gamma(3) - Linux manual page (original) (raw)
gamma(3) Library Functions Manual gamma(3)
NAME top
gamma, gammaf, gammal - (logarithm of the) gamma function
LIBRARY top
Math library (_libm_, _-lm_)
SYNOPSIS top
**#include <math.h>**
**[[deprecated]] double gamma(double** _x_**);**
**[[deprecated]] float gammaf(float** _x_**);**
**[[deprecated]] long double gammal(long double** _x_**);**
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
**gamma**():
_XOPEN_SOURCE
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
**gammaf**(), **gammal**():
_XOPEN_SOURCE >= 600 || (_XOPEN_SOURCE && _ISOC99_SOURCE)
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION top
These functions are deprecated: instead, use either the [tgamma(3)](../man3/tgamma.3.html)
or the [lgamma(3)](../man3/lgamma.3.html) functions, as appropriate.
For the definition of the Gamma function, see [tgamma(3)](../man3/tgamma.3.html).
*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 top
See [lgamma(3)](../man3/lgamma.3.html).
ERRORS top
See [lgamma(3)](../man3/lgamma.3.html).
ATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌───────────────────────┬───────────────┬────────────────────────┐
│ **Interface** │ **Attribute** │ **Value** │
├───────────────────────┼───────────────┼────────────────────────┤
│ **gamma**(), **gammaf**(), │ Thread safety │ MT-Unsafe race:signgam │
│ **gammal**() │ │ │
└───────────────────────┴───────────────┴────────────────────────┘
STANDARDS top
None.
HISTORY top
SVID 2.
Because of historical variations in behavior across systems, this
function is not specified in any recent standard.
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)](../man3/lgamma.3.html), 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_). However, this came too
late, and we now have [tgamma(3)](../man3/tgamma.3.html), the "true gamma" function.
SEE ALSO top
[lgamma(3)](../man3/lgamma.3.html), [signgam(3)](../man3/signgam.3.html), [tgamma(3)](../man3/tgamma.3.html)
COLOPHON top
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Linux man-pages 6.10 2024-07-23 gamma(3)
Pages that refer to this page:tgamma(3)