) = x Lt f(t) x ; and in [2] he established some Abelian and Tauberian theorems for H . Relations between the Hankel transform H , the Laplace transform L and the Varma transform V k;m given in (8.1.1), (2.5.2) and (7.2.15) of tf(t) were obtained by Bhonsle [2], [3] and by R.K. Saxena [4], respectively. Soni [1] derived various expansions for the Hankel transform (8.1.1) of any order > 0 on L2 (R+ ) by applying the fractional integration operators to the known expressions for H 0 . Relations between the fractional integration operators (2.7.1), (2.7.2) and the Hankel transform (8.1.1) were obtained by Bora and R.K. Saxena [1], and Martic [1], [2] gave an alternative proof of these results. The Hankel transform H in various spaces of tested and generalized functions was studied by Lions [1], Zemanian [1]{[3], [5], [6], Fenyo [1], [2], Koh and Zemanian [1], Koh [1]{[4], Lee [1], [2], Braaksma and Schuitman [1], McBride [3], Pathak [10], Pathak and A.B. Pandey [1], Pathak and Sahoo [1], Koh and Li [1], [2], Pathak and Upadhyay [1], Malgonde and Chaudhary [1], Betancor, Linares and Mendez [2], [3], Betancor and Marrero [1], Betancor and Rodriguez-Mesa [3], [4], Betancor and Jerez Diaz [3], Vu Kim Tuan [3], Kanjin [1], et al. We also mention the papers by Bhonsle and Chaudhary [1] who investigated the Laplace{Hankel transform with the kernel e;xt (xt)1=2J (xt) in a certain space of generalized functions, and by Betancor, Linares and Mendez [1], where Paley{Wiener theorems for the Hankel transform H f were proved. See in this connection the books by Zemanian [6], Brychkov and Prudnikov [1, Section 6.2] and Zayed [1, Section 21.7.1].
For Section 8.2. The well-known classical results in the theory of the Fourier cosine and sine transforms Fc and Fs, de ned by (8.1.2) and (8.1.3), on the spaces L1 (R+ ) and L2 (R+ ) were rst presented by Titchmarsh [3]. The results of this section given in Theorems 8.5{8.8 and concerning the properties of Fc and Fs on the space L;r were not mentioned earlier. For Section 8.3. The even and odd Hilbert transforms (8.3.1) and (8.3.2) were rst studied by Hardy and Littlewood [1] and Babenko [1], who proved that H+ 2 [L;r ] for ;r < < r and H; 2 [L;r ] for 0 < < r, respectively. Rooney [1, Corollary 8.1.2] extended the latter result to 0 < < 2r and showed that H+ and H; are one-to-one from L;r onto L;r if 1 < r < 2 or 0 < < r. The statements of Theorem 8.9 except (8.3.6) were also given by Rooney [4, Theorem 3.1]. The results in Theorem 8.11 were obtained by Heywood and Rooney [3, Theorem 4.1]. Using a technique of the Mellin transform for some auxiliary operators, they obtained inversion relations (8.3.20) and (8.3.21) and the characterization of the ranges H + (L;r ) and H ; (L;r ).
Chapter 8. Bessel Type Integral Transforms on the Space L;r
344
Prooving Theorem 8.9, we followed Rooney [4, Theorem 3.1]. The inversion formulas (8.3.18) and (8.3.19) for the even and odd Hilbert transforms (8.3.1) and (8.3.2) are not mentioned earlier.
For Section 8.4. As noted above in the comments on Section 8.1, the extended Hankel transform
H ;l in (8.4.1) with real was rst considered in the space Lr (R+ ) by Kober [1]. He proved sucient conditions for the transform H ;l to be bounded from Lr (R+ ) into Lr (R+ ), provided that 1 < r 5 2 (1=r + 1=r0 = 1) and f(x) satisfy some additional conditions. Busbridge [1] obtained simpler conditions for such a result. Erdelyi and Kober [1] investigated the modi ed extended Hankel transform, obtained from (8.4.1) by replacing the kernel (xt)1=2J;l (xt) by J;l [2(xt)1=2]. They gave conditions for the boundedeness of this operator from Lr (R+ ) for 1 5 r 5 2 and ;1=r0 < l + Re()=2 < 1=r, proved a Parseval theorem and discussed connections between two such operators with di erent and l. Erdelyi [2] investigated connections between the extended Hankel transforms of di erent order. The results presented in Section 8.4 are extensions of those proved by Rooney [5] and Heywood and Rooney [6] from real to the complex case. In the proofs of Theorem 8.12(a) and Theorems 8.12(b), 8.13, 8.14 and 8.15 we follow that by Rooney [5, Theorem 1] and Heywood and Rooney [6, Theorem 2.1], [6, Lemma 3.3], [6, Theorem 4.1], [6, Theorem 5.1], [6, Theorem 5.2] and [6, Theorems 6.6 and 6.9], respectively. We also mention Ahuja [1], [2] who investigated the extended Hankel transform H ;l in McBride spaces of tested and generalized functions Fp; and F0p; (see (5.7.8) and McBride [2]), and Vu Kim Tuan [3] who studied H;l in a space of rapidly decreasing functions and in the spaces Lp and in nitely di erentiable functions with bounded support. 0
For Section 8.5. The results presented in this section were proved by Kilbas and Trujillo [1]. They generalize those considered by many authors in the particular cases of the Hankel type transform H ;;$;k; in (8.5.1). Information concerning the investigation of the Hankel{Schwartz transforms h;1 = H ;+1;;;1;1 and h;2 = H ;;;+1;1;1 in (8.6.1) and (8.6.2) as well of the Hankel{Cli ord transforms b;1 = H ;=2;;=2;2;2 and b;2 = H ;;=2;=2;2;2 in (8.6.3) and (8.6.4), are given below in the comments on Section 8.6. As for other types of such transforms, we rst note the investigations by Sneddon who studied the transform 1
Z
H [f(at); x]
0
tJ (xt)f(at)dt = a;2 H ;0;1;1;1=af (x)
(8.14.6)
with a > 0 and > ;1=2, provided that x1=2f(x) is a piecewise continuously and absolutely integrable function on R+ . In particular, he proved the inversion formula of the form (8.13.1): 1 [f(x + 0) + f(x ; 0)] = Z 1 tJ (xt)H [f(t); x]dt: (8.14.7) 2 0 His results were presented in his book Sneddon [4, Chapter 5], where one can nd many references. Using the results obtained, Sneddon gave in terms of the integral transform (8.14.6) the exact solutions of axisymmetric Dirichlet problems for a half-space, for a thick plate and for the biharmonic equation, and applied these representations to problems in symmetrical vibrations of a large membrane and of a thin elastic plate, and in the motion of a viscous uid under a surface load (Sneddon [4, Chapter 5.10]). He also applied his results to the solution of dual integral equations and mixed boundary value problems [2], [4, Chapter 5.11] and of generalized axisymmetric potentials (Sneddon [4, Chapter 5.12]). We note that the inversion formula (8.14.7) was rst obtained by Cooke [1] for special functions f and = ; 1=2, and Bradley [1] extended this result to > ;1. Rooney [1, Sections 8 and 9] and Kilbas and Trujillo [2] considered the Hankel type transform de ned for f 2 C0 by
H; f (x) = x1;
1
Z
0
J (xt)t f(t)dt =
H ;1;;;1;1f
(x) ( > ;1):
(8.14.8)
Rooney showed that H; can be extended on L;2 as a unitary transform of the space into itself, i.e.
8.14. Bibliographical Remarks and Additional Information on Chapter 8
H;;1 = H; , and that, if f 2 L2;2, its Mellin transform is given by ; + 1 + s ; 2 Mf (2 ; s) (Re(s) = ): MH; f (s) = 2s; ++1;s ;
345
(8.14.9)
2
Rooney also proved that H; belongs to [L2=r;r ; L2=r ;r ], provided that 1 5 r 5 2 and 1=2 5 5 + 1, and characterized the constancy of its range as H;+ (L2=r;r ) = H; (L2=r;r ); (8.14.10) provided that 1 < r < 2 and 1=2 5 5 min[+ 1; + + 1]. The former results were applied to study the product of two transforms (8.14.8) de ned by H ;; = H;+ H; . The representations 0
0
;1
=2 = I; =;22;(;+1)=2 I0+;2 ;(+;1)=2 ( > 0; > ;1)
H ;;
(8.14.11)
and
;1 ; =2 = I0+;2 I;;;2 =;(2+ ;+1)=2 ( < 0; + > ;1) (8.14.12) ;(+ ++1)=2 were obtained in terms of the Erdelyi{Kober type fractional integration operators (3.3.1) and (3.3.2) and inverses to them, and on the basis of these relations the results on the boundedness and the one-to-one nature of H;; in L;r were proved. Kilbas and Trujillo [2] generalized the boundedness results by Rooney and gave the representation for H; .
H ;;
Theorem 8.58. (Kilbas and Trujillo [2, Theorem 3.1]) Let 1 5 r 5 1 and let (r) be given by (a) If 1 < r < 1 and (r) 5 ; Re() + 1=2 < Re() + 3=2; then for all s = r such that s0 > [ ; Re() + 1=2]; and 1=s + 1=s0 = 1; the operator H; in (8:14:8) belongs to [L;r ; L ;;s ] and is a one-to-one transform from L;r onto L ;;s . If 1 < r 5 2 and f 2 L;r ; then the Mellin transform of H; f for Re(s) = ; + 2Re() is given by (8:14:9): (b) If 1 5 ; Re()+1=2 5 Re()+3=2; then H; 2 [L; ; L ;;1 ]. If 1 < ; Re()+1=2 < Re() + 3=2; then for all r (1 < r < 1) H; 2 [L; ; L ;;r ]. (c) If f 2 L;r and g 2 L ; ;s for 1 < r < 1; 1 < s < 1 such that 1=r + 1=s = 1 and max[ (r); (s)] 5 ; Re() + 1=2 < Re() + 3=2; then the relation (3:3:9):
1
2Re( )
2Re( )
1
1
2Re( )+
1
Z
holds.
