1 ## Copyright (C) 2009, 2010, 2011, 2012 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 ## Frequency response of SS models.
21 ## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
22 ## Created: October 2009
25 function H = __freqresp__ (sys, w, resptype = 0, cellflag = false)
27 if (sys.scaled == false)
31 [a, b, c, d, e, tsam] = dssdata (sys);
33 if (resptype != 0 && columns (b) != rows (c))
34 error ("ss: freqresp: system must be square for response type %d", resptype);
37 if (isct (sys)) # continuous system
39 else # discrete system
40 s = exp (i * w * abs (tsam));
44 case 0 # default system
45 H = arrayfun (@(x) c/(x*e - a)*b + d, s, "uniformoutput", false);
47 case 1 # inversed system
48 H = arrayfun (@(x) inv (c/(x*e - a)*b + d), s, "uniformoutput", false);
50 case 2 # inversed sensitivity
51 j = eye (columns (b));
52 H = arrayfun (@(x) j + c/(x*e - a)*b + d, s, "uniformoutput", false);
54 case 3 # inversed complementary sensitivity
55 j = eye (columns (b));
56 H = arrayfun (@(x) j + inv (c/(x*e - a)*b + d), s, "uniformoutput", false);
59 error ("ss: freqresp: invalid response type");