◆ refine_rsqrt()

IEEEValue boost::simd::refine_rsqrt ( IEEEValue const &  x,
IEEEValue const &  est 

This function object performs a Newton-Raphson step to improve precision of rsqrt estimate.

This function can be used in conjunction with raw_(rsqrt) to add more precision to the estimates if their default precision is not enough.

Header <boost/simd/function/refine_rsqrt.hpp>
auto r = refine_rsqrt(x, est);

is similar to

auto r = fma( fnms(x, sqr(est), 1), est/2, est);
See also