COPYSIGN(3) manual page
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copysign, copysignf, copysignl - copy
sign of a number
#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
The copysign(), copysignf(), and copysignl() 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.
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.
No errors occur.
The copysign(), copysignf(), and copysignl() functions
are thread-safe.
C99, POSIX.1-2001. This function is defined in
IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
On architectures where the floating-point formats are not IEEE 754
compliant, these functions may treat a negative zero as positive.
signbit(3)
This page is part of release 3.78 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 http://www.kernel.org/doc/man-pages/.
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