English

The alternate congruo-harmonic series Part 2 -- Accelerations of convergence

Classical Analysis and ODEs 2022-07-06 v1

Abstract

For every couple (p;q) of strictly positive integers, the `` alternate congruo-harmonic '' series parametrized by (p;q), whose general term is (-1)^k/(pk+q), converges infra-linearly and very slowly. On the basis of a generalized continued fraction expansion of the partial rest of the series, this paper elaborates a family of algorithms which accelerate its convergence. The convergence speed of the sequences generated by these algorithms are compared. A precise asymptotic analysis is conducted, which reveals the possibility to accelerate the convergence either infra-linearly (but with an infinite diversity of possible speeds), or linearly (with a convergence rate that appears universal relatively to (p;q)), or super-linearly, by means of sequences extractions. Several open problems are also discussed, which concern the relative `` performance '' of the algorithms thus built and the possible optimality of some of them.

Keywords

Cite

@article{arxiv.2207.01854,
  title  = {The alternate congruo-harmonic series Part 2 -- Accelerations of convergence},
  author = {David Pouvreau},
  journal= {arXiv preprint arXiv:2207.01854},
  year   = {2022}
}

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in French language