SIGNBIT(3) libc math functions SIGNBIT(3)NAMEsignbit - test sign of a real floating point number
SYNOPSIS
#include <math.h>
int signbit (X);
Compile with -std=c99; link with -lm.
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.
CONFORMING TO
C99. This function is defined in IEC 559 (and the appendix with recom‐
mended functions in IEEE 754/IEEE 854).
SEE ALSOcopysign(3)GNU 2002-08-10 SIGNBIT(3)