src/base/math/copysign.c


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#include <u.h>
#include <base.h>

double
math·copysign(double x, double y)
{
	union {double f; uint64 i;} ux={x}, uy={y};
	ux.i &= -1ULL/2;
	ux.i |= uy.i & 1ULL<<63;

	return ux.f;
}