1.12 copysign, copysignf—sign of y, magnitude of x

Synopsis

     #include <math.h>
     double copysign (double x, double y);
     float copysignf (float x, float y);
     

Description
copysign constructs a number with the magnitude (absolute value) of its first argument, x, and the sign of its second argument, y.

copysignf does the same thing; the two functions differ only in the type of their arguments and result.

Returns
copysign returns a double with the magnitude of x and the sign of y. copysignf returns a float with the magnitude of x and the sign of y.

Portability
copysign is not required by either ANSI C or the System V Interface Definition (Issue 2).