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arXiv · 1809.08794

Asymptotics of a Gauss hypergeometric function with large parameters, IV: A uniform expansion

R B Paris
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Abstract

We consider the uniform asymptotic expansion for the Gauss hypergeometric function \[F(a+\epsilon\lambda,m;c+\lambda;x),\qquad \lambda\to+\infty\] for $x<1$ and positive integer $m$ when the parameter $\epsilon>1$ and the constants $a$ and $c$ are supposed finite. When $m=1$, we employ the standard procedure of the method of steepest descents modified to deal with the situation when a saddle point is near a simple pole. It is shown that it is possible to give a closed-form expression for the coefficients in the resulting uniform expansion. The expansion when $m\geq 2$ is obtained by means of a recurrence relation. Numerical results illustrating the accuracy of the resulting expansion are given.

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R B Paris. 2018-09-24. Asymptotics of a Gauss hypergeometric function with large parameters, IV: A uniform expansion. https://arxiv.org/abs/1809.08794

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