Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / @ss / __sys2tf__.m

diff --git a/octave_packages/control-2.3.52/@ss/__sys2tf__.m b/octave_packages/control-2.3.52/@ss/__sys2tf__.m
new file mode 100644 (file)
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+++ b/octave_packages/control-2.3.52/@ss/__sys2tf__.m
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+## Copyright (C) 2009, 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 -*-
+## SS to TF conversion.
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2009
+## Version: 0.3
+
+function [retsys, retlti] = __sys2tf__ (sys)
+
+  try
+    [a, b, c, d, tsam, scaled] = ssdata (sys);  # system could be a descriptor model
+
+    [num, den, ign, igd, md, p, m] = sltb04bd (a, b, c, d, scaled);
+
+    num = reshape (num, md, p, m);
+    den = reshape (den, md, p, m);
+
+    num = mat2cell (num, md, ones(1,p), ones(1,m));
+    den = mat2cell (den, md, ones(1,p), ones(1,m));
+
+    num = squeeze (num);
+    den = squeeze (den);
+
+    ign = mat2cell (ign, ones(1,p), ones(1,m));
+    igd = mat2cell (igd, ones(1,p), ones(1,m));
+
+    num = cellfun (@(x, y) x(1:y+1), num, ign, "uniformoutput", false);
+    den = cellfun (@(x, y) x(1:y+1), den, igd, "uniformoutput", false);
+  catch
+    ## sys.e was probably singular, therefore ssdata failed.
+    if (issiso (sys))
+      [num, den] = __siso_ss2tf__ (sys);
+    else
+      [p, m] = size (sys);
+      num = cell (p, m);
+      den = cell (p, m);
+      for i = 1 : p
+        for j = 1 : m
+          idx = substruct ("()", {i, j});
+          tmp = subsref (sys, idx);             # extract siso model
+          tmp = minreal (tmp);                  # irreducible descriptor representation
+          [n, d] = __siso_ss2tf__ (tmp);
+          num(i, j) = n;
+          den(i, j) = d;
+        endfor
+      endfor
+    endif
+    tsam = get (sys, "tsam");
+  end_try_catch
+
+  retsys = tf (num, den, tsam);                 # tsam needed to set appropriate tfvar
+  retlti = sys.lti;                             # preserve lti properties
+  
+  ## FIXME: sys = tf (ss (5))
+
+endfunction
+
+
+function [num, den] = __siso_ss2tf__ (sys)
+
+  if (isempty (sys.a))                          # static gain
+    num = sys.d;
+    den = 1;
+  else                                          # default case
+    [zer, gain] = zero (sys);
+    pol = pole (sys);
+    num = gain * real (poly (zer));
+    den = real (poly (pol));
+  endif
+
+endfunction