FINITE(3) Linux Programmer's Manual FINITE(3)NAME
finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl
- BSD floating point classification functions
SYNOPSIS
#define _BSD_SOURCE
#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);
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.
NOTE
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 fpclas‐
sify(3).
AVAILABILITY
On a glibc system, these functions are declared by <math.h> when
_BSD_SOURCE or _SVID_SOURCE or _GNU_SOURCE is defined. The isnan()
functions will also be declared when _XOPEN_SOURCE is defined.
HISTORY
The finite() function occurs in 4.3BSD.
SEE ALSOfpclassify(3), feature_test_macros(7)
2004-10-31 FINITE(3)