fpclassify

NAME

fpclassify, isfinite, isnormal, isnan - floating-point classification macros

SYNOPSIS

#include <math.h>

int fpclassify(x);

int isfinite(x);

int isnormal(x);

int isnan(x);

int isinf(x);

DESCRIPTION

Floating point numbers can have special values, such as infinite or NaN. With the macro fpclassify(x) you can find out what type x is. The macro takes any floating-point expression as argument. The result takes one of the following values:

FP_NAN: x is "Not a Number".
FP_INFINITE: x is either plus or minus infinity.
FP_ZERO: x is zero.
FP_SUBNORMAL: x is too small to be represented in normalized format.
FP_NORMAL: if nothing of the above is correct that it must be a normal floating-point number.

The other macros provide a short answer to some standard questions.

isfinite(x): (fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
isnormal(x): (fpclassify(x) == FP_NORMAL)
isnan(x): (fpclassify(x) == FP_NAN)
isinf(x): (fpclassify(x) == FP_INFINITE)

NOTE

CONFORMING TO

C99