1 ## Copyright (C) 2010, 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 FRD models :-)
21 ## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
22 ## Created: October 2010
25 function H = __freqresp__ (sys, w, resptype = 0, cellflag = false)
27 [H, w_sys, tsam] = frdata (sys, "array");
29 if (! isempty (w)) # freqresp (frdsys, w), sigma (frdsys, w), ...
31 w_idx = arrayfun (@(x) find (abs (w_sys - x) < tol), w, "uniformoutput", false);
32 w_idx = vertcat (w_idx{:});
34 ## NOTE: There are problems when cellfun uses "uniformoutput", true
35 ## and find returns an empty matrix,
37 if (length (w_idx) != numel (w))
38 error ("frd: freqresp: some frequencies are not within tolerance %g", tol);
49 H = mat2cell (H, p, m, ones (1, l))(:);
55 error ("tf: freqresp: system must be square for response type %d", resptype);
58 H = mat2cell (H, p, m, ones (1, l))(:);
62 case 1 # inversed system
63 H = cellfun (@inv, H, "uniformoutput", false);
65 case 2 # inversed sensitivity
66 H = cellfun (@(x) j + x, H, "uniformoutput", false);
68 case 3 # inversed complementary sensitivity
69 H = cellfun (@(x) j + inv (x), H, "uniformoutput", false);
72 error ("frd: freqresp: invalid response type");