Computing q+1Fq via rational conformal maps
Abstract
It is well-known that certain Möbius (linear fractional) transformations provide analytic continuation of the Gauss hypergeometric function. These transformations work by exchanging the roles of the three regular singular points and $0$, $1$, and ∞ of the Gauss hypergeometric differential equation. Not one of these transformations, however, brings the points e±iπ/3 closer to the origin, and convergence in a neighbourhood of these is also troublesome. In this work, we produce a Maclaurin series in optimal complexity after rational conformal mapping that induces pointwise convergence to any q+1Fq throughout the cut complex plane ℂ∖[1,∞). We show that for the optimal parameter values this series converges faster than an approximate mapped Chebyshev series obtained by the ultraspherical spectral method.
Related
BibTeX
@misc{lopez2026computing,
title = {{Computing $_q+1F_q$ via rational conformal maps}},
author = {John Lopez and Richard Mikael Slevinsky},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.35577},
eprint = {2610.35577},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.35577},
}
RIS
TY - UNPB
TI - Computing _q+1F_q via rational conformal maps
AU - John Lopez
AU - Richard Mikael Slevinsky
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.35577
UR - https://arxiv.org/abs/2610.35577
AB - It is well-known that certain Möbius (linear fractional) transformations provide analytic continuation of the Gauss hypergeometric function. These transformations work by exchanging the roles of the three regular singular points and $0$, $1$, and ∞ of the Gauss hypergeometric differential equation. Not one of these transformations, however, brings the points e^±iπ/3 closer to the origin, and convergence in a neighbourhood of these is also troublesome. In this work, we produce a Maclaurin series in optimal complexity after rational conformal mapping that induces pointwise convergence to any _q+1F_q throughout the cut complex plane ℂ∖[1,∞). We show that for the optimal parameter values this series converges faster than an approximate mapped Chebyshev series obtained by the ultraspherical spectral method.
ER -