ref: f5c6a870bfb6d92f623aaa42bb60f074638e37fe
dir: /sys/src/cmd/python/Python/fmod.c/
/* Portable fmod(x, y) implementation for systems that don't have it */
#include "pyconfig.h"
#include "pyport.h"
#include <errno.h>
double
fmod(double x, double y)
{
double i, f;
if (y == 0.0) {
errno = EDOM;
return 0.0;
}
/* return f such that x = i*y + f for some integer i
such that |f| < |y| and f has the same sign as x */
i = floor(x/y);
f = x - i*y;
if ((x < 0.0) != (y < 0.0))
f = f-y;
return f;
}