v7 man page for copysign

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

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():
	   _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
	       || /* Since glibc 2.19: */ _DEFAULT_SOURCE
	       || /* Glibc versions <= 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 |
       +-------------------------------------+---------------+---------+
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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GNU
								    2017-09-15							       COPYSIGN(3)