Inequalities and monotonicity of ratios for generalized hypergeometric function

Abstract

We find two-sided inequalities for the generalized hypergeometric function of the form ${}_{q+1}{F}_q(-x)$ with positive parameters restricted by certain additional conditions. Both lower and upper bounds agree with the value of ${}_{q+1}{F}_q(-x)$ at the endpoints of positive semi-axis and are asymptotically precise at one of the endpoints. The inequalities are derived from a theorem asserting the monotony of the quotient of two generalized hypergeometric functions with shifted parameters. The proofs hinge on a generalized Stieltjes representation of the generalized hypergeometric function. This representation also provides yet another method to deduce the second Thomae relation for ${}_3{F}_2(1)$ and leads to an integral representations of ${}_4{F}_3(x)$ in terms of the Appell function $F_3$. In the last section of the paper we list some open questions and conjectures.

15 pages, this is the form accepted by Journal of Approximation Theory. Many typos corrected, important references added, several remarks added thoughout the paper. Principal results did not change

References in corpus (1)

• Asymptotic approximations for the first incomplete elliptic integral near logarithmic singularity

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