155 lines
2.9 KiB
HTML
155 lines
2.9 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of INFINITY</TITLE>
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</HEAD><BODY>
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<H1>INFINITY</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL - floating-point constants
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#define _ISOC99_SOURCE</B> /* See <A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A>(7) */
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<B>#include <<A HREF="file:///usr/include/math.h">math.h</A>></B>
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<B>INFINITY</B>
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<B>NAN</B>
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<B>HUGE_VAL</B>
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<B>HUGE_VALF</B>
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<B>HUGE_VALL</B>
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The macro
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<B>INFINITY</B>
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expands to a
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<I>float</I>
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constant representing positive infinity.
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<P>
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The macro
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<B>NAN</B>
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expands to a
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<I>float</I>
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constant representing a quiet NaN
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(when supported).
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A
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<I>quiet</I>
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NaN is a NaN ("not-a-number") that does not raise exceptions
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when it is used in arithmetic.
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The opposite is a
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<I>signaling</I>
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NaN.
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See IEC 60559:1989.
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<P>
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The macros
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<B>HUGE_VAL</B>,
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<B>HUGE_VALF</B>,
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<B>HUGE_VALL</B>
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expand to constants of types
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<I>double</I>,
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<I>float</I>
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and
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<I>long double</I>,
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respectively,
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that represent a large positive value, possibly positive infinity.
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<A NAME="lbAE"> </A>
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<H2>CONFORMING TO</H2>
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C99.
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<A NAME="lbAF"> </A>
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<H2>AVAILABILITY</H2>
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On a glibc system, the macro
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<B>HUGE_VAL</B>
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is always available.
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Availability of the
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<B>NAN</B>
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macro can be tested using
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<B>#ifdef NAN</B>,
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and similarly for
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<B>INFINITY</B>,
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<B>HUGE_VALF</B>,
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<B>HUGE_VALL</B>.
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They will be defined by
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<I><<A HREF="file:///usr/include/math.h">math.h</A>></I>
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if
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<B>_ISOC99_SOURCE</B>
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or
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<B>_GNU_SOURCE</B>
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is defined, or
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<B>__STDC_VERSION__</B>
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is defined
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and has a value not less than 199901L.
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+fpclassify">fpclassify</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+math_error">math_error</A></B>(7)
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<A NAME="lbAH"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">CONFORMING TO</A><DD>
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<DT id="5"><A HREF="#lbAF">AVAILABILITY</A><DD>
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<DT id="6"><A HREF="#lbAG">SEE ALSO</A><DD>
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<DT id="7"><A HREF="#lbAH">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:46 GMT, March 31, 2021
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