NAME

       copysign, copysignf, copysignl - copy sign of a number

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);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       copysign(), copysignf(), copysignl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       These  functions return a value whose absolute value matches that of x, but whose sign bit
       matches that of y.

       For example, copysign(42.0, -1.0) and copysign(-42.0, -1.0) both return -42.0.

RETURN VALUE

       On success, these functions return a value whose magnitude is taken from x and whose  sign
       is taken from y.

       If x is a NaN, a NaN with the sign bit of y is returned.

ERRORS

       No errors occur.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │copysign(), copysignf(), copysignl()                           │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       C99,  POSIX.1-2001,  POSIX.1-2008.   This function is defined in IEC 559 (and the appendix
       with recommended functions in IEEE 754/IEEE 854).

NOTES

       On architectures where the floating-point  formats  are  not  IEEE  754  compliant,  these
       functions may treat a negative zero as positive.

SEE ALSO

       signbit(3)