SIGNBIT(3) BSD Library Functions Manual SIGNBIT(3)NAME
signbit -- determine whether a floating-point number's sign is negative
LIBRARY
Math Library (libm, -lm)
SYNOPSIS
#include <math.h>
int
signbit(real-floating x);
DESCRIPTION
The signbit() macro takes an argument of x and returns non-zero if the value of its sign is negative, otherwise 0.
SEE ALSO fpclassify(3), math(3)STANDARDS
The signbit() macro conforms to ISO/IEC 9899:1999 (``ISO C99'').
HISTORY
The signbit() macro was added in FreeBSD 5.1.
BSD July 18, 2004 BSD
Check Out this Related Man Page
SIGNBIT(3) Linux Programmer's Manual SIGNBIT(3)NAME
signbit - test sign of a real floating-point number
SYNOPSIS
#include <math.h>
int signbit(x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
signbit(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
DESCRIPTION
signbit() is a generic macro which can work on all real floating-point types. It returns a nonzero value if the value of x has its sign
bit set.
This is not the same as x < 0.0, because IEEE 754 floating point allows zero to be signed. The comparison -0.0 < 0.0 is false, but sign-
bit(-0.0) will return a nonzero value.
NaNs and infinities have a sign bit.
RETURN VALUE
The signbit() macro returns nonzero if the sign of x is negative; otherwise it returns zero.
ERRORS
No errors occur.
CONFORMING TO
C99, POSIX.1-2001. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).
SEE ALSO copysign(3)COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2008-08-05 SIGNBIT(3)
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