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);

       Link with -lm.

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

       copysign(), copysignf(), copysignl():
           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

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 │
       └─────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       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)

COLOPHON

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