## Abstract The discrete complex image method has proved to be one of the most efficient techniques to evaluate Green's functions for multilayered media, particularly in the near‐ and intermediate‐field regions. Although the extraction of surface waves extends its validity to the far field, it suff
Fast Evaluation of Holonomic Functions Near and in Regular Singularities
✍ Scribed by Joris van der Hoeven
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 466 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0747-7171
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✦ Synopsis
A holonomic function is an analytic function, which satisfies a linear differential equation Lf = 0 with polynomial coefficients. In particular, the elementary functions exp, log, sin, etc., and many special functions such as erf, Si, Bessel functions, etc., are holonomic functions.
In a previous paper, we have given an asymptotically fast algorithm to evaluate a holonomic function f at a non-singular point z on the Riemann surface of f , up to any number of decimal digits while estimating the error. However, this algorithm becomes inefficient, when z approaches a singularity of f .
In this paper, we obtain efficient algorithms for the evaluation of holonomic functions near and in singular points where the differential operator L is regular (or, slightly more generally, where L is quasi-regular-a concept to be introduced below).
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