Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/control-2.3.52/@frd/__freqresp__.m b/octave_packages/control-2.3.52/@frd/__freqresp__.m
new file mode 100644 (file)
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+++ b/octave_packages/control-2.3.52/@frd/__freqresp__.m
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+## Copyright (C) 2010, 2012   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 FRD models :-)
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2010
+## Version: 0.2
+
+function H = __freqresp__ (sys, w, resptype = 0, cellflag = false)
+
+  [H, w_sys, tsam] = frdata (sys, "array");
+
+  if (! isempty (w))     # freqresp (frdsys, w), sigma (frdsys, w), ...
+    tol = sqrt (eps);
+    w_idx = arrayfun (@(x) find (abs (w_sys - x) < tol), w, "uniformoutput", false);
+    w_idx = vertcat (w_idx{:});
+
+    ## NOTE: There are problems when cellfun uses "uniformoutput", true
+    ##       and find returns an empty matrix,    
+
+    if (length (w_idx) != numel (w))
+      error ("frd: freqresp: some frequencies are not within tolerance %g", tol);
+    endif
+
+    H = H(:, :, w_idx);
+  endif
+
+  [p, m, l] = size (H);
+
+  if (resptype == 0)
+
+    if (cellflag)
+      H = mat2cell (H, p, m, ones (1, l))(:);
+    endif
+
+  else
+
+    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 ("frd: freqresp: invalid response type");
+    endswitch
+
+    if (! cellflag)
+      H = cat (3, H{:});
+    endif
+
+  endif
+
+endfunction