English

Evaluation of Abramowitz functions in the right half of the complex plane

Numerical Analysis 2020-02-19 v1 Numerical Analysis

Abstract

A numerical scheme is developed for the evaluation of Abramowitz functions JnJ_n in the right half of the complex plane. For n=1,,2n=-1,\, \ldots,\, 2, the scheme utilizes series expansions for z<1|z|<1 and asymptotic expansions for z>R|z|>R with RR determined by the required precision, and modified Laurent series expansions which are precomputed via a least squares procedure to approximate JnJ_n accurately and efficiently on each sub-region in the intermediate region 1zR1\le |z| \le R. For n>2n>2, JnJ_n is evaluated via a recurrence relation. The scheme achieves nearly machine precision for n=1,,2n=-1, \ldots, 2, with the cost about four times of evaluating a complex exponential per function evaluation.

Keywords

Cite

@article{arxiv.1906.12023,
  title  = {Evaluation of Abramowitz functions in the right half of the complex plane},
  author = {Zydrunas Gimbutas and Shidong Jiang and Li-Shi Luo},
  journal= {arXiv preprint arXiv:1906.12023},
  year   = {2020}
}

Comments

24 pages, 2 figures