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**NAME**

finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl - BSD floating- point classification functions

**SYNOPSIS**

#include<math.h>intfinite(doublex);intfinitef(floatx);intfinitel(longdoublex);intisinf(doublex);intisinff(floatx);intisinfl(longdoublex);intisnan(doublex);intisnanf(floatx);intisnanl(longdoublex);Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):finite(),finitef(),finitel(): _BSD_SOURCE || _SVID_SOURCEisinf(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; orcc-std=c99isinff(),isinfl(): _BSD_SOURCE || _SVID_SOURCEisnan(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE; orcc-std=c99isnanf(),isnanl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600

**DESCRIPTION**

Thefinite() functions return a nonzero value ifxis neither infinite nor a "not-a- number" (NaN) value, and 0 otherwise. Theisnan() functions return a nonzero value ifxis a NaN value, and 0 otherwise. Theisinf() functions return 1 ifxis positive infinity, -1 ifxis negative infinity, and 0 otherwise.

**NOTES**

Note that these functions are obsolete. C99 defines macrosisfinite(),isinf(), andisnan() (for all types) replacing them. Further note that the C99isinf() has weaker guarantees on the return value. Seefpclassify(3).

**SEE** **ALSO**

fpclassify(3)

**COLOPHON**

This page is part of release 3.35 of the Linuxman-pagesproject. A description of the project, and information about reporting bugs, can be found at http://man7.org/linux/man- pages/. 2008-08-05 FINITE(3)