`acb_hypgeom_2f1_choose`

Synopsis#include <flint/acb_hypgeom.h>

int acb_hypgeom_2f1_choose(const acb_t z)source

Chooses the method for computing ${}_2F_1$ from the location of $z$ : returns 0 for direct summation, 1 to 5 for the transformation with that index in acb_hypgeom_2f1_transform, or 6 for the corner case.

Direct summation is chosen if $|z| \le 1/4$ , the Pfaff transformation if $|z/(z-1)| \le 1/4$ , the smaller of the two if either is at most $3/4$ , and otherwise the transformation that minimizes the modulus of the new argument, if that modulus is at most $3/4$ ; the remaining region, around $\exp(\pm\pi i/3)$ , is the corner case.

Cite this page

The FLINT team, “acb_hypgeom_2f1_choose (acb_hypgeom.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/acb_hypgeom/acb_hypgeom_2f1_choose.html (generated 2026-11-02).

@misc{flint-doc-acb-hypgeom-acb-hypgeom-2f1-choose,
  author       = {{The FLINT team}},
  title        = {{acb\_hypgeom\_2f1\_choose (acb\_hypgeom.h)}},
  howpublished = {FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev},
  year         = {2026},
  url          = {https://flintlib.org/doc/acb_hypgeom/acb_hypgeom_2f1_choose.html},
  note         = {Generated 2026-11-02}
}

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