FLINT3.7.0-dev
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gr_doublefac, gr_doublefac_ui

Synopsis#include <flint/gr_special.h>
int gr_doublefac(gr_ptr res, gr_srcptr x, gr_ctx_t ctx)source
int gr_doublefac_ui(gr_ptr res, ulong x, gr_ctx_t ctx)source

Set res to the double factorial x!! = x (x - 2) (x - 4) \cdots, ending at 1 or 2.

Cite this page

The FLINT team, “gr_doublefac, gr_doublefac_ui (gr_special.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/gr_special/gr_doublefac.html (generated 2026-10-20).