# Seth Woolley's Man Viewer

## finite(3) - finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl - BSD floating point classification functions - man 3 finite

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```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(3,n) x is  neither  infinite
nor a "not-a-number" (NaN) value, and 0 otherwise.

The  isnan functions return a non-zero value if(3,n) x is a NaN value, and 0
otherwise.

The isinf functions return 1 if(3,n) 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(1,8) BSD 4.3.

SEE ALSO
fpclassify(3)

2004-10-31                         FINITE(3)
```