Originální popis anglicky:
finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl - BSD
floating point classification functions
Návod, kniha: Linux Programmer's Manual
#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);
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 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).
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.
The
finite function occurs in BSD 4.3.
fpclassify(3)
