NAME

gamma − log gamma function

SYNOPSIS

#include <math.h>
extern int signgam;

double gamma (x)
double x;

DESCRIPTION

Gamma returns ln|Γ(|x|)|. The sign of Γ(|x|) is returned in the external integer signgam. The following C program fragment might be used to calculate Γ:

y = gamma (x);
if (y > 88.0)
error ();
y = exp (y) ∗ signgam;

DIAGNOSTICS

For negative integer arguments, a huge value is returned, and errno is set to EDOM. 

May 16, 1980