NAME
fpclassify() — floating-point operand classification macro
SYNOPSIS
#include <math.h>
int fpclassify(
floating-type
x);
DESCRIPTION
The
fpclassify()
macro classifies its argument value as NaN, infinite, normalized,
denormalized, or zero.
The
fpclassify()
macro can be used with either
double
or
float
arguments, and classifies the argument based on its type.
The ISO/ANSI C committee has approved the
fpclassify()
macro for inclusion in the forthcoming C9X draft standard. The
fpclassify()
macro implements the
class()
function recommended by the IEEE-754 standard for floating-point
arithmetic.
To use the
fpclassify()
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.
The
fpclassify()
macro, used in conjunction with the
signbit()
macro, replaces the
fpclassify()
and
fpclassifyf()
functions, which are obsolete and are no longer supported.
RETURN VALUE
The
fpclassify()
macro returns the value of the number classification macro appropriate
to the type and value of its argument.
The value returned is one of the following macros,
which are defined in
<math.h>:
FP_NORMAL Normalized
FP_ZERO Zero
FP_INFINITE Infinity
FP_SUBNORMAL Denormalized
FP_NAN NaN
Every possible argument value falls into one of these categories,
so these functions never result in an error.
ERRORS
No errors are defined.
EXAMPLE
Take certain actions if
x
is either a denormalized
float
value or zero:
#include <math.h>
/*...*/
int class;
float x;
/*...*/
class = fpclassify(x);
if ( (class == FP_SUBNORMAL) || (class == FP_ZERO) ) {
/*...*/
}
