1 ## Copyright (C) 2009 Lukas F. Reichlin
3 ## This file is part of LTI Syncope.
5 ## LTI Syncope is free software: you can redistribute it and/or modify
6 ## it under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation, either version 3 of the License, or
8 ## (at your option) any later version.
10 ## LTI Syncope is distributed in the hope that it will be useful,
11 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 ## GNU General Public License for more details.
15 ## You should have received a copy of the GNU General Public License
16 ## along with LTI Syncope. If not, see <http://www.gnu.org/licenses/>.
19 ## Binary subtraction of LTI objects. If necessary, object conversion
20 ## is done by sys_group. Used by Octave for "sys1 - sys2".
22 ## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
23 ## Created: September 2009
26 function sys = minus (sys1, sys2)
28 if (nargin != 2) # prevent sys = minus (sys1, sys2, sys3, ...)
29 error ("lti: minus: this is a binary operator");
32 [p1, m1] = size (sys1);
33 [p2, m2] = size (sys2);
35 if (p1 != p2 || m1 != m2)
36 error ("lti: minus: system dimensions incompatible: (%dx%d) - (%dx%d)",
40 sys = __sys_group__ (sys1, sys2);
42 in_scl = [eye(m1); eye(m2)];
43 out_scl = [eye(p1), -eye(p2)];
45 sys = out_scl * sys * in_scl;