// { dg-additional-options "-fmodules-ts" } | |
export module sqrt; | |
// { dg-module-cmi "sqrt" } | |
export constexpr unsigned sqrt (unsigned X, unsigned x = 1) | |
{ | |
// Newton-Raphson, not binary restoring | |
// x <= x - f(x)/f'(x) | |
// f(x) = x^2 - X | |
// f'(x) = 2x | |
// x <= x - (x^2 - X) / 2x | |
// x <= x - x/2 + X/2x | |
// x <= x/2 + X/2x | |
// x <= 1/2(x + X/x) | |
unsigned nx = (x + X/x) / 2; | |
if (nx != x) | |
nx = sqrt (X, nx); | |
return nx; | |
} |