NAME

       PDL::GSLSF::PSI - PDL interface to GSL Special Functions

DESCRIPTION

       This is an interface to the Special Function package present in the GNU Scientific
       Library.

       Poly-Gamma Functions

       psi(m,x) := (d/dx)^m psi(0,x) = (d/dx)^{m+1} log(gamma(x))

SYNOPSIS

FUNCTIONS

   gsl_sf_psi
         Signature: (double x(); double [o]y(); double [o]e())

       Di-Gamma Function psi(x).

       gsl_sf_psi does not process bad values.  It will set the bad-value flag of all output
       piddles if the flag is set for any of the input piddles.

   gsl_sf_psi_1piy
         Signature: (double x(); double [o]y(); double [o]e())

       Di-Gamma Function Re[psi(1 + I y)]

       gsl_sf_psi_1piy does not process bad values.  It will set the bad-value flag of all output
       piddles if the flag is set for any of the input piddles.

   gsl_sf_psi_n
         Signature: (double x(); double [o]y(); double [o]e(); int n)

       Poly-Gamma Function psi^(n)(x)

       gsl_sf_psi_n does not process bad values.  It will set the bad-value flag of all output
       piddles if the flag is set for any of the input piddles.

AUTHOR

       This file copyright (C) 1999 Christian Pellegrin <chri@infis.univ.trieste.it> All rights
       reserved. There is no warranty. You are allowed to redistribute this software /
       documentation under certain conditions. For details, see the file COPYING in the PDL
       distribution. If this file is separated from the PDL distribution, the copyright notice
       should be included in the file.

       The GSL SF modules were written by G. Jungman.