Derivatives of Humbert confluent hypergeometric functions with respect to their parameters

Fuente: arXiv
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Auteurs principaux: Shehata, Ayman, Sahin, Recep, Yagcı, Oguz, Moustafa, Shimaa I.
Format: Preprint
Publié: 2021
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author Shehata, Ayman
Sahin, Recep
Yagcı, Oguz
Moustafa, Shimaa I.
author_facet Shehata, Ayman
Sahin, Recep
Yagcı, Oguz
Moustafa, Shimaa I.
contents Humbert confluent hypergeometric functions of two variables arise in many problems of mathematical physics and applied analysis, yet their behavior with respect to parameters has not been systematically studied. In this paper we investigate derivatives with respect to numerator and denominator parameters for the seven classical Humbert functions Φ{1}, Φ{2}, Φ_{3}, Psi_{1}, Psi_{2}, Ξ_{1} and Ξ_{2}. Using their double series representations together with elementary properties of the Gamma and digamma functions, we derive explicit formulas for first order parameter derivatives and express them in compact form in terms of Srivastava triple hypergeometric function F{3}. By differentiating the underlying partial differential equations, we further obtain simple operator recurrences for derivatives of arbitrary order, which yield closed differentiation and reduction formulas in terms of contiguous Humbert functions. Finally, we indicate how these results lead to Taylor type parameter expansions and illustrate their use with basic numerical examples and plots.
format Preprint
id arxiv_https___arxiv_org_abs_2104_05051
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Derivatives of Humbert confluent hypergeometric functions with respect to their parameters
Shehata, Ayman
Sahin, Recep
Yagcı, Oguz
Moustafa, Shimaa I.
Classical Analysis and ODEs
33C15, 33C20, 33C65, 33D70, 05A30
Humbert confluent hypergeometric functions of two variables arise in many problems of mathematical physics and applied analysis, yet their behavior with respect to parameters has not been systematically studied. In this paper we investigate derivatives with respect to numerator and denominator parameters for the seven classical Humbert functions Φ{1}, Φ{2}, Φ_{3}, Psi_{1}, Psi_{2}, Ξ_{1} and Ξ_{2}. Using their double series representations together with elementary properties of the Gamma and digamma functions, we derive explicit formulas for first order parameter derivatives and express them in compact form in terms of Srivastava triple hypergeometric function F{3}. By differentiating the underlying partial differential equations, we further obtain simple operator recurrences for derivatives of arbitrary order, which yield closed differentiation and reduction formulas in terms of contiguous Humbert functions. Finally, we indicate how these results lead to Taylor type parameter expansions and illustrate their use with basic numerical examples and plots.
title Derivatives of Humbert confluent hypergeometric functions with respect to their parameters
topic Classical Analysis and ODEs
33C15, 33C20, 33C65, 33D70, 05A30
url https://arxiv.org/abs/2104.05051