--- a
+++ b/inst/@gf/plus.m
@@ -0,0 +1,27 @@
+## Copyright (C) 2011 David Bateman
+##
+## 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 2 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} {} plus (@var{a}, @var{b})
+## Binary addition operator over a Galois field.
+## @end deftypefn
+
+function y = plus (a, b)
+  [a, b] = promote_and_check (a, b);
+  y = gf (bitxor (a._x, b._x), a._m, a._prim_poly);
+endfunction
+
+%!assert(gf(0:7,3)+gf(0:7,3),gf(zeros(1,8),3))
+