0
2Re( )
2Re( )
1
f(x) H; g (x)dx =
Z
0
1
g(x) H1;; f (x)dx
(8.14.13)
(d) If f 2 L;r for 1 < r < 1; (r) 5 ; Re() + 1=2 < Re() + 3=2; then for almost all x > 0 the relation d x+1 Z 1 J (xt)t f(t) dt (8.14.14) H; f (x) = x;; dx +1 t 0 holds. They also gave, in addition to (8.14.14), another representation for H; f and characterized the range H; (L;r ) of the Hankel type transform (8.14.8) in L;r -space in terms of the elementary operators (3.3.11) and (3.3.12), the Erdelyi{Kober operator (8.1.21) and the Fourier cosine transform (8.1.2) by
H; (L;r ) = M ;2+1; I ;; +1=2;;1=2Fc (L ;r ); (8.14.15) provided that 1 < r < 1 and (r) 5 ; Re() + 1=2 < Re() + 3=2. The inversion theorem was
also proved.
Chapter 8. Bessel Type Integral Transforms on the Space L;r
346
Theorem 8.59. (Kilbas and Trujillo [2, Theorem 3.3]) Let 1 < r < 1 and (r) 5 ; Re() + 1=2 < Re() + 3=2 or r = 1 and 1 5 ; Re() + 1=2 5 Re() + 3=2; where (r) is given by (3:3:9): If we choose the integer m > ; Re() + 1=2 and if f 2 L;r ; then for almost all x > 0 the inversion relation d m x+m Z 1 J (xt)t H f (t) dt (8.14.16) f(x) = x1;; x1 dx +1 ; tm 0 holds. In particular; if 1 < r < 1 and (r) 5 ; Re() + 1=2 < min[1; Re() + 3=2]; then Z 1 d +1 H; f (t) dt : ; ; x J (8.14.17) f(x) = x +1 (xt)t dx t 0 Kilbas and Marichev studied the generalized Hankel transform
S; ; f (x) = x; =2
1
Z
0
t; =2+;1J2+ 2 (xt)=2 f(t)dt
H 2+ ;; =2;; =2+;1;2=;2= f
(x)
(8.14.18)
Re(2 + ) = ; 21 ; > 0 and established its inversion formula and connections with the Erdelyi{Kober type operators (3.3.1) and (3.3.2), and Marichev applied the results to solve dual and triple integral equations with the Bessel function J (x) in the kernels (see Samko, Kilbas and Marichev [1, Sections 18.1 and 38.1-38.2]). These investigations generalize those by Sneddon [2], who rst suggested such a method by using the operators (8.14.18) with = 2: S; f = S; ;2f to solve dual integral equations. We also mention that Kalla and R.K. Saxena [2] obtained the relations between the operator S; and the generalized fractional integration operators containing the Gauss hypergeometric function in the kernels. K. Soni and R.P. Soni [1] obtained the Tauberian theorems for the generalized Hankel transform 1
Z
0
(xt); J (xt)dF (t)
(8.14.19)
with = ; 1=2 and a probability measure F on [0; +1). Betancor [2], [3] studied the Hankel type transform de ned by Z 1 F 0; 1; 2 f (x) = x 0; 2 (xt)(1; 1)=2; 2 J 2 +2 k (xt)(2+k)=2 f(t)dt 0 =
H ; 0 ;2 2+(1; 1 )=2;(1; 1)=2; 2 ;2=(2+k);2=(2+k)f
(x)
(8.14.20)
with real 0 ; 1, 2 and k and = ( 1 ; 1)=(2+k) = ; 1=2. He proved the inversion formula for such a transform provided that f is of bounded variation in a neighborhood of the point x0 > 0 and belongs to L;1 with = (1;k ; 1)=2; 2, and Parseval's type relations for such a transform. Betancor in [10] and [11] investigated the transform (8.14.20) in some spaces of generalized functions and gave applications to solve a Cauchy problem involving the Bessel type operator B 0 ; 1 ; 2 = x 0 Dx 1 Dx 2 (D = d=dx) in [10] and to solve several di erential equations involving such a Bessel type operator in [11]. Marichev and Vu Kim Tuan [1], [2] studied the isomorphism and factorization properties of the operator r Z 1 J 2 xt f(t) dtt 0 in special spaces of functions (see Samko, Kilbas and Marichev [1, Theorem 36.11]). We also note that Okikiolu [1], [2] studied the boundedness of the operator of the form (8.5.1) H ;;+1=2;1=2;;1;1 from
8.14. Bibliographical Remarks and Additional Information on Chapter 8
347
Lr (R+ ), and Duran [1] proved the isomorphism of some subspaces of the space of in nitely di erentiable functions C 1 (R+ ) with respect to the Hankel type operator H ;;!;1;1 .
For Section 8.6. The results presented in this section were proved by Kilbas and Trujillo [3]. Concerning other results on the Hankel{Schwartz transforms h and h in (8.6.1) and (8.6.2) and the Hankel{Cli ord transforms b and b in (8.6.3) and (8.6.4), we rst indicate Heywood and Rooney [1, Lemma 3] who proved that the Hankel{Cli ord operator b ( > ;1) de ned on C can be extended to a bounded operator in [L;r ; L ; ;;s], provided that 1 < r 5 s < 1, max[1=r; 1 ; 1=s] 5 2 + ; 1=2 and < 1. They de ned the operator ;1
;1
;2
;2
;1
0
1
Rk;; f
(x) = x; b+ ;1 Tk b;1 f (x) (x > 0; k > 0; > 0; 2 R)
(8.14.21)
being the composition of two Hankel{Cli ord operators b+ ;1 and b;1 with the translation operator Tk such that (Tk f)(x) = f(x ; k2 =4) for x > k2=4 and f(x) = 0 for 0 5 x 5 k2 =4, and they showed it is bounded in L;r ; provided that 1 < r < 1, < 1 and 1 1 max (r) ; 2 + 2 ; r0 ; 5 5 23 + ; 2 ; (r);
where (r) is given by (3.3.9). Heywood and Rooney applied the latter statement to investigate the integral operators
Jk (; )f (x) = 2 k1; x;2(+ )
and
Rk (; )f
(x) = 2 k1; x2
1
Z
x
Z
x 0
t2+1 (x2 ; t2 )( ;1)=2J ;1 k(x2 ; t2)1=2 f(t)dt (8.14.22)
t1;2(+ )(t2 ; x2 )( ;1)=2J ;1 k(t2 ; x2)1=2 f(t)dt (8.14.23)
in L;r with k > 0 and > 0 and real , containing the Bessel function of the rst kind (2.6.2) in the kernels. They proved the following result.
Theorem 8.60. (Heywood and Rooney [1, Theorem 4]) Let 0 < < 1=2. Then (i) If 2=(1 + ) 5 r 5 2; then Jk (; ) 2 [L;r ] for 5 1 + 2( + ); and Rk (; ) 2 [L;r ] for 5 4p; ; 2( + ) ; 1; (ii) If 2 5 r 5 2(1 ; ); then Jk (; ) 2 [L;r ] for 5 4p; + 2( + ) ; 1; and Rk (; ) 2 [L;r ] for = 1 ; 2( + ). 1
1
Soni [3] proved the criterion of invertibility of a simpler modi ed operator of the form (8.14.22) k ; )=2
Z
x
(1
0
(x2 ; t2 )( ;1)=2J ;1 k(x2 ; t2)1=2 f(t)dt (x > 0)
(8.14.24)
in the space L2 (R+ ). This operator was considered by many authors (see Samko, Kilbas and Marichev [1, (37.41) and Section 39.1, To Section 37.2]). In Sections 37 and 39 of this book one may nd the results and bibliographical remarks concerning other types of convolution and non-convolution operators generalizing the fractional integral operators (2.7.1) and (2.7.2) and containing Bessel functions J (z) and I (z) in the kernels. We only indicate the paper by Soni [2], who considered the simplest non-convolution operators Z
x 0
J0 kt1=2(x2 ; t2 )1=2 f(t)dt;
Z
1 x
J0 kx1=2(t2 ; x2)1=2 f(t)dt (x > 0);
(8.14.25)
proved the boundedness of these operators from Lp (R+ ) to Lp (R+ ) when 1 5 p 5 2 and 1=p0 +1=p = 1, and obtained the inversion formulas for the rst operator in the cases 2=3 < p 5 2 and p = 1. 0
Chapter 8. Bessel Type Integral Transforms on the Space L;r
348
It should be noted that the operators (8.14.22) and (8.14.23), being generalizations of the Erdelyi{ Kober type operators (3.3.1) and (3.3.2), were introduced by Lowndes [1] and given his name, who de ned the generalized Hankel transform ; a;b;y
S
; ;
f (x)
= 2 x2; (x2 ; a2);
1
Z
y
t1; ;2 (t2 ; y2 ) J2+ (x2 ; a2)1=2(t2 ; y2 )1=2 f(t)dt (8.14.26)
and in [5] a new unsymmetrical generalized operator of fractional integration (see the relation (37.68) in Samko, Kilbas and Marichev [1]). Then he gave applications of the operators to solving dual and triple integral equations in [1] and boundary value problems involving Helmholtz type partial di erential equations in [2]{[5]. In this connection see Samko, Kilbas and Marichev [1; Sections 37.2, 37.3, 38.1 (Examples 38.2 and 38.5), 39.1, 40.2 (Lemmas 40.1{40.3) and 43.2, note 40.1]. We also indicate some other results. R.K. Saxena and Sethi [1] investigated relations between the Lowndes operators (8.14.22), (8.14.23) and the generalized fractional integration operators involving the Gaussian hypergeometric function, and Ahuja [3], [4] studied Lowndes operators in McBride spaces Fp; and F0p; (see McBride [2] and (5.7.8)). Malgonde and Raj.K. Saxena [1] extended the operators of the form (8.14.22) and (8.14.23), in which x2 and t2 are replaced by xm and tm with m > 0, to spaces of generalized functions. Gasper and Trebels [1] studied in L;r the operator H( ) = D; h;2 of the composition of the Riemann{Liouvillefractional derivative (2.7.4) and the Hankel{Schwartz operator (8.6.2). They proved the estimate 1 1 ( ) (8.14.27) kH f k+1=2+1=r ;r 5 c kf k+ +1=2+1=r;r r + r0 = 1 ; provided that 1 < r 5 2, 0 < < + 3=2 and f belongs to the space S0 (k) (k = [2] + 4) of functions continuous on [0; 1), rapidly decreasing and in nitely di erentiable away from the origin, and such that H( ) has compact support in [0; 1) for all 2 (;1=2; k]. We note that the Hankel{Schwartz transforms h;1 and h;2 and the Hankel{Cli ord transforms b;1 and b;2 were studied in di erent spaces of tested and generalized functions. The Hankel{Schwartz transform h;2 , introduced by Schwartz [1], and its conjugate transform h;1 were investigated by Lee [3], Dube and Pandey [1], Schuitman [1], Altenburg [1], Chaudhary [1], van Eijndhoven and de Graaf [1], Mendez [1], [2], Mendez and Sanchez Quintana [1], [2], Sanchez Quintana and Mendez [1], Betancor [1], [9], Betancor and Negrin [1], van Eijndhoven and van Berkel [1], Linares and Mendez [1] and others (see the papers above and the book by Brychkov and Prudnikov [1, Section 6.4]). The Hankel{Cli ord transforms b;1 and b;2 were considered by Betancor [5]{[7], Mendez and Socas Robayna [1]. Duran [2] proved the isomorphism of some spaces of functions with respect to the modi ed Hankel{Cli ord transform Z 1 1 ; = 2 J (xt)1=2 t=2f(t)dt H f (x) = 2 x 0 ; (8.14.28) = 12 H ;;=2;=2;2;1f (x) ( > ;1): Mahato and Mahato [1] proved some Abelian theorems for the distributional Hankel{Cli ord transform (8.6.8). We also mention Betancor and Rodriguez-Mesa [1] who proved necessary and sucient conditions for a measurable function f(x) on R+ to satisfy the relation 0
f(x) = Tlim !1
Z
T 0
0
t2+1 (xt); J (xt) b;2 f (t)dt
; 21 < < 21
(8.14.29)
for almost all x 2 R+ , and used this formula to obtain a new inversion formula for the Hankel{Cli ord transform b;2 in (8.6.9).
