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finite(3) — Linux manual page

finite(3)                Library Functions Manualfinite(3)

NAME        top

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

LIBRARY        top

       Math library (libm,-lm)

SYNOPSIS        top

#include <math.h>int finite(doublex);int finitef(floatx);int finitel(long doublex);int isinf(doublex);int isinff(floatx);int isinfl(long doublex);int isnan(doublex);int isnanf(floatx);int isnanl(long doublex);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):finite(),finitef(),finitel():           /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEisinf():           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE               || /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEisinff(),isinfl():           /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEisnan():           _XOPEN_SOURCE || _ISOC99_SOURCE               || /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEisnanf(),isnanl():           _XOPEN_SOURCE >= 600               || /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION        top

       Thefinite(),finitef(), andfinitel() functions return a nonzero       value ifx is neither infinite nor a "not-a-number" (NaN) value,       and 0 otherwise.       Theisnan(),isnanf(), andisnanl() functions return a nonzero       value ifx is a NaN value, and 0 otherwise.       Theisinf(),isinff(), andisinfl() functions return 1 ifx is       positive infinity, -1 ifx is negative infinity, and 0 otherwise.

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │finite(),finitef(),finitel(),      │ Thread safety │ MT-Safe │       │isinf(),isinff(),isinfl(),         │               │         │       │isnan(),isnanf(),isnanl()          │               │         │       └──────────────────────────────────────┴───────────────┴─────────┘

NOTES        top

       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        top

fpclassify(3)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17finite(3)

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