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);
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
finite(), finitef(), finitel():
/* Glibc since 2.19:
*/ _DEFAULT_SOURCE || /* Glibc versions <= 2.19:
*/ _BSD_SOURCE || _SVID_SOURCE
isinf():
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || /* Glibc since 2.19:
*/ _DEFAULT_SOURCE || /* Glibc versions <= 2.19:
*/ _BSD_SOURCE || _SVID_SOURCE
isinff(), isinfl():
/* Glibc since 2.19:
*/ _DEFAULT_SOURCE || /* Glibc versions <= 2.19:
*/ _BSD_SOURCE || _SVID_SOURCE
isnan():
_XOPEN_SOURCE || _ISOC99_SOURCE || /* Glibc since 2.19:
*/ _DEFAULT_SOURCE || /* Glibc versions <= 2.19:
*/ _BSD_SOURCE || _SVID_SOURCE
isnanf(), isnanl():
_XOPEN_SOURCE >= 600 || /* Glibc since 2.19:
*/ _DEFAULT_SOURCE || /* Glibc versions <= 2.19:
*/ _BSD_SOURCE || _SVID_SOURCE

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

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value

finite(), finitef(), finitel(),

isinf(), isinff(), isinfl(),

isnan(), isnanf(), isnanl()

Thread safety MT-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).

SEE ALSO

fpclassify(3)

COLOPHON

This page is part of release 4.07 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man−pages/.


  Copyright 2004 Andries Brouwer <aebcwi.nl>.

%%%LICENSE_START(VERBATIM)
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
%%%LICENSE_END