1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
4 .\" Distributed under GPL
7 .\" Modified 2003-11-18, aeb: historical remarks
9 .TH GAMMA 3 2008-08-05 "GNU" "Linux Programmer's Manual"
11 gamma, gammaf, gammal \- (logarithm of the) gamma function
15 .BI "double gamma(double " x ");"
17 .BI "float gammaf(float " x ");"
19 .BI "long double gammal(long double " x ");"
24 Feature Test Macro Requirements for glibc (see
25 .BR feature_test_macros (7)):
31 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
36 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600
37 .\" Also seems to work: -std=c99 -D_XOPEN_SOURCE
41 These functions are deprecated: instead, use either the
45 functions, as appropriate.
47 For the definition of the Gamma function, see
50 The libm in 4.4BSD and some versions of FreeBSD had a
52 function that computes the Gamma function, as one would expect.
56 function that is equivalent to
58 and computes the natural logarithm of the Gamma function.
66 Because of historical variations in behavior across systems,
67 this function is not specified in any standard.
73 .RI ln(|Gamma(| x |)|),
76 in the external integer
78 In 4.3BSD the name was changed to
80 and the man page promises
83 "At some time in the future the name gamma will be rehabilitated
84 and used for the Gamma function"
87 This did indeed happen in 4.4BSD, where
89 computes the Gamma function (with no effect on
91 However, this came too late, and we now have
93 the "true gamma" function.
94 .\" The FreeBSD man page says about gamma() that it is like lgamma()
95 .\" except that is does not set signgam.
96 .\" Also, that 4.4BSD has a gamma() that computes the true gamma function.