FLINT3.7.0-dev
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radix_inv_approx_basecase, radix_inv_approx

Synopsis#include <flint/radix.h>
void radix_inv_approx_basecase(nn_ptr q, nn_srcptr a, slong an, slong n, const radix_t radix)source
void radix_inv_approx(nn_ptr q, nn_srcptr a, slong an, slong n, const radix_t radix)source

Given (a,an)(a, \mathit{an}) with aan−1≠0a_{an-1} \ne 0, read as a fixed-point number a∈[1/B,1)a \in [1/B, 1) with an\mathit{an} fraction limbs, set (q,n+2)(q, n + 2) to an approximation of 1/a∈(1,B]1/a \in (1, B] with nn fraction limbs and two integral limbs (the top one may be zero). The absolute error is less than 4B−n/a4 B^{-n}/a (relative error less than 4B−n4 B^{-n}). The general version uses Newton iteration from the basecase.

Cite this page

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