@(#)gamma.3 6.1 (Berkeley) 05/15/85

.AT 3 gamma - log gamma function

 #include <math.h> 

 double gamma(x)  double x; 

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

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

A huge value is returned for negative integer arguments. There should be a positive indication of error.