NAME
signbit() — floating-point sign-determination
SYNOPSIS
#include <math.h>
int signbit(
floating-type
x);
DESCRIPTION
The
signbit()
macro determines whether the sign of its argument value (which may
be a floating-point number, zero, infinity, or NaN) is negative.
The argument must be of floating type.
For HP Integrity servers, the argument
can be any floating type. For PA-RISC, the argument must be
either
double
or
float.
USAGE
To use the
signbit()
macro, compile either with the default
-Ae
option or with the
-Aa
and
-D_HPUX_SOURCE
options. Make sure your program includes
<math.h>.
Link in the math library by specifying
-lm
on the compiler or linker command line.
RETURN VALUE
The
signbit()
macro returns a nonzero value if and only if the sign of its argument
value is negative.
The macro raises no exceptions.
ERRORS
No errors are defined.
EXAMPLES
Take certain actions if
x
is negative zero:
#include <math.h>
/*...*/
double x;
/*...*/
if ( (x == 0.0) && signbit(x) ) {
/*...*/
}
STANDARDS CONFORMANCE
signbit()
: ISO/IEC C99 (including Annex F, ``IEC 60559 floating-point arithmetic'')
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