--- /dev/null
+## Copyright (C) 1996, 1998, 2000, 2003, 2004, 2005, 2006, 2007 Auburn University
+## Copyright (C) 2012 Lukas F. Reichlin <lukas.reichlin@gmail.com>
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {[@var{zer}, @var{pol}, @var{k}] =} tf2zp (@var{num}, @var{den})
+## Converts transfer functions to poles-and-zero representations.
+##
+## Returns the zeros and poles of the system defined
+## by @var{num}/@var{den}.
+## @var{k} is a gain associated with the system zeros.
+## @end deftypefn
+
+## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu>
+
+function [z, p, k] = tf2zp (varargin)
+
+ if (nargin == 0)
+ print_usage ();
+ endif
+
+ [z, p, k] = zpkdata (tf (varargin{:}), "vector");
+
+endfunction