copysign, copysignf, copysignl – copy sign of a number

USAGE
       #include <math.h>

       double copysign(double x, double y);
       float copysignf(float x, float y);
       long double copysignl(long double x, long double y);

       Link with -lm.

DESCRIPTION
       The  copysign()  functions  return a value whose absolute value matches
       that of x, but whose sign matches that of y.  If x is a NaN, then a NaN
       with the sign of y is returned.

NOTES
       The copysign() functions may treat a negative zero as positive.

CONFORMING TO
       C99,  4.3BSD.   This  function  is defined in IEC 559 (and the appendix
       with recommended functions in IEEE 754/IEEE 854).

SEE ALSO
       signbit(3)