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   gammal    ( 3 )

логарифм гамма-функции + C6328 ((logarithm of the) gamma function)

Имя (Name)

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

Синопсис (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(): _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


Описание (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.


Возвращаемое значение (Return value)

See lgamma(3).

Ошибки (Error)

See lgamma(3).

Атрибуты (Attributes)

For an explanation of the terms used in this section, see
       attributes(7).

┌───────────────────────┬───────────────┬────────────────────────┐ │Interface Attribute Value │ ├───────────────────────┼───────────────┼────────────────────────┤ │gamma(), gammaf(), │ Thread safety │ MT-Unsafe race:signgam │ │gammal() │ │ │ └───────────────────────┴───────────────┴────────────────────────┘


Стандарты (Conforming to)

Because of historical variations in behavior across systems, this
       function is not specified in any recent standard.  It was
       documented in SVID 2.

Примечание (Note)

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). However, this came too late, and we now have tgamma(3), the "true gamma" function.


Смотри также (See also)

lgamma(3), signgam(3), tgamma(3)