{ "id": "1609.08365", "version": "v1", "published": "2016-09-27T11:55:09.000Z", "updated": "2016-09-27T11:55:09.000Z", "title": "Asymptotics of a Gauss hypergeometric function with large parameters, III: Application to the Legendre functions of large imaginary order and real degree", "authors": [ "R. B. Paris" ], "comment": "14 pages, 4 figures", "categories": [ "math.CA" ], "abstract": "We obtain the asymptotic expansion for the Gauss hypergeometric function \\[F(a-\\lambda,b+\\lambda;c+i\\alpha\\lambda;z)\\] for $\\lambda\\rightarrow+\\infty$ with $a$, $b$ and $c$ finite parameters by application of the method of steepest descents. The quantity $\\alpha$ is real, so that the denominatorial parameter is complex and $z$ is a finite complex variable restricted to lie in the sector $|\\arg (1-z)|<\\pi$. We concentrate on the particular case $a=0$, $b=c=1$, which is associated with the Legendre functions of real degree and imaginary order. The resulting expansions are of Poincar\\'e type and hold in restricted domains of the $z$-plane. An expansion is given at the coalescence of two saddle points. Numerical results illustrating the accuracy of the different expansions are given.", "revisions": [ { "version": "v1", "updated": "2016-09-27T11:55:09.000Z" } ], "analyses": { "subjects": [ "33C05", "34E05", "41A60" ], "keywords": [ "gauss hypergeometric function", "large imaginary order", "real degree", "legendre functions", "large parameters" ], "note": { "typesetting": "TeX", "pages": 14, "language": "en", "license": "arXiv", "status": "editable" } } }