logb.c\math\src - musl - musl - an implementation of the standard library for Linux-based systems

#include "libm.h"
/*
special cases:
	logb(+-0) = -inf, and raise divbyzero
	logb(+-inf) = +inf
	logb(nan) = nan
*/
double logb(double x)
{
	if (!isfinite(x))
		return x * x;
	if (x == 0)
		return -1/(x+0);
	return ilogb(x);
}