NAME

copysign, copysignf, copysignl — functions to manipulate signs

LIBRARY

Math Library (libm, -lm)

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

RETURN VALUES

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.

SEE ALSO

math(3), signbit(3)

STANDARDS

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

CAVEATS

Note 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.