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



NAME
       gamma, gammaf, gammal - (logarithm of the) gamma function

SYNOPSIS
       #include <math.h>

       double gamma(double x);
       float gammaf(float x);
       long double gammal(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       gamma(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
       gammaf(), gammal(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600

DESCRIPTION
       These functions are deprecated: instead, use either the tgamma(3) or the lgamma(3) functions, as appropriate.

       For the definition of the Gamma function, see tgamma(3).

   *BSD version
       The libm in 4.4BSD and some versions of FreeBSD had a gamma() function that computes the Gamma function, as one
       would expect.

   glibc version
       Glibc has a gamma() function that is equivalent to lgamma(3) and computes the natural logarithm  of  the  Gamma
       function.

RETURN VALUE
       See lgamma(3).

ERRORS
       See lgamma(3).

CONFORMING TO
       Because of historical variations in behavior across systems, this function is not specified in any standard.

NOTES
   History
       4.2BSD  had  a  gamma()  that computed ln(|Gamma(|x|)|), leaving the sign of Gamma(|x|) in the external integer
       signgam.  In 4.3BSD the name was changed to lgamma(3), and the man page promises

           "At some time in the future the name gamma will be rehabilitated and used for the Gamma function"

       This did indeed happen in 4.4BSD, where gamma() computes the Gamma function (with no effect on signgam).   How-
       ever, this came too late, and we now have tgamma(3), the "true gamma" function.

SEE ALSO
       lgamma(3), signgam(3), tgamma(3)

COLOPHON
       This  page  is part of release 3.22 of the Linux man-pages project.  A description of the project, and informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                               2008-08-05                          GAMMA(3)