GAMMA(3M)                                               GAMMA(3M)

     NAME
          gamma - log gamma function

     SYNOPSIS
          #include <math.h>

          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 might be
          used to calculate Γ:

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

     DIAGNOSTICS
          A huge value is returned for negative integer arguments.

     BUGS
          There should be a positive indication of error.