gamma(3) -- Linux man page
NAME
gamma, gammaf, gammal - (logarithm of the) gamma function
SYNOPSIS
#include <math.h>
double gamma(double x);
float gammaf(float x);
long double gammal(long double x);
DESCRIPTION
For the definition of the Gamma function, see
tgamma(3).
*BSD version
4.4BSD and FreeBSD libm have a
gamma()
function that computes the Gamma function, as one would expect.
glibc version
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.)
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(),
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.
CONFORMING TO
4.2BSD. Compatible with previous mistakes.
SEE ALSO
lgamma(3),
signgam(3),
tgamma(3)
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