FINITE(3) Linux Programmer s Manual FINITE(3)

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

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 positive infinity, -1 if x is negative infinity, and 0 otherwise.

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 fpclas- sify(3).

SEE ALSO fpclassify(3)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

2008-08-05 FINITE(3)