8.14. Bibliographical Remarks and Additional Information on Chapter 8
349
For Sections 8.7 and 8.8. The transform Y in (8.7.1) and the Struve transform H in (8.8.1) were rst considered by Titchmarsh [1], [3, xx8.1 and 8.5] as a pair of reciprocal transforms: g(x) =
1
Z
0
k(xt)f(t)dt; f(x) =
1
Z
0
h(xt)g(t)dt
(8.14.30)
with k(x) = x1=2Y (x); h(x) = x1=2H (x):
(8.14.31)
These transforms are given as a pair of transforms in Erdelyi, Magnus, Oberhettinger and Tricomi [4, Chapter IX and X], where it is also indicated that these transformations are the inverses of each other, provided that ;1=2 < < 1=2. It should be noted that Hardy [1] presented the similar reciprocal relations g(x) =
1
Z 0
Y (xt)tf(t)dt; f(x) =
1
Z 0
H (xt)tf(t)dt;
(8.14.32)
as a particular case of more general formulas given below in (8.14.52) and (8.14.53) with = 1=2. For real the results presented in Sections 8.7 and 8.8 were proved by Rooney [4] and Heywood and Rooney [4]. Theorems 8.26{8.36 and Lemmas 8.6{8.11 are extensions of those proved by Rooney [4] and Heywood and Rooney [4] from real to the complex case. In our proofs of Theorems 8.26, 8.27(a,b), 8.27(c), 8.27(d), 8.27(e), 8.28, 8.29, 8.30 and 8.31 we follow Rooney [4, Theorem 4.1], Rooney [4, Theorem 4.2], Heywood and Rooney [4, Theorem 2.2], Rooney [4, Theorem 4.3], Rooney [4, Theorem 4.4], Rooney [4, Theorem 6.2], Heywood and Rooney [4, Theorem 4.1], Heywood and Rooney [4, Theorem 4.2] and Heywood and Rooney [4, Theorem 5.3], respectively. Similarly we follow Rooney [4, Theorem 5.1], Rooney [4, Theorem 5.2], Heywood and Rooney [4, Theorem 2.3], Rooney [4, Theorem 5.3], Rooney [4, Theorem 5.4], Rooney [4, Theorem 6.1], Rooney [4, Theorem 6.3] and Heywood and Rooney [4, Theorem 6.1] while proving Theorems 8.32, Theorem 8.33(a,b), Theorem 8.33(c), 8.33(d), 8.33(e), 8.34, 8.35 and 8.36, respectively. We note that the inversion formula for the Struve transform H was obtained in Theorem 8.36 for 2 C such that > ;Re() ; 1=2. Heywood and Rooney [7] proved the inversion formulas for the Struve transform with real for 5 ; ; 1=2:
Theorem 8.61. (Heywood and Rooney [7, Theorems 2.1, 2.3 and 3.2]) Let 1 < r < 1; = (r); where (r) is given by (3:3:9); and f 2 L;r . Then for almost all x > 0 Z 1 dt +1=2 1=2 ; ( +1=2) d x (xt) Y (8.14.33) f(x) = x +1 (xt) H f (t) dx t 0 for max[;( + 1=2); + 3=2] < < 1; d x+1=2 f(x) = x;(+1=2) dx " +1 # Z 1 dt cot() 1=2 H f (t) (8.14.34) (xt) Y+1 (xt) ; ;( + 2) xt 2 t 0 for < min[1; ;( + 1=2); + 5=2]; and d x+1=2 Z 1 (xt)1=2Y (xt)(H f)(t) dt (8.14.35) f(x) = x;(+1=2) dx +1 t !0 for = ;( + 1=2) and + 3=2 < < 1; where the integral in (8:14:35) is given in (8.7.46). The L;r -theory of the transforms Y and H can be also constructed by using their representations as special cases of the H -transform (3.1.1). Such an approach was developed by Kilbas and Gromak [1]. In this way new representations and new inversion relations for Y - and H -transforms were
Chapter 8. Bessel Type Integral Transforms on the Space L;r
350
established. Rooney [8, Corollaries 5.3 and 5.4 and Theorem 6.2] gave the necessary and sucient conditions for f to be in the spaces of functions Y (L;r ) = ff
: f = Y g; g 2 L;r g ( 2 R)
(8.14.36)
H (L;r ) = ff
: f = H g; g 2 L;r g ( 2 R)
(8.14.37)
and in terms of the operator H k; de ned by (8.14.3). Rooney [7, Theorem 2] and Heywood and Rooney [7, Theorem 3.4] characterized the ranges Y (L;r ) and H (L;r ) in the exceptional cases when = ; + 1=2 and = ; ; 1=2, respectively. We also indicate the paper by Vu Kim Tuan [2] in which the range of the transform Y was studied in some spaces of functions. Okikiolu [1], [2] studied the modi ed Y; and H; transforms of the form
Y; f
(x) = x
and
H; f
(x) = x
1
Z 0
1
Z 0
(xt)1=2; Y;1=2(xt)f(t)dt
(8.14.38)
(xt)1=2; H;1=2 (xt)f(t)dt
(8.14.39)
in the space Lp (R+ ). He showed that the above operators can be represented as the compositions of the Erdelyi{Kober type operators (3.3.1) and (3.3.2) with the cosine- and sine-transforms (8.1.2) and (8.1.3). Love [4] studied the modi ed Struve transform de ned for 2 C (Re() > ;1=2) and x > 0 by
S f (x) =
Z 0
1
p
p
(x t) H (x t)f(t)dt
in the space L;1;1 and established the inversion relation of the form Z1 p sin(t x)t;2 S f (t)dt; I;+1=2 f (x) = p2 0
(8.14.40)
(8.14.41)
where I;+1=2 f is the fractional integral (2.7.2). McKellar, Box and Love [1] proved the inversion theorems for the modi ed Struve transform 1=2 Z 1 (xt)1=2;nHn+1=2 (xt)f(t)dt (n 2 N0 ): (8.14.42) 2 0 Isomorphism and factorization properties of the operators r
r
Z 1 dt x H 2 xt f(t) dtt (8.14.43) Y 2 t f(t) t ; 0 0 in special spaces of functions were investigated by Marichev and Vu Kim Tuan [1], [2] (see Samko, Kilbas and Marichev [1, Theorems 36.12 and 36.13]). Z
1
For Section 8.9. The transform K in (8.9.1) was introduced by Meijer [1] and therefore given his name. Meijer [1], [2] considered the reciprocal formulas 1=2 Z 1 (xt)1=2K (xt)f(t)dt; g(x) = 2 0
(8.14.44)
1=2 Z +i1 1 (xt)1=2I (xt)g(t)dt; f(x) = i 2
;i1
(8.14.45)
8.14. Bibliographical Remarks and Additional Information on Chapter 8
351
where I (z) is the modi ed Bessel function of theZ rst kind (8.9.3). Meijer [1], [2] proved that if f(t) 1 is a bounded variation function and the integral e; t jg(t)jdt is convergent, then (8.14.44) implies 0 (8.14.45) provided that ;1=2 5 5 1=2. Such a result is also true for 2 C , Re() = ; 1=2 (see Zayed [1, Section 23.5]). When = ;1=2, the right side of (8.14.44) coincides with the Laplace transform (2.5.2) (see (8.9.4)), while the right side of (8.14.45) coincides with the complex inversion formula for the Laplace transform (see, for example, Titchmarsh [3, Sections 1.4 and 11.7]). Boas [1] gave an inversion formula for the transform 1=2 Z 1 (xt)1=2K (xt)d (t); (8.14.46) g(x) = 2 0 which generalizes the Post{Widder inversion operator for the Laplace transform (see Widder [1]). Using the Erdelyi{Kober fractional integration operators (3.3.1) and (3.3.2), Fox [3] reduced the modi ed Meijer transform
K; f
(x) =
1
Z
0
(xt) K (xt)f(t)dt (x > 0)
(8.14.47)
to the form of a Laplace transform and obtained its inversion formula. In [4] he gave such a solution as an illustration of a method, developed by him and based on direct and inverse Laplace transforms, to nd a formal solution of the rst equation in (8.14.30) with the kernel k(x) such that its Mellin transform (2.5.1) has the form (Mk)(s) =
n Y i=1
2
;(ai + i s) 4
m Y j =1
3;1
;(bj + j s)5 :
(8.14.48)
Gonzalez de Galindo and Kalla [1] used this method to nd the inversion for the modi ed Meijer transform 1
Z
0
ext K (xt)f(t)dt:
(8.14.49)
It should be noted that earlier Conolly [1] on the basis of the direct and inverse Laplace transforms suggested a formal process to obtain the inversion formula for the modi ed Meijer transform
K; ;! f
(x) = x!
