GAMMA(3) libc math functions GAMMA(3)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);
Link with -lm.
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 com‐
putes the natural logarithm of the Gamma function. (This is for com‐
patibility 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 ALSOlgamma(3), signgam(3), tgamma(3)GNU 2002-08-10 GAMMA(3)
