1 ## Copyright (C) 2010, 2011 Lukas F. Reichlin
3 ## This program is free software: you can redistribute it and/or modify
4 ## it under the terms of the GNU General Public License as published by
5 ## the Free Software Foundation, either version 3 of the License, or
6 ## (at your option) any later version.
8 ## This program is distributed in the hope that it will be useful,
9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 ## GNU General Public License for more details.
13 ## You should have received a copy of the GNU General Public License
14 ## along with this program. If not, see <http://www.gnu.org/licenses/>.
17 ## Matrix power operator of quaternions. Used by Octave for "q^x".
19 ## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
23 function q = mpower (a, b)
28 error ("quaternion: mpower: quaternion matrix must be square");
31 if (r == 1 && c == 1) # a scalar, b?
32 q = a .^ b; # b could be a quaternion
33 elseif (is_real_array (b) && isscalar (b) && fix (b) == b)
40 q = eye (r); # alternative: q = quaternion (eye (r))
46 q *= a; # improvement?: q^8 = ((q^2)^2)^2, q^9 = (((q^2)^2)^2)*q
49 error ("quaternion: mpower: case not implemented yet");
50 q = expm (logm (a) * b); # don't know whether this formula is correct