Z
0
1
(xt) ;1=2K;1=2 (xt)f(t)dt
(8.14.50)
with ! = 0 and = 1=2. Such a modi ed Meijer transform in the space Lp (R+ ) was studied by Saksena [1] for p = 2, ! = 0 and = > 1=2, Okikiolu [1], [2] and Manandhar [1] for p = 1 and 2 R. They applied the Erdelyi{Kober type fractional integrals (3.3.1) and (3.3.2) and the Mellin transform to nd the inversion relations for such a modi ed Meijer transform. Okikiolu [1], [2] showed that the operator K; ;! can be represented as a composition of the generalized Laplace transform and Erdelyi{Kober type operator (3.3.2), and that K; ;! is bounded from Lp (R+ ) into Lq (R+ ), where 1=q = 1 ; ! ; 1=p > 0. K.C. Sharma [1] investigated the compositions of the modi ed Meijer transforms K+1=2;1;1 in (8.14.50) with di erent indices , and in [2] he gave four inversion formulas for such a transform in terms of direct and inverse Mellin transforms and by means of the inversion formulas for Mellin and Y-transforms, Mellin and Hankel transforms and a formal process suggested by Conolly [1]. Nasim [1] obtained the inversion formula for the transform K+1=2; +1=2;0 with jj 5 1=2 and > 0 in terms of the Hankel transform (8.1.1) by using an in nite-order di erential operator. Bora and R.K. Saxena [1] showed that the Meijer K -transform (8.9.1) can be represented as the f(x2 ) and x2;2I f(x;2 ), where I and I are the Laplace transform (2.5.2) of the functions I0+ ; ; 0+ fractional integration operators given in (2.7.1) and (2.7.2). Martic [1], [2] gave an alternative proof of these results. Connections of the Meijer transform (8.9.1) with the Laplace transform (2.5.2) and
Chapter 8. Bessel Type Integral Transforms on the Space L;r
352
the generalized Varma transform (7.3.1) were studied by Bhonsle [1] and Bhise [2], with the Varma transform (7.2.15) by Bhise [2] and Gupta [1], and with the Hankel transform (8.1.1) by Bhise [2]. Zemanian [3], [4], Fenyo [1], [2], Koh and Zemanian [1], Koh [1], Barrios and Betancor [4], [5], Betancor and Barrios [1], Malgonde [2], Mahato and Agrawal [1], and Betancor and Rodriguez-Mesa [2] studied the Meijer transform K in some spaces of tested and generalized functions (see in this connection the books by Zemanian [5], Brychkov and Prudnikov [1, Section 6.7]) and Zayed [1, Section 23.7]. Conlan and Koh [1], Koh, Deeba and Ali [1], [2], Deeba and Koh [1] investigated the Meijer type transform
K f (x) =
1
Z
0
(xt)=2 K (xt)1=2 f(t)dt
(8.14.51)
in some spaces of generalized functions and gave applications to construct an operational calculus for the Bessel operator B = t; Dt1+ D (D = d=dt), and to solve a boundary value problem for the one-dimensional wave equation. The results presented in Section 8.9 were obtained by Kilbas, Saigo and Trujillo [1].
For Section 8.10. The Bessel type transforms K and Lm in (8.10.1) and (8.10.2) were introduced by Kratzel in [5] and [1], respectively. For the transform K an inversion and convolution theorem were given by Kratzel [5], and an operational calculus was constructed by Rodriguez, Trujillo and Rivero [1]. Compositions of K with the Riemann{Liouville fractional integration (2.7.1), (2.7.2) (
)
and fractional di erentiation operators (2.7.3), (2.7.4) in certain weighted spaces of locally integrable and nite di erentiable functions were proved by Kilbas and Shlapakov [1], [3] with applications to the solution of ordinary linear di erential equations of the second kind. Such compositions in McBride spaces of tested and generalized functions Fp; and F0p; (McBride [2]) were given by Kilbas, Bonilla, Rodriguez, Trujillo and Rivero [1]. The properties of L(m) such as an inversion and convolution theorem, operational rules, di erentiation relations, and connections with di erential operators were investigated by Kratzel [1]{[4]. Barrios and Betancor [1] obtained two real inversion formulas and discuss Abelian and Tauberian theorems for the transform L(m) . Rao and Debnath [1], Barrios and Betancor [2], [3], and Malgonde [2] investigated this transform in some spaces of generalized functions. The results presented in Section 8.10 were proved by Kilbas and Glaeske [1] and Glaeske and Kilbas [1]. in (8.11.1) was introduced by KilFor Section 8.11. The modi ed Bessel type transform L; ( )
bas, Saigo and Glaeske [1] and Glaeske, Kilbas and Saigo [1] and they proved its Mellin transform ) with (8.11.11), the asymptotic relations (8.11.20) and (8.11.21) and the composition formulas of L(; the left- and right-sided Liouville fractional integrals and derivatives on McBride spaces Fp; and F0p; . The results presented in Section 8.11 were proved by Bonilla, Kilbas, Rivero, Rodriguez and Trujillo [1].
For Section 8.12. The transform of the form (8.12.6) with (xt) = J; (xt) being replaced by J; (xt) 1 2
is known as the Hardy transform. Hardy [1] established a pair of reciprocal relations (8.14.30) of the form g(x) =
Z
0
1
C; (xt)tf(t)dt; C; (z) = cos()J (z) + sin()Y (z)
and f(x) =
1
Z 0
J; (xt)tg(t)dt;
(8.14.52) (8.14.53)
where J; (z) is given by (8.12.4). Because of this both transforms in (8.14.52) and (8.14.53) are called Hardy transforms. Cooke [1] obtained the following inversion formula for the transforms (8.14.52) and (8.14.53).
8.14. Bibliographical Remarks and Additional Information on Chapter 8
353
Theorem 8.62. (Cooke [1]) Let > ;1; + > ;1 and let f(t) be a function of bounded variation in the neighborhood of the point t = x.p (i) If j + 2j < 3=2; tf(t) 2 L(0; ) and tf(t) 2 L(; 1); where > 0 and = min[1 ; jj; (1 ; ; )=2]; then 1 [f(x + 0) + f(x ; 0)] = Z 1 J (xt)tdt Z 1 C (t ) f( )d : (8.14.54) ; ; 2 0 0 p (ii) If + 2 < 3=2; jj 5 3=2; tf(t) 2 L(0; ) and tf(t) 2 L(; 1); where > 0 and = min[1 + + 2; 1=2]; then 1 [f(x + 0) + f(x ; 0)] = Z 1 C (xt)tdt Z 1 J (t ) f( )d : (8.14.55) ; ; 2 0 0 Srivastava [3] proved certain theorems for the Hardy transform (8.14.53). Connections of this transform with the Varma transform (7.2.15) were investigated by Srivastava [4], withZthe generalized 1 Varma transform (7.3.1) by Srivastava [3], and with the integral operator (Kf)(x) = x k(xt)f(t)dt 0 of the general form by Kalla [9]. Moiseev, Prudnikov and Skurnik [1] considered the particular case of the transform (8.12.1) with a = 1; b = + 1; c = + 3=2 and ! = 2 + 1 in the form Z 1 2 2 +1 3 (xt) (xt) (8.14.56) F (x) = ;(2 + 2) 1F2 1; + 1; + 2 ; ; 4 f(t)dt 0 in the space Lr (R+ ). They proved [1, Theorem 1] that this transform is one-to-one in Lr (R+ ) for a 2 [;1=2; 1=2); and established its inversion formula Z 1 2 sin(xt ; )F (t)dt; (8.14.57) f(x) = 0 provided that a 2 [;1=2; 1=4). Pathak and J.N. Pandey in [1], [3] extended the Hardy transform (8.14.52) to special spaces of generalized functions and, in particular, obtained the inversion formula for such a distributional Hardy transform (see some of their results in Zayed [1, Section 22.6]). In [2] Pathak and J.N. Pandey proved four Abelian theorems for the Hardy transforms (8.14.52) and (8.14.53). The generalized Hardy{Titchmarsh transform (8.12.1) with ! = b + c ; a ; 1=2
Ja;b;cf (x) =
where Ja;b;c(x) =
Z
0
1
Ja;b;c(xt)f(t)dt;
(8.14.58)
1 X
(;1)k ;(a + k) x 2k+b+c;a;1=2 k=0 ;(b + k);(c + k)k! 2
x b+c;a;1=2 2 x ;(a) (8.14.59) = ;(b);(c) 2 1 F2 a; b; c; ; 4 was studied by Titchmarsh [3, Section 8.4, Example 3]. Considering (8.14.58) as the rst reciprocal transform in (8.14.30) with the kernel k(x) = Ja;b;c(x), Titchmarsh proved the inversion formula in the form of the second reciprocal transform in (8.14.30) with ; b) x a+b;c;1=2 F 1 ; a + b; 1 + b ; c; b; ; x2 h(x) = sin(a 1 2 sin(c ; b) 2 4 x a;b+c;1=2 2 x sin(a ; c) (8.14.60) + sin(b ; c) 2 1 F2 1 ; a + c; 1 ; b + c; c; ; 4 :
Chapter 8. Bessel Type Integral Transforms on the Space L;r
354
Titchmarsh noted that these reciprocal transforms can also be obtained from the results by Fox [1]. The particular case a = + 3=2, b = + 1 and c = 2 + 1 with p d h x i p (8.14.61) k(x) = 2 dx xJ2 2 ; h(x) = ; J x2 Y x2 was investigated earlier by Bateman [1], [2]. The case a = ++1=2, b = ++1, c = 2++1 yields a more general transform considered by Titchmarsh [2]; the inversion relation for such a transform was proved by Cook [1]. Bhise and Dighe [1] proved Tauberian theorems for the transform of the form (8.14.58), while Dighe and Bhise [1] established Abelian theorems for such a transform. H.M. Srivastava [1] introduced the transform more general than (8.14.58): 2 2 Z 1 ; (8.14.62) J f (x) = t ;; x 4t f(t)dt 0 with the kernel 1 x k+=2 p X (;1)k ( + k + 1)k (8.14.63) ;; (z) = k=0 ;( + k + 1);( + k + 1)k! 4 and investigated the relations of this transform with the Laplace transform (2.5.2) and the Meijer transform (8.9.1) in [1] and [2], respectively. Srivastava and Vyas [1] obtained a relationship between the J; -transform and the generalized Whittaker transform (7.3.1). The results presented in Section 8.12 were obtained in Kilbas, Saigo and Borovco [2], [3]. Some of these assertions in the particular case ! = b+c ; a ; 1=2 for real were given by Kilbas and Borovco [1].
