Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/control-2.3.52/@lti/minus.m b/octave_packages/control-2.3.52/@lti/minus.m
new file mode 100644 (file)
index 0000000..b6da14c
--- /dev/null
+++ b/octave_packages/control-2.3.52/@lti/minus.m
@@ -0,0 +1,47 @@
+## 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 -*-
+## Binary subtraction of LTI objects.  If necessary, object conversion
+## is done by sys_group.  Used by Octave for "sys1 - sys2".
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: September 2009
+## Version: 0.1
+
+function sys = minus (sys1, sys2)
+
+  if (nargin != 2)  # prevent sys = minus (sys1, sys2, sys3, ...)
+    error ("lti: minus: this is a binary operator");
+  endif
+
+  [p1, m1] = size (sys1);
+  [p2, m2] = size (sys2);
+
+  if (p1 != p2 || m1 != m2)
+    error ("lti: minus: system dimensions incompatible: (%dx%d) - (%dx%d)",
+            p1, m1, p2, m2);
+  endif
+
+  sys = __sys_group__ (sys1, sys2);
+
+  in_scl = [eye(m1); eye(m2)];
+  out_scl = [eye(p1), -eye(p2)];
+
+  sys = out_scl * sys * in_scl;
+
+endfunction