Originální popis anglicky:
gamma, gammaf, gammal - (logarithm of the) gamma function
Návod, kniha: libc math functions
#include <math.h>
double gamma(double x);
float gammaf(float x);
long double gammal(long double x);
Link with -lm.
For the definition of the Gamma function, see
tgamma(3).
4.4BSD and FreeBSD libm have a
gamma() function that computes the Gamma
function, as one would expect.
Glibc has a
gamma() function that is equivalent to
lgamma() and
computes the natural logarithm of the Gamma function. (This is for
compatibility reasons only. Don't use this function.)
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(), 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(), the "true gamma" function.
4.2BSD. Compatible with previous mistakes.
lgamma(3),
signgam(3),
tgamma(3)