For Section 8.13. The Lommel{Maitland transform J ; in (8.13.1) was rst considered by Pathak [1]{[3], who obtained some elementary properties of this transform, proved the inversion formula and
indicated the relation of this transform with the Laplace transform and applied the results obtained to evaluate a number of in nite integrals involving Meijer's G-function. The Lommel{Maitland transform J ; with real in the spaces L;r with 1 < r < 1, 2 R, max[1=r; 1=r0] 5 < 1 and r 5 s < 1=(1 ; ) was considered by Betancor [4]. He proved the boundedness of J ; from L;r into L1;;s provided that 0 < < 1 and the conditions 9 (8.14.64) > ;1; + > ;1; 1 + max 1; + 2 ; 2 < < + 2 + 23 : These conditions are harder than that of Theorem 8.56(a) for real . Betancor also gave conditions for characterizing the range of the Lommel{Maitland transform (8.13.1) in terms of the Fourier cosine transform (8.1.2) by J ; (L;r ) Fc (L;r ) and J ; (L;r ) = Fc (L;r ), and for the imbedding J 11 ;1 (L;r ) J 22 ;2 (L;r ) with di erent i ; i and i (i = 1; 2). The results presented in Section 8.13 were obtained by the authors together with Borovco in Kilbas, Saigo and Borovco [1]. The particular case of the Lommel{Maitland transform J in (8.13.4) in the form Z
1
x2t2 f(t)dt (x > 0); (8.14.65) (x) = 4 0 where J ; (z) is the Bessel{Maitland function (8.13.5), was considered by Agarwal [1]{[3], who gave the Parseval relation and some other properties of this transform proving three inversion formulas: in a form similar to (8.13.4), in terms of a double integral and as a di erential operator of in nite order. Betancor [12] obtained another inversion formula and proved Abelian theorems for the transform (8.14.65). We mention several results concerning integral transforms with the Bessel{Maitland function (8.13.5) in the kernel. Marichev [1] studied the transform
J ; f
J ; f
(x) =
(xt)+1=2 J ;
Z
0
1
(xt)1=2J ; (xt)f(t)dt (x > 0)
(8.14.66)
8.14. Bibliographical Remarks and Additional Information on Chapter 8
355
in L2 (R+ ). Kumar [1]{[4] studied properties of the modi ed transform
J ; f (x) =
1
Z
0
(xt) J ; (xt)f(t)dt (x > 0)
(8.14.67)
including the existence, recurrence relations, and connections with Laplace and Hankel transforms and gave applications to evaluate some integrals. R. Gupta and Jain [1], [2] investigated such a modi ed transform in some spaces of generalized functions. Betancor [8] proved the boundedness and the range in L;r of the so-called Watson{Wright transform de ned by
0
1
Z
; H ; ; ; f (x) = 0
;
; x2 t2 f(t)dt (x > 0) (xt) w; ; 0
0
0
(8.14.68)
with > ;1; 0 > ;1, and 0 < < 1 or = 1; 0 ; > ;1=2, and 0 < 0 < 1 or 0 = 1; + > ;1=2. Such a transform, introduced by Olkha and Rathie [1], [2], contains the function Z 1
; (x) = x1=2 ;1J ; (xt)J ; 1 dt (8.14.69) w; t ; t 0 in the kernel, which for = 0 = 1 and = 0 coincides with the function Z 1 > ; 21 ; 0 > ; 21 (8.14.70) w; (x) = x1=2 J (xt)J 1t dtt 0 de ned by Watson [1]. Bhatnagar [1], [2] studied the functions of this type as the kernels k(x) and h(x) of a pair of reciprocal transforms (8.14.30). Using the Kober operators (7.12.5) and (7.12.6), K.J. Srivastava [2], [3] investigated the integral transform 0
0
0
0
0
0
W ; f 0
(x) =
Z
1
w; (xt)f(t)dt 0
0
with such a function kernel in the space L2(R+ ).
(8.14.71)
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AUTHOR INDEX Buschman R.G., ix, xii, 36, 67, 131, 161, 163, 259, 359, 360, 373
Agarwal R.P., 354, 357 Agrawal B.M., 67, 357 Agrawal N.K., 352, 366 Ahuja G., 344, 348, 357 Ali M.A., 352, 365 Altenburg G., 348, 357 Anandani P., 67, 68, 357 Arya S.C., 252, 255, 259, 357
Carmichael R.D., 92, 254, 360 Chaudhary M.S., 164, 343, 348, 359, 360, 367 Chaurasia V.B.L., 67, 360 Conlan J., 352, 360 Conolly B.W., 351, 360 Cooke R.G., 344, 352{354, 360
Babenko K.I., 343, 357 Bajpai S.D., 67, 68, 357 Banerjee D.P., 254, 357 Barrios J.A., 352, 357, 358 Bateman H., 354, 358 van Berkel C.A.M., 348, 360 Betancor J.J., xii, 92, 127, 338, 342, 343, 346, 348, 352, 354, 355, 357, 358 Bhatnagar K.P., 355, 358 Bhise V.M., 127, 161, 199, 201, 352, 354, 359, 360 Bhonsle B.R., 343, 352, 359 Boas R.P., Jr., 351, 359 Bochner S., 27, 359 Boersma J., 68, 359 Bonilla B., xi, 70, 352, 359, 364 Bora S.L., 67, 254, 343, 351, 359 Borovco A.N., xii, 354, 364 Box M.A., 350, 368 Braaksma B.L.J., x, 10, 12{15, 18, 21, 26{30, 67, 258, 343, 359 Bradley F.W., 344, 359 Brychkov Yu.A., x, xii, 5, 26, 47, 48, 56, 61, 62, 67{69, 92, 199, 207, 208, 213, 216, 219, 223, 227, 241, 251, 253, 255, 256, 260, 267, 273, 307, 326, 327, 343, 348, 352, 359, 370 Busbridge W., 344, 359
Dange S., 164, 360 de Amin L.H., 163, 360 Debnath L., xii, 352, 360, 370 Deeba E.Y., 352, 360, 365 Dighe M., 127, 161, 354, 359, 360 Ditkin V.A., x, 43, 48, 68, 251, 342, 360 Dixon A.L., 25, 360 Doetsch G., 43, 251, 360 Dube L.S., 348, 360 Duran A.J., 347, 348, 360 van Eijndhoven S.J.L., 348, 360 Erdelyi A., 3, 25, 32, 35, 41, 42, 48, 62{66, 69, 82, 92, 108, 207, 216, 219, 252, 254{ 257, 259, 263, 264, 266, 270, 289, 292, 293, 295, 298, 303, 307, 311{314, 325, 344, 349, 360, 361 Fenyo I., 343, 352, 361 Ferrar W.L., 25, 360 Fox C., 26, 27, 68, 90, 126, 128, 129, 131, 198, 199, 253, 351, 354, 361 Galue L., 161, 361 Gasper G., 348, 361 Gaur N., 260, 361 381
382
Glaeske H.-J., x{xii, 70, 127, 199, 258, 260, 323, 352, 359, 361, 364, 370 Golas P.C., 200, 260, 361 Gonzalez de Galindo S.E., 351, 361 Goyal A.N., 67, 361 Goyal G.K., 61, 67, 69, 361 Goyal R.P., 200, 254, 361 Goyal S.P., x, xii, 19, 26, 30, 36, 39, 47, 56, 61, 67{69, 161, 200, 253, 254, 260, 361, 371, 373 de Graaf J., 348, 360 Grin'ko A.P., 259, 362 Gromak E.V., 349, 364 Gupta K.C., x, xii, 19, 26, 30, 36, 39, 47, 56, 61, 67{69, 90, 129, 130, 161, 163, 201, 253, 254, 256, 352, 362, 372, 373 Gupta N., 201, 372 Gupta R., 355, 362 Habibullah G.M., 253, 254, 256, 362 Haidey V.O., 164, 374 Halmos P.R., 84, 362 Hardy G.H., 343, 349, 352, 362 Heywood P., 259, 276, 280, 297, 298, 306, 342{344, 347, 349, 350, 362 Higgins T.P., 257, 259, 362 Jain R.M., 254, 260, 361, 373 Jain R.N., 68, 363 Jain U.C., 26, 61, 67{69, 254, 355, 362, 363 Jerez Diaz C., xii, 92, 127, 343, 358 Joshi J.M.C., 131, 255, 260, 363 Joshi N., 131, 363 Joshi V.G., 92, 363 Kalla S.L., 67, 127, 129, 161{163, 202, 253, 256, 257, 346, 351, 353, 359{361, 363, 369 Kanjin Y., 343, 363 Kapoor V.K., 198, 200, 201, 363, 367 Karlsson P.W., 260, 373 Kashyap N.K., 256, 366, 370 Kesarwani R.N., 91, 126, 128, 129, 197{200, 253, 364, 375
Author Index
Kilbas A.A., ix, xii, 26, 30, 51, 54, 69{71, 74, 92, 127, 128, 134, 161{164, 199, 201, 252, 255{259, 261, 267, 318, 323, 344{ 350, 352, 354, 359, 361, 362, 364, 365, 371, 372 Kiryakova V.S., 162, 202, 363, 365, 366 Ko A., 254, 374 Kober H., 92, 342, 344, 360, 365 Koh E.L., 343, 352, 360, 365 Koranne P.S., 260, 374 Koranne V.D., 92, 371 Koul C.L., 56, 68, 370 Kratzel E., 69, 318, 320, 352, 365 Kumar R., 355, 366 Kumbhat R.K., 91, 129, 161, 258, 366, 372 Kushwaha R.S., 131, 372 Laddha R.K., 69, 366 Lawrynowicz J., 67, 366 Lee W.Y., 343, 348, 366 Li C.K., 343, 365 Linares M., 343, 348, 358, 366 Lions J.L., 343, 366 Littlewood J.E., 343, 362 Love E.R., 256{258, 350, 366, 368 Lowndes J.S., 348, 366 Luchko Yu.F., 128, 199, 202, 366, 375 Luke Y.L., 62, 366 Maeda N., 259, 371 Magnus W., 3, 25, 32, 35, 41, 42, 48, 62{66, 69, 82, 108, 207, 216, 252, 254, 259, 263, 264, 266, 270, 289, 292, 293, 295, 298, 303, 307, 311{314, 325, 349, 361 Mahato A.K., 255, 348, 352, 366 Mahato R.M., 348, 366 Mainra V.P., 254, 367 Malgonde S.P., 92, 164, 343, 348, 352, 367, 371 Manandhar R.P., 351, 367 Marichev O.I., ix, xii, 5, 26, 47, 48, 51, 54, 56, 61, 62, 65, 67{69, 71, 74, 134, 164, 199, 207, 208, 213, 216, 219, 223, 227, 241, 252, 255{259, 261, 267, 273, 307, 326, 327, 346{348, 350, 354, 359, 367, 370, 371, 375 Marrero I., 343, 358
Author Index
