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

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────────────────────────────────────────────────────┬───────────────┬────────────────────────┐
       │ Interface                                                    │ Attribute     │ Value                  │
       ├──────────────────────────────────────────────────────────────┼───────────────┼────────────────────────┤
       │ gamma(), gammaf(), gammal()                                  │ Thread safety │ MT-Unsafe race:signgam │
       └──────────────────────────────────────────────────────────────┴───────────────┴────────────────────────┘

       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).

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

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

       See lgamma(3).

       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), 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.

       Math library (libm, -lm)

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

       See lgamma(3).

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

Linux man-pages 6.9.1                              2024-05-02                                           gamma(3)

       None.

#include<math.h>[[deprecated]]doublegamma(doublex);[[deprecated]]floatgammaf(floatx);[[deprecated]]longdoublegammal(longdoublex);

   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