FINITE(3)

NAME
finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl - BSD floating point classification functions

SYNOPSIS
#include <math.h>

int finite(double x);
int finitef(float x);
int finitel(long double x);

int isinf(double x);
int isinff(float x);
int isinfl(long double x);

int isnan(double x);
int isnanf(float x);
int isnanl(long double x);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

finite(), finitef(), finitel(): _BSD_SOURCE || _SVID_SOURCE
isinf(), isinff(), isinfl(): _BSD_SOURCE || _SVID_SOURCE
isnan(), isnanf(), isnanl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE

DESCRIPTION
The finite() functions return a non-zero value if x is neither infinite nor a "not-a-number" (NaN) value, and 0 otherwise. The isnan() functions return a non-zero value if x is a NaN value, and 0 otherwise. The isinf() functions return 1 if x is plus infinity, -1 is x is minus infinity, and 0 otherwise.

NOTES
Note that these functions are obsolete. C99 defines macros isfinite(), isinf() and isnan() (for all types) replacing them. Further note that the C99 isinf() has weaker guarantees on the return value. See fpclassify(3).

SEE ALSO
fpclassify(3)