Martic B., 343, 351, 367 Masood S., 198, 200, 363, 367 Mathai A.M., xii, 19, 26, 27, 30, 62, 67{69, 92, 367 Mathur S.L., 67, 367 Mathur S.N., 68, 372 McBride A.C., 91, 161{163, 251, 258, 343, 344, 348, 352, 367, 368 McKellar B.H.J., 350, 368 Mehra A.N., 163, 252, 368 Mehra K.N., 260, 368 Meijer C.S., 67, 251, 252, 350, 351, 368 Mellin H., 25, 368 Mendez J.M.R., 343, 348, 358, 366, 368, 371 Misra O.P., 199, 200, 252, 368 Mittal P.K., 90, 129, 130, 163, 201, 362, 368 Mittal S.S., 256, 362 Moharir S.K., 131, 368 Moiseev E.I., 353, 368 Munot P.C., 253, 363 Nair V.C., 67, 368 Nasim C., 131, 163, 254, 351, 368 Negrin E.R., 348, 358 Nguyen Thanh Hai, 91, 368 Oberhettinger F., 3, 25, 32, 35, 41, 42, 48, 62{66, 69, 82, 108, 207, 216, 252, 254, 259, 263, 264, 266, 270, 289, 292, 293, 295, 298, 303, 307, 311{314, 325, 349, 361 Okikiolu G.O., 346, 350, 351, 369 Oliver M.L., 67, 369 Olkha G.S., 68, 355, 369 Pandey A.B., 343, 369 Pandey J.N., 199, 348, 353, 360, 369 Parashar B.P., 201, 254, 369 Pathak R.S., x, xii, 67, 68, 92, 199, 252{254, 343, 353, 354, 360, 369 Pincherle S., 25, 369 Prabhakar T.R., 256, 258, 261, 366, 369, 370
383
Prudnikov A.P., x, xii, 5, 26, 43, 47, 48, 56, 61, 62, 67{69, 92, 199, 207, 208, 213, 216, 219, 223, 227, 241, 251, 253, 255, 256, 260, 267, 273, 307, 326, 327, 342, 343, 348, 352, 353, 359, 360, 368, 370 Rai R.B., 252, 369 Raina R.K., 56, 67, 68, 92, 162, 163, 202, 258, 260, 365, 370, 371, 373 Ram J., 69, 258, 371 Rao G.L.N., 254, 256, 260, 352, 370 Rathie P.N., 355, 369 Repin O.A., 258, 364 Rivero M., xi, 70, 352, 359, 364, 370 Rodriguez J., xi, 352, 364, 370 Rodriguez L., xi, 70, 352, 359 Rodriguez-Mesa L., 343, 348, 352, 358 Rooney P.G., ix, x, 73{75, 92, 95, 96, 107, 117, 121, 127, 128, 199, 200, 251, 259, 265, 267{269, 276, 280, 297, 298, 306, 342{345, 347, 349, 350, 362, 370 Sahoo H.K., 343, 369 Saigo M., 26, 30, 69, 70, 92, 127, 128, 161{ 163, 201, 202, 253, 258{260, 323, 352, 354, 361, 364, 365, 370{373 Saksena K.M., 252, 253, 255, 351, 366, 371 Samko S.G., ix, xii, 51, 54, 69, 71, 74, 134, 164, 199, 252, 255{259, 261, 267, 346{ 348, 350, 371 Sanchez Quintana A.M., 348, 368, 371 Saxena R.K., xii, 19, 26, 27, 30, 62, 67{69, 91, 92, 126, 127, 129, 131, 161, 201, 253, 257, 258, 260, 343, 346, 348, 351, 359, 363, 367, 368, 371, 372 Saxena Raj.K., 92, 131, 199, 348, 363, 367, 368, 371 Saxena S., 253, 371 Saxena V.P., 131, 372 Schuitman A., 258, 343, 348, 359, 372 Schwartz A.L., 348, 372 Sethi P.L., 348, 372 Shah M., 67, 372 Sharma C.K., 254, 372 Sharma K.C., 200, 351, 372 Sharma O.P., 68, 199, 372 Shlapakov S.A., xi, 92, 127, 128, 318, 352, 361, 364, 365, 372
Author Index
384
Singh R., 90, 129, 163, 372 Singh Y., 161, 372 Skibinski P., 26, 67, 68, 372 Skurnik U., 353, 368 Sneddon I.N., ix, x, 43, 48, 68, 92, 251, 342, 344, 346, 373 Socas Robayna M.-M., 348, 368 Soni K., 343, 346, 347, 373 Soni R.P., 346, 373 Soni S.L., 67, 373 Spratt W.J., 161, 162, 251, 368 Srivastava A., 67, 68, 362, 373 Srivastava H.M., ix, x, xii, 19, 26, 30, 36, 39, 47, 56, 61, 67{69, 131, 161, 163, 253, 254, 258, 260, 353, 354, 360, 361, 373 Srivastava K.J., 252, 355, 373 Srivastava K.N., 259, 374 Srivastava M.M., 68, 374 Stein E.M., 265, 374 Swaroop R., 256, 374
Tricomi F.G., 3, 25, 32, 35, 41, 42, 48, 62{66, 69, 82, 108, 207, 216, 252, 254, 259, 263, 264, 266, 270, 289, 292, 293, 295, 298, 303, 307, 311{314, 325, 343, 349, 361, 374 Trujillo J.J., xi, 70, 344{347, 352, 359, 364, 365, 370
Taxak R.L., 68, 374 Titchmarsh E.C., x, 43, 57, 68, 108, 251, 266, 273, 280, 325, 342, 343, 349, 351, 353, 354, 374 Tiwari A.K., 253, 254, 260, 374 Trebels W., 348, 361
Yakubovich S.B., 91, 128, 199, 368, 375
Upadhyay S.K., 343, 369 Varma R.S., 252, 374 Verma C.B.L., 90, 374 Verma R.U., 129, 131, 199{201, 374 Virchenko N.O., 164, 374 Vu Kim Tuan, x, xii, 91, 199, 255, 343, 344, 346, 350, 359, 367, 374, 375 Vyas O.D., 254, 354, 373 Watson G.N., 355, 375 Widder D.V., 43, 200, 251, 252, 259, 351, 375 Wimp J., 256, 257, 375 Wong C.F., 199, 375
Zayed A.I., xii, 342, 343, 351{353, 375 Zemanian A.H., 164, 199, 251, 343, 352, 365, 375 Zhuk V.A., 258, 365
SUBJECT INDEX Bessel function of rst kind, 48, 64 of second kind (Neumann function), 64, 289 Bessel modi ed function of rst kind, 307 of third kind (Macdonald function), 64, 307 integral representation, 66 Bessel type functions, 64{66 Bessel type transform K , 313, 352 L;2-theory, 315 L;r -theory, 317 Bessel type transform L(m) , 313, 352 L;2-theory, 316 L;r -theory, 319 Bessel's cut function, 276 Bessel{Maitland function, 65, 337 generalized, 65, 337
Euler{Mascheroni constant, 311 exceptional set of G, 166 exceptional set of H, 86
F
-transform, 219 L;2-theory, 220 L;r -theory, 220 generalization, 221 L;2-theory, 221{222 L;r -theory, 222 modi cation, 255 1 F 2 -transform, 223 L;2-theory, 223{224 L;r -theory, 224 inversion formulas, 225 modi cation, 225 L;2-theory, 225{226 L;r -theory, 226 inversion formulas, 226{227 2 F 1 -transform, 227 L;2-theory, 228{229 L;r -theory, 229{230 further generalization, 236 L;2-theory, 236{237 L;r -theory, 237{238 generalization, 230 L;2-theory, 231{232 L;r -theory, 232{233 modi ed, 233, 256 L;2-theory, 234{235 L;r -theory, 235 2 F 2 -transform, 260 p F q -transforms, 240 p F p -transform, 241 L;2-theory, 242{243 L;r -theory, 243 p F p+1 -transform, 241 L;2-theory, 243{244 L;r -theory, 244 inversion formulas, 244{245 1
Cauchy principal value, 273 characteristic function, 273, 317 class A, 73 con uent hypergeometric function of Kummer, 63 of Tricomi, 206, 216 integral representation, 207
D -transform, 216, 255 L;2-theory, 217 L;r -theory, 217
generalization, 218 L;2 -theory, 218 L;r -theory, 219 elementary operators, 76, 281 L;r -theory, 76, 282 Erdelyi{Kober operator, 267 Erdelyi{Kober type fractional integrals, 74 L;r -theory, 75 377
1
378
F
p p;1 -transform, 241 L;2-theory, 245 L;r -theory, 245{246
Fourier cosine transform, 263, 343 L;r -theory, 270{271 inversion formulas, 271{272 Fourier sine transform, 263, 343 L;r -theory, 271 inversion formulas, 271{272 fractional integrals generalized, 129 fractional integrals and derivatives Riemann{Liouville, 51{52 G-function, 62 as symmetrical Fourier kernel, 198 as unsymmetrical Fourier kernel, 197{ 198 G-transform, 71, 165 L;2-theory, 166{167 L;r -theory, 168{172 inversion formulas, 172{173 modi ed, 173 1 G -transform, 173 L;r -theory, 175{178 inversion formulas, 178{179 G2-transform, 173 L;r -theory, 179{182 inversion formulas, 182{183 G;-transform, 173 L;r -theory, 183{187 inversion formulas, 187{188 1 G;-transform, 173 L;r -theory, 188{192 inversion formulas, 192 G2;-transform, 173 L;r -theory, 193{196 inversion formulas, 196{197 gamma function asymptotic behavior at in nity, 3 asymptotic estimate near pole, 6 functional equations, 32, 35 Gauss{Legendre multiplication formula, 41 Legendre duplication formula, 307 multiplication formula, 41 re ection formula, 32 Gegenbauer polynomial, 259 Gegenbauer transform, 259 general integral transform, 82 L;2-theory, 82{86
Subject Index
H-function, 1 algebraic asymptotic expansions at in nity, 9{12, 28 algebraic asymptotic expansions at zero, 19{21 analyticity, 5 as symmetrical Fourier kernel, 26 as unsymmetrical Fourier kernel, 126 asymptotic estimates for large positive x, 27 Braaksma's results, 28{30 contiguous relations, 36 di erential formulas, 33{35 elementary properties, 31{32 existence theorem, 4{5 expansion formulas, 39{40 exponential asymptotic expansions at in nity the case n = 0, 17{19 the case > 0; a = 0, 12{17 exponential asymptotic expansions at zerothe case m = 0, 24{25 the case < 0; a = 0, 21{23 nite series relations, 36{39 fractional integration and di erentiation of, 52{55 generalized Hankel transform of, 51 generalized Laplace transform of, 47{48 Hankel transform of, 49 hypergeometric function, 63 integral formulas, 56{62 integral representation, 77{81 Laplace transform of, 45{47 Mellin transform of, 43{44 multiplication relation, 41{42 multiplication theorem, 39{40 power series expansions, 6 power-logarithmic series expansions, 8{9 recurrence relations, 36{39 reduction formulas, 31 self-reciprocal, 68 special cases, 62{66 symmetricity, 31 transformation of in nite series, 42 translation formula, 21 H -transform, 71 L;2-theory, 86{90 L;r -theory the case a = = 0; Re() = 0, 93{97 the case a = = 0; Re() < 0, 97{100 the case a = 0; > 0, 100{104 the case a = 0; < 0, 104{106 the case a > 0, 107{108 the case a1 > 0; a2 > 0, 109{111
