NAME

fpclassify, isfinite, isinf, isnan, isnormal —

classify a floating-point number

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

int
fpclassify(real-floating x);

int
isfinite(real-floating x);

int
isinf(real-floating x);

int
isnan(real-floating x);

int
isnormal(real-floating x);

DESCRIPTION

The fpclassify() macro takes an argument of x and returns one of the following manifest constants.

FP_INFINITE: Indicates that x is an infinite number.
FP_NAN: Indicates that x is not a number (NaN).
FP_NORMAL: Indicates that x is a normalized number.
FP_SUBNORMAL: Indicates that x is a denormalized number.
FP_ZERO: Indicates that x is zero (0 or -0).

The isfinite() macro returns a non-zero value if and only if its argument has a finite (zero, subnormal, or normal) value. The isinf(), isnan(), and isnormal() macros return non-zero if and only if x is an infinity, NaN, or a non-zero normalized number, respectively.

The symbol isnanf() is provided as an alias to isnan() for compatibility, and its use is deprecated. Similarly, finite() and finitef() are deprecated versions of isfinite().

STANDARDS

The fpclassify(), isfinite(), isinf(), isnan(), and isnormal() macros conform to ISO/IEC 9899:1999 (“ISO C99”).

HISTORY

The fpclassify(), isfinite(), isinf(), isnan(), and isnormal() macros were added in FreeBSD 5.1. 3BSD introduced isinf() and isnan() functions, which accepted double arguments; these have been superseded by the macros described above.