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Approximations for the Bessel and Airy functions with an explicit error term

Published online by Cambridge University Press:  01 May 2014

Ilia Krasikov*
Affiliation:
Department of Mathematical Sciences, Brunel University, Uxbridge UB8 3PH, United Kingdom email [email protected]

Abstract

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We show how one can obtain an asymptotic expression for some special functions with a very explicit error term starting from appropriate upper bounds. We will work out the details for the Bessel function $J_\nu (x)$ and the Airy function ${\rm Ai}(x).$ In particular, we answer a question raised by Olenko and find a sharp bound on the difference between $J_\nu (x)$ and its standard asymptotics. We also give a very simple and surprisingly precise approximation for the zeros ${\rm Ai}(x).$

Type
Research Article
Copyright
© The Author 2014 

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