fpclassify

<html> <head> <title>fpclassify</title> <META NAME="KEYWORDS" CONTENT="fpclassify"> </head> <body BGCOLOR="#ffffff" LINK="#0000ff" VLINK="#0000ff" ALINK="#0000ff" TEXT="#000000"> <center> <h1>fpclassify</h1></center> <PRE> <A HREF="/man3/FPCLASSIFY">FPCLASSIFY(3)</A> Linux Programmer's Manual <A HREF="/man3/FPCLASSIFY">FPCLASSIFY(3)</A> NAME fpclassify, isfinite, isnormal, isnan, isinf - floating-point classifi- cation macros SYNOPSIS #include <math.h> int fpclassify(x); int isfinite(x); int isnormal(x); int isnan(x); int isinf(x); Link with -lm. Feature Test Macro Requirements for glibc (see <A HREF="/man7/feature_test_macros">feature_test_macros(7)</A>): fpclassify(), isfinite(), isnormal(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L isnan(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE isinf(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE DESCRIPTION Floating point numbers can have special values, such as infinite or NaN. With the macro fpclassify(x) you can find out what type x is. The macro takes any floating-point expression as argument. The result is one of the following values: FP_NAN x is "Not a Number". FP_INFINITE x is either positive infinity or negative infinity. FP_ZERO x is zero. FP_SUBNORMAL x is too small to be represented in normalized format. FP_NORMAL if nothing of the above is correct then it must be a nor- mal floating-point number. The other macros provide a short answer to some standard questions. isfinite(x) returns a nonzero value if (fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE) isnormal(x) returns a nonzero value if (fpclassify(x) == FP_NORMAL) isnan(x) returns a nonzero value if (fpclassify(x) == FP_NAN) isinf(x) returns 1 if x is positive infinity, and -1 if x is nega- tive infinity. ATTRIBUTES For an explanation of the terms used in this section, see at- <A HREF="/man7/tributes">tributes(7)</A>. +-----------------------------+---------------+---------+ |Interface | Attribute | Value | +-----------------------------+---------------+---------+ |fpclassify(), isfinite(), | Thread safety | MT-Safe | |isnormal(), isnan(), isinf() | | | +-----------------------------+---------------+---------+ CONFORMING TO POSIX.1-2001, POSIX.1-2008, C99. For isinf(), the standards merely say that the return value is nonzero if and only if the argument has an infinite value. NOTES In glibc 2.01 and earlier, isinf() returns a nonzero value (actually: 1) if x is positive infinity or negative infinity. (This is all that C99 requires.) SEE ALSO <A HREF="/man3/finite">finite(3)</A>, <A HREF="/man3/INFINITY">INFINITY(3)</A>, <A HREF="/man3/isgreater">isgreater(3)</A>, <A HREF="/man3/signbit">signbit(3)</A> COLOPHON This page is part of release 5.05 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/. 2017-09-15 <A HREF="/man3/FPCLASSIFY">FPCLASSIFY(3)</A></PRE> <center> <h6>Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2025 <a href="http://www.he.net">Hurricane Electric</a>. All Rights Reserved.</h6></center> </body> </html>

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