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 non-zero 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
signbit(-0.0)
will return a non-zero value.
NaNs and infinities have a sign bit.
RETURN VALUE
The
signbit()
macro returns non-zero 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).
This page is part of release 3.14 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/.
