A double expansion formula for generalized multivariable Gimel-function

involving Jacobi polynomials and Bessel functions

Frédéric Ayant

Teacher in High School , FranceE-mail :fredericayant@gmail.com

ABSTRACTIn this paper, we present a double expansion formula for the generalized multivariable Gimel-function involving Jacobi polynomials and Bessel functions.

KEYWORDS : Multivariable Gimel-function, multiple integral contours, Jacobi polynomial, Bessel function, Double expansion serie.

2010 Mathematics Subject Classification. 33C99, 33C60, 44A20

1. Introduction and preliminaries.

Throughout this paper, let and be set of complex numbers, real numbers and positive integers respectively.Also .

The subject of expansion formulae and Fourier series of special functions occupies a large place in the literature ofspecial functions. Certain double expansion formulae and double Fourier series of generalized hypergeometric functionsplay an important rôle in the development of the theories of special functions and two- dimensional boundary valueproblems. In this paper, we establish a double expansion formula for generalized multivariable Gimel-function.

We define a generalized transcendental function of several complex variables.

= (1.1)

with

. . . .

. . . .

. . . .

(1.2)

and

(1.3)

1) stands for .

2) and verify :

.

3) .

4)

5)

The contour is in the - plane and run from to where if is a real number with

loop, if necessary to ensure that the poles of

, to

the right of the contour and the poles of

, lie to the left of the

contour . The condition for absolute convergence of multiple Mellin-Barnes type contour (1.1) can be obtained of thecorresponding conditions for multivariable H-function given by as :

where

(1.4)

Following the lines of Braaksma ([2] p. 278), we may establish the the asymptotic expansion in the followingconvenient form :

,

, where :

and

Remark 1.If and

, then the generalized multivariable Gimel-function reduces in the generalizedmultivariable Aleph- function ( extension of multivariable Aleph-function defined by Ayant [1]).

Remark 2.

If and , then the generalized multivariable Gimel-function reduces in a generalized

multivariable I-function (extension of multivariable I-function defined by Prathima et al. [7]).

Remark 3.If and

, then the generalized multivariable Gimel-function reduces in generalized ofmultivariable I-function (extension of multivariable I-function defined by Prasad [6]).

Remark 4.If the three above conditions are satisfied at the same time, then the generalized multivariable Gimel-function reduces inthe generalized multivariable H-function (extension of multivariable H-function defined by Srivastava and panda [8,9]).

In your investigation, we shall use the following notations.

(1.5)

(1.6)

(1.7)

(1.8)

(1.9)

(1.10)

(1.11)

(1.12)

2. Required results.

In this section, we give four formulae. These results will be used in the following sections.

Lemma 1. ([4], p. 1240, Eq. 4)

(2.1)

provided

Lemma 2. (see Luke,[5])

(2.2)

provided .

The orthogonality property of the Jacobi polynomials [3].

Lemma 3.

(2.3)

provided

Orthogonality property for Bessel’s function [5]

Lemma 3.

(2.4)

provided

3. Main integrals.

In this section, we establish two integrals.

Theorem 1.

(3.1)

provided

,

where is defined by (1.4).

Proof

To prove the theorem 1, we replace the generalized multivariable Gimel-function by this multiple integrals contour withthe help of (1.1), change the order of integrations which is justified under the conditions mentioned above. We get

(3.2)

Evaluate the inner integral with the help of lemma 1 and interpreting the Mellin-Barnes multiple integrals contour interms of the multivariable Gimel-function, we get the desired result (3.1).

Theorem 2.

(3.3)

provided

,

where is defined by (1.4).

ProofTo prove the theorem 2, we replace the generalized multivariable Gimel-function by this multiple integrals contour withthe help of (1.1), change the order of integrations which is justified under the conditions mentioned above. We get

(3.4)

Evaluate the inner integral with the help of lemma 2 and interpreting the Mellin-Barnes multiple integrals contour interms of the multivariable Gimel-function, we get the desired result (3.3).

4. Double expansion formula.

The double expansion formula to be establish is

Theorem 3.

(4.1)

where

(4.2)

(4.3)

(4.4)

valid under the existence conditions mentioned in (3.1) and (3.3).

ProofTo establish (4.1), let

(4.5)

The above equation is valid, since is continuous and bounded variation in the region .Multiplying both sides of (4.5) by , integrating with respect to from 1 to and using the (2.4) and(3.3), we obtain

(4.6)

where

(4.7)

(4.8)

Multiplying both sides of (4.6) by , integrating with respect to from -1 to 1 and using(2.3) and (3.1), we obtain

(4.9)

where

(4.10)

(4.11)

(4.12)

Finally substituting the value of in (4.5), we obtain the desired result (4.1).

5. Conclusion.

Since on specializing the parameters of generalized Gimel-function of several variables yield almost all specialfunctions appearing in Applied Mathematics and Physical Sciences. Therefore the result presented in this study is of ageneral character and hence may encompass several cases of interest.

REFERENCES.

[1] F. Ayant, An integral associated with the Aleph-functions of several variables. International Journal ofMathematics Trends and Technology (IJMTT), 31(3) (2016), 142-154.

[2] B.L.J. Braaksma, Asymptotics expansions and analytic continuations for a class of Barnes-integrals, CompositioMath. 15 (1962-1964), 239-341.

[3] A. Erdelyi, W. Magnus, F. Oberhettinger transforms and F.G. Tricomi, Tables of integrals, Vol II, McGraw-Hill, NewYork (1954).

[4] I.S. Gradsteyn and I.M. Ryzhik, Tables of integrals, Series and Product, Academic press, New York (1980).

[5] Y.L. Luke, Integrals of Bessel functions, McGraw Hill, New York (1962).

[6] Y.N. Prasad, Multivariable I-function , Vijnana Parishad Anusandhan Patrika 29 (1986) , 231-237.

[7] J. Prathima, V. Nambisan and S.K. Kurumujji, A Study of I-function of Several Complex Variables, InternationalJournal of Engineering Mathematics, Vol (2014), 1-12.

[8] H.M. Srivastava and R. Panda, Some expansion theorems and generating relations for the H-function of severalcomplex variables. Comment. Math. Univ. St. Paul. 24 (1975),119-137.

[9] H.M. Srivastava and R.Panda, Some expansion theorems and generating relations for the H-function of severalcomplex variables II. Comment. Math. Univ. St. Paul. 25 (1976), 167-197.