copysign(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       copysign, copysignf, copysignl - copy sign of a number

SYNOPSIS         top

       #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():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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         top

       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         top

       No errors occur.

ATTRIBUTES         top

       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         top

       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         top

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

SEE ALSO         top

       signbit(3)

COLOPHON         top

       This page is part of release 5.12 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                            2021-03-22                    COPYSIGN(3)

Pages that refer to this page: signbit(3)