GAMMA(S)                 XENIX System V                  GAMMA(S)



     Name
          gamma - Performs log gamma function.

     Syntax
          #include <math.h>
          extern int signgam;

          double gamma (x)
          double x;

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

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

          where LN_MAXDOUBLE is the least value that causes exp(S) to
          return a range error and is defined in the <values.h> header
          file.

     Diagnostics
          For negative integer arguments, a HUGE value is returned and
          errno is set to EDOM.  A message indicating SING error is
          printed on the standard error output.

          If the correct value would overflow, gamma returns a HUGE
          value and errno is set to ERANGE.

          These error-handling procedures may be changed with the
          matherr(S) function.

     See Also
          exp(S), matherr(S)

     Notes
          These routines must be linked by using the -lm linker
          option.















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