finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl - BSD floating-point classification functions
#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(): /* 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
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.
For an explanation of the terms used in this section, see attributes(7). ┌────────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├────────────────────────────────┼───────────────┼─────────┤ │finite(), finitef(), finitel(), │ Thread safety │ MT-Safe │ │isinf(), isinff(), isinfl(), │ │ │ │isnan(), isnanf(), isnanl() │ │ │ └────────────────────────────────┴───────────────┴─────────┘
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).
This page is part of release 4.09 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/. 2016-03-15 FINITE(3)
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