1 ## Copyright (C) 2009, 2010, 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 ## Frequency response of TF models.
21 ## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
22 ## Created: October 2009
25 function H = __freqresp__ (sys, w, resptype = 0, cellflag = false)
27 [num, den, tsam] = tfdata (sys, "vector");
29 if (isct (sys)) # continuous system
31 else # discrete system
32 s = exp (i * w * abs (tsam));
35 s = reshape (s, 1, 1, []);
38 H = polyval (num, s) ./ polyval (den, s);
40 H = cellfun (@(x, y) polyval (x, s) ./ polyval (y, s), num, den, "uniformoutput", false);
48 error ("tf: freqresp: system must be square for response type %d", resptype);
50 H = mat2cell (H, p, m, ones (1, l))(:);
53 case 1 # inversed system
54 H = cellfun (@inv, H, "uniformoutput", false);
55 case 2 # inversed sensitivity
56 H = cellfun (@(x) j + x, H, "uniformoutput", false);
57 case 3 # inversed complementary sensitivity
58 H = cellfun (@(x) j + inv (x), H, "uniformoutput", false);
60 error ("tf: freqresp: invalid response type");
68 H = mat2cell (H, p, m, ones (1, l))(:);