--- /dev/null
+## Copyright (C) 2010 Lukas F. Reichlin
+##
+## 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 -*-
+## Vertical concatenation of quaternions. Used by Octave for "[q1; q2]".
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: May 2010
+## Version: 0.1
+
+function q = vertcat (varargin)
+
+ tmp = cellfun (@quaternion, varargin); # uniformoutput = true !
+
+ w = vertcat (tmp.w);
+ x = vertcat (tmp.x);
+ y = vertcat (tmp.y);
+ z = vertcat (tmp.z);
+
+ q = quaternion (w, x, y, z);
+
+endfunction