shithub: npe

ref: ebf07866d4c0be18dd2a7dd623e9458220e5ebb1
dir: /libnpe/log2.c/

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#include <math.h>

#define ln2o1 1.4426950408889634073599
#define huge 1.79769313486231e+308

double
log2(double x)
{
	if(x == 0)
		return -huge;
	if(x < 0 || isNaN(x))
		return NaN();

	return log(x)*ln2o1;
}