Updated: 2021/Apr/14

COPYSIGN(3) Library Functions Manual COPYSIGN(3)NAMEcopysign,copysignf,copysignl- functions to manipulate signsLIBRARYMath Library (libm, -lm)SYNOPSIS#include<math.h>doublecopysign(double x, double y); floatcopysignf(float x, float y); long doublecopysignl(long double x, long double y);#include<tgmath.h>real-floatingcopysign(real-floating x, real-floating y);DESCRIPTIONThecopysign(),copysignf(), andcopysignl() functions return a value whose absolute value matches x, but whose sign bit is taken from y.RETURNVALUESUpon successful completion, all three functions return a value with the magnitude of x and the sign of y. If x is NaN , the functions return a NaN with the sign of y.SEEALSOmath(3), signbit(3)STANDARDSThe described functions conform to ISO/IEC 9899:1999 ("ISO C99").CAVEATSNote that on implementations that represent a signed zero but do not treat negative zero consistently in arithmetic operations, these functions may regard the sign of zero as positive. NetBSD 9.99 September 28, 2017 NetBSD 9.99