Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / isctrb.m

diff --git a/octave_packages/control-2.3.52/isctrb.m b/octave_packages/control-2.3.52/isctrb.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 -*-
+## @deftypefn {Function File} {[@var{bool}, @var{ncon}] =} isctrb (@var{sys})
+## @deftypefnx {Function File} {[@var{bool}, @var{ncon}] =} isctrb (@var{sys}, @var{tol})
+## @deftypefnx {Function File} {[@var{bool}, @var{ncon}] =} isctrb (@var{a}, @var{b})
+## @deftypefnx {Function File} {[@var{bool}, @var{ncon}] =} isctrb (@var{a}, @var{b}, @var{e})
+## @deftypefnx {Function File} {[@var{bool}, @var{ncon}] =} isctrb (@var{a}, @var{b}, @var{[]}, @var{tol})
+## @deftypefnx {Function File} {[@var{bool}, @var{ncon}] =} isctrb (@var{a}, @var{b}, @var{e}, @var{tol})
+## Logical check for system controllability.
+## For numerical reasons, @code{isctrb (sys)}
+## should be used instead of @code{rank (ctrb (sys))}.
+##
+## @strong{Inputs}
+## @table @var
+## @item sys
+## LTI model.  Descriptor state-space models are possible.
+## @item a
+## State transition matrix.
+## @item b
+## Input matrix.
+## @item e
+## Descriptor matrix.
+## If @var{e} is empty @code{[]} or not specified, an identity matrix is assumed.
+## @item tol
+## Optional roundoff parameter.  Default value is 0.
+## @end table
+##
+## @strong{Outputs}
+## @table @var
+## @item bool = 0
+## System is not controllable.
+## @item bool = 1
+## System is controllable.
+## @item ncon
+## Number of controllable states.
+## @end table
+##
+## @strong{Algorithm}@*
+## Uses SLICOT AB01OD and TG01HD by courtesy of
+## @uref{http://www.slicot.org, NICONET e.V.}
+##
+## @seealso{isobsv}
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2009
+## Version: 0.4
+
+function [bool, ncont] = isctrb (a, b = [], e = [], tol = [])
+
+  if (nargin < 1 || nargin > 4)
+    print_usage ();
+  elseif (isa (a, "lti"))  # isctrb (sys), isctrb (sys, tol)
+    if (nargin > 2)
+      print_usage ();
+    endif
+    tol = b;
+    [a, b, c, d, e] = dssdata (a, []);
+  elseif (nargin < 2)      # isctrb (a, b), isctrb (a, b, tol)
+    print_usage ();
+  elseif (! is_real_square_matrix (a) || ! is_real_matrix (b) || rows (a) != rows (b))
+    error ("isctrb: a(%dx%d), b(%dx%d) not conformal",
+            rows (a), columns (a), rows (b), columns (b));
+  elseif (! isempty (e) && (! is_real_square_matrix (e) || ! size_equal (e, a)))
+    error ("isctrb: a(%dx%d), e(%dx%d) not conformal",
+            rows (a), columns (a), rows (e), columns (e));
+  endif
+
+  if (isempty (tol))
+    tol = 0;               # default tolerance
+  elseif (! is_real_scalar (tol))
+    error ("isctrb: tol must be a real scalar");
+  endif
+
+  if (isempty (e))
+    [~, ~, ~, ncont] = slab01od (a, b, tol);
+  else
+    [~, ~, ~, ~, ~, ~, ncont] = sltg01hd (a, e, b, zeros (1, columns (a)), tol);
+  endif
+
+  bool = (ncont == rows (a));
+
+endfunction