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

**copysign**, **copysignf** - functions to manipulate signs

libm

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

The **copysign**() and **copysignf**() functions return a value whose absolute
value matches *x*, but whose sign bit is taken from *y*.

Upon 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*.

math(3), signbit(3)

The described functions conform to ISO/IEC 9899:1999 ("ISO C99").

Note that on implementations that represent a signed zero but do not
treat negative zero consistently in arithmetic operations, these func-
tions may regard the sign of zero as positive.
MirBSD #10-current February 9, 2014 1