224 lines
5.2 KiB
HTML
224 lines
5.2 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 GAMMA</TITLE>
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</HEAD><BODY>
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<H1>GAMMA</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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gamma, gammaf, gammal - (logarithm of the) gamma function
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/math.h">math.h</A>></B>
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<P>
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<B>double gamma(double </B><I>x</I><B>);</B>
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<BR>
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<B>float gammaf(float </B><I>x</I><B>);</B>
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<BR>
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<B>long double gammal(long double </B><I>x</I><B>);</B>
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<P>
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Link with <I>-lm</I>.
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>gamma</B>():
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<DL COMPACT><DT id="1"><DD>
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_XOPEN_SOURCE
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<BR> || /* Since glibc 2.19: */ _DEFAULT_SOURCE
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<BR> || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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</DL>
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<B>gammaf</B>(),
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<B>gammal</B>():
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<DL COMPACT><DT id="2"><DD>
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_XOPEN_SOURCE >= 600 || (_XOPEN_SOURCE && _ISOC99_SOURCE)
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<BR> || /* Since glibc 2.19: */ _DEFAULT_SOURCE
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<BR> || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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These functions are deprecated: instead, use either the
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<B><A HREF="/cgi-bin/man/man2html?3+tgamma">tgamma</A></B>(3)
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or the
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<B><A HREF="/cgi-bin/man/man2html?3+lgamma">lgamma</A></B>(3)
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functions, as appropriate.
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<P>
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For the definition of the Gamma function, see
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<B><A HREF="/cgi-bin/man/man2html?3+tgamma">tgamma</A></B>(3).
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<A NAME="lbAE"> </A>
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<H3>*BSD version</H3>
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The libm in 4.4BSD and some versions of FreeBSD had a
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<B>gamma</B>()
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function that computes the Gamma function, as one would expect.
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<A NAME="lbAF"> </A>
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<H3>glibc version</H3>
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Glibc has a
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<B>gamma</B>()
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function that is equivalent to
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<B><A HREF="/cgi-bin/man/man2html?3+lgamma">lgamma</A></B>(3)
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and computes the natural logarithm of the Gamma function.
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<A NAME="lbAG"> </A>
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<H2>RETURN VALUE</H2>
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See
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<B><A HREF="/cgi-bin/man/man2html?3+lgamma">lgamma</A></B>(3).
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<A NAME="lbAH"> </A>
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<H2>ERRORS</H2>
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See
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<B><A HREF="/cgi-bin/man/man2html?3+lgamma">lgamma</A></B>(3).
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<A NAME="lbAI"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>gamma</B>(),
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<B>gammaf</B>(),
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<B>gammal</B>()
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</TD><TD>Thread safety</TD><TD>MT-Unsafe race:signgam<BR></TD></TR>
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</TABLE>
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<A NAME="lbAJ"> </A>
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<H2>CONFORMING TO</H2>
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Because of historical variations in behavior across systems,
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this function is not specified in any recent standard.
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It was documented in SVID 2.
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<A NAME="lbAK"> </A>
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<H2>NOTES</H2>
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<A NAME="lbAL"> </A>
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<H3>History</H3>
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4.2BSD had a
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<B>gamma</B>()
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that computed
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ln(|Gamma(|<I>x</I>|)|),
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leaving the sign of
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Gamma(|<I>x</I>|)
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in the external integer
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<I>signgam</I>.
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In 4.3BSD the name was changed to
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<B><A HREF="/cgi-bin/man/man2html?3+lgamma">lgamma</A></B>(3),
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and the man page promises
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<P>
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"At some time in the future the name gamma will be rehabilitated
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and used for the Gamma function"
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<P>
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This did indeed happen in 4.4BSD, where
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<B>gamma</B>()
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computes the Gamma function (with no effect on
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<I>signgam</I>).
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However, this came too late, and we now have
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<B><A HREF="/cgi-bin/man/man2html?3+tgamma">tgamma</A></B>(3),
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the "true gamma" function.
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<A NAME="lbAM"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+lgamma">lgamma</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+signgam">signgam</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+tgamma">tgamma</A></B>(3)
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<A NAME="lbAN"> </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="3"><A HREF="#lbAB">NAME</A><DD>
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<DT id="4"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="5"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DL>
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<DT id="6"><A HREF="#lbAE">*BSD version</A><DD>
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<DT id="7"><A HREF="#lbAF">glibc version</A><DD>
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</DL>
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<DT id="8"><A HREF="#lbAG">RETURN VALUE</A><DD>
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<DT id="9"><A HREF="#lbAH">ERRORS</A><DD>
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<DT id="10"><A HREF="#lbAI">ATTRIBUTES</A><DD>
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<DT id="11"><A HREF="#lbAJ">CONFORMING TO</A><DD>
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<DT id="12"><A HREF="#lbAK">NOTES</A><DD>
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<DL>
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<DT id="13"><A HREF="#lbAL">History</A><DD>
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</DL>
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<DT id="14"><A HREF="#lbAM">SEE ALSO</A><DD>
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<DT id="15"><A HREF="#lbAN">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: 00:05:44 GMT, March 31, 2021
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