English

Chebyshev approximation of $x^m (-\log x)^l$ in the interval $0\le x \le 1$

Classical Analysis and ODEs 2024-08-28 v1

Abstract

The series expansion of xm(logx)lx^m (-\log x)^l in terms of the shifted Chebyshev Polynomials Tn(x)T_n^*(x) requires evaluation of the integral family 01xm(logx)ldx/xx2\int_0^1 x^m (-\log x)^l dx / \sqrt{x-x^2}. We demonstrate that these can be reduced by partial integration to sums over integrals with exponent m=0m=0 which have known representations as finite sums over polygamma functions.

Keywords

Cite

@article{arxiv.2408.15212,
  title  = {Chebyshev approximation of $x^m (-\log x)^l$ in the interval $0\le x \le 1$},
  author = {Richard J. Mathar},
  journal= {arXiv preprint arXiv:2408.15212},
  year   = {2024}
}

Comments

9 pages, no figures. Integrals table in the anc directory