copysignf

       #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 com-
       pliant, these functions may treat a negative zero as positive.

SEE ALSO
       signbit(3)

COLOPHON
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