redhat man page for copysign

COPYSIGN(3)						     Linux Programmer's Manual						       COPYSIGN(3)

NAME
       copysign, copysignf, copysignl - copy sign of a number

SYNOPSIS
       #include <math.h>

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

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

SEE ALSO
       signbit(3)

GNU
								    2002-08-10							       COPYSIGN(3)