Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/control-2.3.52/@ss/__minreal__.m b/octave_packages/control-2.3.52/@ss/__minreal__.m
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+++ b/octave_packages/control-2.3.52/@ss/__minreal__.m
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+## Copyright (C) 2009, 2010   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 -*-
+## Minimal realization of SS models.  The physical meaning of states is lost.
+## Uses SLICOT TB01PD and TG01JD by courtesy of
+## @uref{http://www.slicot.org, NICONET e.V.}
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2009
+## Version: 0.3
+
+function retsys = __minreal__ (sys, tol)
+
+  if (tol == "def")
+    tol = 0;
+  elseif (tol > 1)
+    error ("ss: minreal: require tol <= 1");
+  endif
+
+  if (isempty (sys.e))
+    [a, b, c] = sltb01pd (sys.a, sys.b, sys.c, tol, sys.scaled);
+    retsys = ss (a, b, c, sys.d);
+  else
+    [a, e, b, c] = sltg01jd (sys.a, sys.e, sys.b, sys.c, tol, sys.scaled, 0, 0);
+    retsys = dss (a, b, c, sys.d, e);
+  endif
+
+  retsys.lti = sys.lti;  # retain i/o names and tsam
+
+endfunction