gammal(3)

1GAMMA(3)                   Linux Programmer's Manual                  GAMMA(3)
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NAME

6       gamma, gammaf, gammal - (logarithm of the) gamma function
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SYNOPSIS

9       #include <math.h>
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11       double gamma(double x);
12       float gammaf(float x);
13       long double gammal(long double x);
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15       Link with -lm.
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       gamma():
20           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
21       gammaf(), gammal():
22           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
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DESCRIPTION

25       These  functions  are  deprecated: instead, use either the tgamma(3) or
26       the lgamma(3) functions, as appropriate.
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28       For the definition of the Gamma function, see tgamma(3).
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30   *BSD version
31       The libm in 4.4BSD and some versions of FreeBSD had a gamma()  function
32       that computes the Gamma function, as one would expect.
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34   glibc version
35       Glibc  has  a gamma() function that is equivalent to lgamma(3) and com‐
36       putes the natural logarithm of the Gamma function.
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RETURN VALUE

39       See lgamma(3).
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ERRORS

42       See lgamma(3).
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CONFORMING TO

45       Because of historical variations in behavior across systems, this func‐
46       tion is not specified in any standard.
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NOTES

49   History
50       4.2BSD  had  a gamma() that computed ln(|Gamma(|x|)|), leaving the sign
51       of Gamma(|x|) in the external integer signgam.  In 4.3BSD the name  was
52       changed to lgamma(3), and the man page promises
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54           "At  some  time  in the future the name gamma will be rehabilitated
55           and used for the Gamma function"
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57       This did indeed happen in 4.4BSD,  where  gamma()  computes  the  Gamma
58       function (with no effect on signgam).  However, this came too late, and
59       we now have tgamma(3), the "true gamma" function.
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COLOPHON

65       This page is part of release 3.53 of the Linux  man-pages  project.   A
66       description  of  the project, and information about reporting bugs, can
67       be found at http://www.kernel.org/doc/man-pages/.
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71GNU                               2008-08-05                          GAMMA(3)