SIGNBIT(3) NEWLIB SIGNBIT(3)NAME
1.51 `signbit'-Does floating-point number have negative sign?
SYNOPSIS
#include <math.h>
int signbit(real-floating X);
DESCRIPTION
The `signbit' macro determines whether the sign of its argument value
is negative. The macro reports the sign of all values, including
infinities, zeros, and NaNs. If zero is unsigned, it is treated as
positive. As shown in the synopsis, the argument is "real-floating,"
meaning that any of the real floating-point types (float, double, etc.)
may be given to it.
Note that because of the possibilities of signed 0 and NaNs, the
expression "X < 0.0" does not give the same result as `signbit' in all
cases.
RETURNS
The `signbit' macro returns a nonzero value if and only if the sign of
its argument value is negative.
PORTABILITY
C99, POSIX.
SEE ALSOsignbit is part of the library. The full documentation for is main‐
tained as a Texinfo manual. If info and are properly installed at your
site, the command
info
will give you access to the complete manual.
NEWLIB April 2010 SIGNBIT(3)
