--- /dev/null
+## Copyright (C) 2007 R.G.H. Eschauzier <reschauzier@yahoo.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/>.
+
+## Adapted by Carnë Draug on 2011 <carandraug+dev@gmail.com>
+
+## This function is necessary for impinvar and invimpinvar of the signal package
+
+## Reverse the coefficients of a polynomial
+function p_out = polyrev (p_in)
+ p_out = p_in(end:-1:1);
+endfunction