Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / @lti / mpower.m

diff --git a/octave_packages/control-2.3.52/@lti/mpower.m b/octave_packages/control-2.3.52/@lti/mpower.m
new file mode 100644 (file)
index 0000000..a1aa4ca
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+++ b/octave_packages/control-2.3.52/@lti/mpower.m
@@ -0,0 +1,59 @@
+## Copyright (C) 2009   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 -*-
+## Matrix power of LTI objects.  The exponent must be an integer.
+## Used by Octave for "sys^int".
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2009
+## Version: 0.1
+
+function retsys = mpower (sys, e)
+
+  if (nargin != 2)       # prevent sys = mpower (a, b, c, ...)
+    error ("lti: mpower: this is a binary operator");
+  endif
+
+  if (! is_real_scalar (e) || e != round (e))
+    error ("lti: mpower: exponent must be an integer");
+  endif
+
+  [p, m] = size (sys);
+  
+  if (p != m)
+    error ("lti: mpower: system must be square");
+  endif
+
+  ex = round (abs (e));  # make sure ex is a positive integer
+
+  switch (sign (e))
+    case -1              # lti^-ex
+      sys = inv (sys);
+      retsys = sys;
+    case 0               # lti^0
+      retsys = eye (p);
+      return;
+    case 1               # lti^ex
+      retsys = sys;
+  endswitch
+    
+  for k = 2 : ex
+    retsys = retsys * sys;
+  endfor
+
+endfunction