FINITE

Section: Linux Programmer's Manual (3)
Updated: 2013-07-22
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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():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE;
or cc -std=c99

isinff(), isinfl():
_BSD_SOURCE || _SVID_SOURCE
isnan():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE;
or cc -std=c99
isnanf(), isnanl():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600

DESCRIPTION

The finite(), finitef(), and finitel() functions return a nonzero value if x is neither infinite nor a "not-a-number" (NaN) value, and 0 otherwise.

The isnan(), isnanf(), and isnanl() functions return a nonzero value if x is a NaN value, and 0 otherwise.

The isinf(), isinff(), and isinfl() functions return 1 if x is positive infinity, -1 if x is negative infinity, and 0 otherwise.

ATTRIBUTES

Multithreading (see pthreads(7))

The finite(), finitef(), finitel(), isinf(), isinff(), isinfl(), isnan(), isnanf(), and isnanl() functions are thread-safe.

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).

fpclassify(3)

COLOPHON

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Index

NAME
SYNOPSIS
DESCRIPTION
ATTRIBUTES
Multithreading (see pthreads(7))
NOTES
SEE ALSO
COLOPHON