379
Subject Index
the case a1 > 0; a2 = 0, 112{114 the case a1 = 0; a2 > 0, 114 the case a > 0; a1 > 0; a2 < 0, 115{117 the case a > 0; a1 < 0; a2 > 0, 117{118 generalized, 91 inversion relation the case = 0, 118{121 the case 6= 0, 121{126 Mellin transform of, 72 modi cation, 129 inversion formula, 130 special cases, 90, 126, 128, 129, 131 with unsymmetrical Fourier kernel, 128 1 H -transform, 133 L;r -theory, 135{139 inversion formulas, 140 2 H -transform, 133 L;r -theory, 140{144 inversion formulas, 144 H ; -transform, 133 L;r -theory, 145{149 inversion formulas, 149{150 1 H ; -transform, 133 L;r -theory, 150{154 inversion formulas, 154{155 2 H ; -transform, 133 L;r -theory, 155{159 inversion formulas, 159{160 Hankel transforms, 48, 263, 342 L;2-theory, 331{332 L;r -theory, 263{269, 333 inversion formulas, 269{270, 334{335, 342 extended, 276, 344 L;r -theory, 277 inversion formulas, 277{280 generalized, 51, 74, 343, 346 L;r -theory, 75, 283{284 inversion formulas, 284 two-weighted estimate, 343 Hankel type transform, 280, 344, 346 L;r -theory, 281{282 inversion formulas, 283 particular case, 344 Hankel{Cli ord transforms, 285, 347, 348 L;r -theory, 287{288 distributional, 348 inversion formulas, 288{289 modi ed, 348
Hankel{Schwartz transforms, 285, 347, 348 L;r -theory, 285{287 inversion formulas, 286{287 Hardy transforms, 352 inversion formulas, 353 modi ed, 325 L;2-theory, 330{331 L;r -theory, 332{333 inversion formulas, 334 Hardy{Titchmarsh transform generalized, 325 L;2-theory, 329{330 L;r -theory, 332 inversion formulas, 334 special case, 353 Hilbert even and odd transforms, 272, 343 L;r -theory, 274 integral representations, 273{274 inversion formulas, 275{276 Holder inequality, 96 hypergeometric function Gauss, 62 generalized, 62 integral in a Cauchy sense, 280, 298 integral transforms with Bessel{Maitland function, 354 Kober fractional operators, 252 Kober operators composition, 257 Laplace transform, 43 L;r -theory, 206 connecting with Hankel transform, 343 further modi cation of generalized, 204 L;2-theory, 205 L;r -theory, 205 generalized, 47, 74, 251 L;r -theory, 75 inversion formula, 251 in L2 (R+ ), 251 inversion formula, 43, 255 modi cation of generalized, 203 L;2-theory, 203{204 L;r -theory, 204 Lommel function, 64, 325 Lommel{Maitland transform, 337, 354 L;2-theory, 339{340 L;r -theory, 341{342 particular case, 354 special case of L;2-theory, 340{341 L;r -theory, 342
380
Love operators, 256{257 boundedness, 257 Lowndes operators, 347 Macdonald function, 64, 307 MacRobert E-function, 64 McBride space Fr; , 161 Meijer K -transform, 307, 350 L;2-theory, 309{310 L;r -theory, 311{312 modi ed, 351 Meijer M k;m -transform, 206, 251 L;2-theory, 207{208 L;r -theory, 208 inversion formula, 252 Mellin transform, 43, 72 inversion formula, 43 multiplier theorem, 74 of Erdelyi{Kober type fractional integrals, 75 of generalized Hankel transform, 75 of generalized Laplace transform, 75 Mellin transform on L;r , 73 properties, 73 Mellin{Barnes type integral, 1 Mittag-Leer function, 65 modi ed Bessel type transform, 321, 352 L;2-theory, 322{323 L;r -theory, 324 Neumann function, 64, 289 parabolic cylinder function, 216 Parseval relation, 128 Pochhammer symbol, 42 psi function, 6 reciprocal relations by Bateman, 354 by Hardy, 349, 352 by Meijer, 350 by Titchmarsh, 353 reciprocal transforms, 349 Saigo operators, 258 on Lp , 258 on F;r ; F0;r , 258
Subject Index
Schwartz inequality, 83 space L;1 , 75 space L;r , 71 Stieltjes transform, 239 generalized, 238, 259 L;2-theory, 239{240 L;r -theory, 240 generalization, 260 inversion, 259 special case, 259 Stirling relation, 3 Struve function, 295 Struve transform, 299, 349 L;r -theory, 301{303 inversion formulas, 305{306, 349 modi ed, 350 Titchmarsh transform, 325, 353 Varma transform, 208, 252 L;2-theory, 209 L;r -theory, 209{210 modi ed, 211 L;r -theory, 212 representations, 253 Watson function, 355 Watson{Wright transform, 355 Whittaker function, 64, 206 Whittaker transform generalized, 212, 253{254 L;2-theory, 213{214 L;r -theory, 214 modi cation, 214 modi cation L;2-theory, 215 modi cation L;r -theory, 215{216 Wright function, 65 Wright transform, 246 L;2-theory, 247 L;r -theory, 247{250 inversion formulas, 251
Y-transform, 289, 349
L;r -theory, 292{294
inversion formulas, 295{298 modi ed, 350
SYMBOL INDEX : parameter for G-function, 166 : parameter for H-function, 77 0: parameter for G-function, 172 0: parameter for H-function, 119 : parameter for G-function, 166 : parameter for H-function, 77 0 : parameter for G-function, 172 0 : parameter for H-function, 119 ;(z): Stirling relation of gamma function, 3
: Euler{Mascheroni constant, 311
nr; : seminorm on Fr; , 162 : parameter for G-function, 166 : parameter for H-function, 2 : di erential operator, 162 : parameter for H-function, 2 ( n)(z): generalized Macdonald function, 66, 67, 313 ( ) ; (z): generalized Macdonald function, 66, 321 : parameter for G-function, 166 : parameter for H-function, 2 : parameter for H-function, 2 a : elementary operator, 123 : parameter of H-function asymptotic estimate, 11, 12, 16 : parameter of H-function asymptotic estimate, 20, 21, 23 ;x(t): function, 279 ;m (x): function, 306 x (t): characteristic function, 273, 317 ;k;m(x): special case of G-function, 200 (a; c; x): con uent hypergeometric function of Tricomi, 206 (z): Wright's generalized hypergeometric p q function, 65 (z): psi function, 6
;;(z):
function, 354
p q : Wright transform, 246
k kr : norm on Lr (R ), 72 k k;r : norm on L;r , 71 k k;1 : norm on L;1, 75 +
(k f)(x): Mellin convolution, 161
(k; ai); i 1;p : parameter sequence, 41 (k; bj ); j 1;q : parameter sequence, 41 [X; Y ]: collection of bounded linear operators, 74 [X]: collection of bounded linear operators, 74 A0: coecient of H-function expansion, 13 A0 : coecient of H-function expansion, 22 a : parameter for G-function, 166 a : parameter for H-function, 2 a1 : parameter for G-function, 166 a1 : parameter for H-function, 2 a2 : parameter for G-function, 166 a2 : parameter for H-function, 2 aik : pole of ;(1 ; ai ; is), 1, 8 (a)k : Pochhammer symbol, 42 A: class, 73 bjl : pole of ;(bj + j s), 1, 7 b;1: Hankel{Cli ord transform, 285 b;2: Hankel{Cli ord transform, 285 C1: coecient of H-function expansion, 17 C2: coecient of H-function expansion, 17 385
Symbol Index
386
C : elementary operator, 73 Ck(x): Gegenbauer polynomial, 259 C1: coecient of H-function expansion, 24 C2: coecient of H-function expansion, 24 c : parameter for H-function, 2, 41 c0: coecient of H-function expansion, 12, 17 c0 : coecient of H-function expansion, 21, 24 C : eld of complex numbers, 1 D1 : coecient of H-function expansion, 17 D2 : coecient of H-function expansion, 17 D1 : coecient of H-function expansion, 24 D2 : coecient of H-function expansion, 24 : Riemann{Liouvillefractional derivative, D0+ 52 D; : Riemann{Liouville fractional derivative, 52 d0: coecient of H-function expansion, 12, 17 d0: coecient of H-function expansion, 21, 24 D (z): parabolic cylinder function, 216 D : D -transform, 216 D ;; : modi ed D -transform, 218 E(z): auxilary function of H-function expansion, 12 E (z): auxilary function of H-function expansion, 21 E(a1; ; ap : b1; ; bq : z): MacRobert Efunction, 64 EG : exceptional set for G, 166 EH : exceptional set for H, 86 E; (z): Mittag-Leer function, 65 F0 (a; z): hypergeometric function, 63 1 F1 (a; c; z): con uent hypergeometric function of Kummer, 63 2 F1 (a; b; c; z): Gauss hypergeometric function, 62, 63 p Fq (a1 ; ; ap ; b1; ; bq ; z): general hypergeometric function, 62, 64 F3(a; a0; b; b0; c; x; y): Appell function, 69 k 1 F 1 : 1 F 1-transform, 219 ; 1 F 1 : modi ed 1 F 1-transform, 221 1
