1 ## Copyright (C) 2009, 2011 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 addition of LTI objects. If necessary, object conversion
20 ## is done by sys_group. Used by Octave for "sys1 + sys2".
21 ## Operation is also known as "parallel connection".
23 ## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
24 ## Created: September 2009
27 function sys = plus (sys1, sys2)
29 if (nargin != 2) # prevent sys = plus (sys1, sys2, sys3, ...)
30 error ("lti: plus: this is a binary operator");
33 [p1, m1] = size (sys1);
34 [p2, m2] = size (sys2);
36 if (p1 != p2 || m1 != m2)
37 error ("lti: plus: system dimensions incompatible: (%dx%d) + (%dx%d)",
41 sys = __sys_group__ (sys1, sys2);
43 in_scl = [eye(m1); eye(m2)];
44 out_scl = [eye(p1), eye(p2)];
46 sys = out_scl * sys * in_scl;
51 ## Parallel inter-connection of two systems in state-space form
52 ## Test from SLICOT AB05PD
54 %! A1 = [ 1.0 0.0 -1.0
61 %! C1 = [ 3.0 -2.0 1.0
71 %! B2 = [ 0.0 -1.0 0.0
80 %! sys1 = ss (A1, B1, C1, D1);
81 %! sys2 = ss (A2, B2, C2, D2);
83 %! [A, B, C, D] = ssdata (sys);
86 %! Ae = [ 1.0000 0.0000 -1.0000 0.0000 0.0000 0.0000
87 %! 0.0000 -1.0000 1.0000 0.0000 0.0000 0.0000
88 %! 1.0000 1.0000 2.0000 0.0000 0.0000 0.0000
89 %! 0.0000 0.0000 0.0000 -3.0000 0.0000 0.0000
90 %! 0.0000 0.0000 0.0000 1.0000 0.0000 1.0000
91 %! 0.0000 0.0000 0.0000 0.0000 -1.0000 2.0000 ];
93 %! Be = [ 1.0000 2.0000
100 %! Ce = [ 3.0000 -2.0000 1.0000 1.0000 1.0000 0.0000
101 %! 0.0000 1.0000 0.0000 1.0000 1.0000 -1.0000 ];
103 %! De = [ 2.0000 1.0000
106 %! Me = [Ae, Be; Ce, De];
108 %!assert (M, Me, 1e-4);