Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / @tf / __freqresp__.m

diff --git a/octave_packages/control-2.3.52/@tf/__freqresp__.m b/octave_packages/control-2.3.52/@tf/__freqresp__.m
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+++ b/octave_packages/control-2.3.52/@tf/__freqresp__.m
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+## Copyright (C) 2009, 2010, 2011   Lukas F. Reichlin
+##
+## This file is part of LTI Syncope.
+##
+## LTI Syncope is free software: you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## LTI Syncope is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with LTI Syncope.  If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## Frequency response of TF models.
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2009
+## Version: 0.4
+
+function H = __freqresp__ (sys, w, resptype = 0, cellflag = false)
+
+  [num, den, tsam] = tfdata (sys, "vector");
+
+  if (isct (sys))  # continuous system
+    s = i * w;
+  else             # discrete system
+    s = exp (i * w * abs (tsam));
+  endif
+  
+  s = reshape (s, 1, 1, []);
+
+  if (issiso (sys))
+    H = polyval (num, s) ./ polyval (den, s);
+  else
+    H = cellfun (@(x, y) polyval (x, s) ./ polyval (y, s), num, den, "uniformoutput", false);
+    H = cell2mat (H);
+  endif
+
+  if (resptype)
+    [p, m] = size (sys);
+    l = length (s); 
+    if (m != p)
+      error ("tf: freqresp: system must be square for response type %d", resptype);
+    endif 
+    H = mat2cell (H, p, m, ones (1, l))(:);
+    j = eye (p);
+    switch (resptype)
+      case 1     # inversed system
+        H = cellfun (@inv, H, "uniformoutput", false);
+      case 2     # inversed sensitivity
+        H = cellfun (@(x) j + x, H, "uniformoutput", false);
+      case 3     # inversed complementary sensitivity
+        H = cellfun (@(x) j + inv (x), H, "uniformoutput", false);
+      otherwise
+        error ("tf: freqresp: invalid response type");
+    endswitch
+    if (! cellflag)
+      H = cat (3, H{:});
+    endif
+  elseif (cellflag)
+    [p, m] = size (sys);
+    l = length (s);
+    H = mat2cell (H, p, m, ones (1, l))(:);
+  endif
+
+endfunction