F : generalization of modi ed F -transform, 255 F : F -transform, 223 F ;: modi ed F -transform, 225 F : F -transform, 227 F : F -transform, 227 F ;: modi ed F -transform, 230 F ; : modi ed F -transform, 230 F : modi ed F -transform, 233 F : modi ed F -transform, 233 F ;: generalization of modi ed F -transform, 236 ; F : generalization of modi ed F -transform, 236 F : generalization of modi ed F -transform, 255 p F p: p F p -transform, 241 p F p; : p F p; -transform, 241 p F p : p F p -transform, 241 p F q : p F q -transform, 240 1
1
1
1
2
1
2
2
1
1
2
1
2
1
2
1
2
1
2
1
2
;
2
1 1 1 2 1 1; 1
2
2; 1
2 2
2
1
2
2
1
2
2
1
2
1
2
1
2
1
2
1
1
1
1
1
+1
+1
F 0; 1; 2 : Hankel type transform, 346 Fr; : McBride space, 161 F0r; : McBride space, 163 Fr;;a : space, 162 F: Fourier transform, 73 Fc : Fourier cosine transform, 263 Fs : Fourier sine transform, 263 F(cm) : transform relating to Fc, 275 F(sm) : transform relating to Fs, 275
Gm;n p;q (z): Meijer G-function, 62 ga(t): function, 82, 96, 124 g;x(t): function, 265, 277, 323 gm;x (t): function, 319 G: G-transform, 71, 165 G1: modi ed G-transform, 173 G2: modi ed G-transform, 173 G;: modi ed G-transform, 173 G1;: modi ed G-transform, 173 G2;: modi ed G-transform, 173 Ge : generalized G-transform, 200 G0+: modi cation of G-transform, 201 G;: modi cation of G-transform, 202 G0;0: modi cation of G-transform, 201 G1;0: modi cation of G-transform, 201
Symbol Index
G;;: modi cation of G-transform, 201 G : modi cation of G-transform, 202 G ;: modi cation of G-transform, 202 ;0+
;
G : modi ed G-transform, 202 G : modi ed G-transform, 202 1 2
Gk: Gegenbauer transform, 259 G : modi ed Meijer G-transform, 200 Gm;n p;q (s):
function G, 165
Hi: coecient of H-function expansion, 9 Hj : coecient of H-function expansion, 8 Hikj : coecient of H-function expansion, 8 : coecient of H-function expansion, 7 Hjli m;n (z): H-function, 1 Hp;q Hqn;q +p;n+m (x): G-function as unsymmetrical Fourier kernel, 198 m;p Hp+q;m+n (x): H-function as unsymmetrical Fourier kernel, 126 n;q Hq+p;n+m (x): H-function as unsymmetrical Fourier kernel, 126 H2q;pp;2q (x): H-function as symmetrical Fourier kernel, 26 hi: coecient of H-function expansion, 10 hik : coecient of H-function expansion, 6 hj : coecient of H-function expansion, 19 hjl : coecient of H-function expansion, 6 h1(s): function, 14, 15 ha (t): function, 84, 96 h;x (t): function, 265, 270, 279, 311, 317, 319 h (t): function, 296 H : H -transform, 71 H 1: modi ed H -transform, 133 H 2: modi ed H -transform, 133 H ; : modi ed H -transform, 133 H 1; : modi ed H -transform, 133 H 2; : modi ed H -transform, 133 H : generalized H -transform, 127 H +: even Hilbert transform, 272 H ;: odd Hilbert transform, 272 H ! : modi cation of H -transform, 91 H ;c: modi cation of H -transform, 129 H U;0+: modi cation of H -transform, 160 H U;;: modi cation of H -transform, 160 H 10; : modi cation of H -transform, 164 H 20;0: modi cation of H -transform, 164
387
c : modi cation of H -transform, 161 H c; : modi cation of H -transform, 161 H 0+
H (z): Struve function, 295 H : modi ed Hankel{Cli ord transform, 348 0 ; H ; : Watson {Wright transform, 355 ;0 ; H : Hankel transform, 48, 263 H k; : generalized Hankel transform, 51, 74 H ;l : extended Hankel transform, 276 H ;; : product of Hankel transforms, 345 H ;;$;k; : Hankel type transform, 280
H : Struve transform, 299 H; : modi ed Struve transform, 350 H [f(at); x]: special case of Hankel type trans-
form, 344 H; : special case of Hankel type transform, 344 m;n Hp;q (s): function H, 1 h;1: Hankel{Schwartz transform, 285 h;2: Hankel{Schwartz transform, 285
: Riemann{Liouville fractional integral, I0+ 51 I; : Riemann{Liouville fractional integral, 51 I0+; ; : Erdelyi{Kober type fractional integral, 74 I;;; : Erdelyi{Kober type fractional integral, 74 I ; : Erdelyi{Kober operator, 267 ; ; : Saigo operator, 258 I0+ I; ; ; : Saigo operator, 258 I (z): modi ed Bessel function of rst kind, 307 I ;;m : Kiryakova operator, 162 + I; : Kober fractional operator, 252 c 1 I 0+ (a; b): Love operator, 256 c 1 I ; (a; b): Love operator, 256 c 2 I 0+ (a; b): Love operator, 256 c 2 I ; (a; b): Love operator, 257 Im;n p;q : Kiryakova operators, 163, 202
J (z): Bessel function of rst kind, 48, 64 J ; (z): Bessel{Maitland function, 65, 337 (z): generalized Bessel{Maitland function, J; 65, 337 J (z): special case of generalized Bessel{Maitland function, 337
Symbol Index
388
J; (z): Lommel function, 325 J;l (z): Bessel's cut function, 276
(z): generalized Bessel{Maitland funcJ; tion, 337 Ja;b;c(x): kernel function for Titchmarsh transform, 353 Ja;b;c;! (z): kernel function for generalized Hardy{ Titchmarsh transform, 325
; J : modi ed Bessel{Maitland transform, 354
; J : Bessel{Maitland transform, 354 J; : integral transform, 355 Ja;b;c: Titchmarsh transform, 353 J ; : particular case of Lommel{Maitland transform, 354 J;l : extended Hankel transform, 325 J; : modi ed Hardy transform, 325 J : particular case of Lommel{Maitland transform, 337
J; : Lommel{Maitland transform, 337 Ja;b;c;! : generalized Hardy{Titchmarsh transform, 325 Jk (; ): Lowndes operator, 347
L: Laplace transform, 43, 206 L;1 : Laplace inversion, 43, 255 Lk; : generalized Laplace transform, 47, 74 L ;k : Laplace type transform, 203 L ;k;; : Laplace type transform, 204
K (z): modi ed Bessel function of third kind (Macdonald function), 64, 66, 307 m;p Kp+q;m+n (x): G-function as unsymmetrical Fourier kernel, 197{198 ; K; : Kober fractional operator, 252 K ;;m : Kiryakova operator, 162 K : general integral transform, 82, 107 Km;n p;q : Kiryakova operators, 163, 202 K : Meijer type transform, 352 K : Bessel type transform, 313 K : Meijer K -transform, 307 K; : modi ed Meijer K -transform, 351 K; ;! : modi ed Meijer K -transform, 351
q;x(t): function, 306
Lr (R+ ): Lebesgue space, 72 Lqp (0; d): weighted Lebesgue space, 257 Lrp (e; 1): weighted Lebesgue space, 257 Ln;; m : modi cation of Erdelyi{Kober type operator, 251 L : axisymmetric di erential operator, 163 L(; ) : modi ed Bessel type transform, 321 L(m): Bessel type transform, 313
L;1 : Mellin{Barnes contour, 2 L+1 : Mellin{Barnes contour, 2 Li 1 : Mellin{Barnes contour, 2 L;r : Rooney space, 71 L;1 : Rooney space, 75
M : elementary operator, 76 M k;m: Meijer transform, 206 M: Mellin transform, 43, 72 (Mf)( + it): Mellin transform of f 2 L;r , 73 M;1 : Mellin inversion, 43 Na : elementary operator, 281 Nm : integral transform, 162 p.v.: Cauchy principal value, 273
R: elementary operator, 76 r;x(t): function, 296 Rk;; : integral transform, 347 R: eld of real numbers, 2 R+ : half real line, 1 R: generalized fractional integral, 129 Rk (; ): Lowndes operator, 347 R( ; ; m): Erdelyi{Kober type fractional integral, 129 s; (z): Lommel function, 64 S; q;k;m: generalized Whittaker transform, 254 S : generalized fractional integral, 129 S : modi ed Struve transform, 350 S; ; : generalized Hankel transform, 346 S (a;b;y ; ; ): generalized Hankel transform, 348 S: Stieltjes transform, 239 S : generalized Stieltjes transform, 260 S ;; : generalized Stieltjes transform, 238
Symbol Index
T : general integral transform, 107 U n: sequence of di erential operators, 252 V k;m: Varma transform, 208 V k;m: modi ed Varma transform, 211 V k;m: modi ed Varma transform, 211 1 2
W : elementary operator, 76 W; (z): Whittaker function, 64, 206 w;0 (x): Watson function, 355
389
; 0 (x): generalized Watson function, 355 w; ; W ;0 : Watson transform, 355 W k; : generalized Whittaker transform, 212 W k; ;; : modi cation of generalized Whittaker transform, 214 0
Y (z): Bessel function of second kind (Neumann function), 64, 289 Y : Y-transform, 289 Y; : modi ed Y-transform, 350 Z (z): generalized Macdonald function, 66, 313
