gamma, gammaf, gammal - (logarithm of the) gamma function
#include <math.h>
[[deprecated]] double gamma(double x);
[[deprecated]] float gammaf(float x);
[[deprecated]] long double gammal(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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).
The libm in 4.4BSD and some versions of FreeBSD had a gamma() function that computes the Gamma function, as one would expect.
glibc has a gamma() function that is equivalent to lgamma(3) and computes the natural logarithm of the Gamma function.
See lgamma(3).