Because of historical variations in behavior across systems,
this function is not specified in any standard.
NOTES
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.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
