radix_rsqrt_approx_basecase, radix_rsqrt_approx
Synopsis
#include <flint/radix.h>void radix_rsqrt_approx_basecase(nn_ptr q, nn_srcptr a, slong an, slong n, const radix_t radix)sourceGiven (a, \mathit{an}) read as a fixed-point number a \in [B^{-2}, 1) with \mathit{an} fraction limbs (one of the top two limbs nonzero), set (q, n + 2) to an approximation of 1/\sqrt a \in (1, B] with n fraction limbs and two integral limbs, with absolute error less than 4 B^{-n}/\sqrt a. The range of a is wider than for radix_inv_approx so that inputs with an odd number of limbs can be handled, the scale factor B^{1/2} not being a limb shift.
Cite this page
The FLINT team, “radix_rsqrt_approx_basecase, radix_rsqrt_approx (radix.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/radix/radix_rsqrt_approx_basecase.html (generated 2026-10-20).
@misc{flint-doc-radix-radix-rsqrt-approx-basecase,
author = {{The FLINT team}},
title = {{radix\_rsqrt\_approx\_basecase, radix\_rsqrt\_approx (radix.h)}},
howpublished = {FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev},
year = {2026},
url = {https://flintlib.org/doc/radix/radix_rsqrt_approx_basecase.html},
note = {Generated 2026-10-20}
}