Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/control-2.3.52/isobsv.m b/octave_packages/control-2.3.52/isobsv.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{nobs}] =} isobsv (@var{sys})
+## @deftypefnx {Function File} {[@var{bool}, @var{nobs}] =} isobsv (@var{sys}, @var{tol})
+## @deftypefnx {Function File} {[@var{bool}, @var{nobs}] =} isobsv (@var{a}, @var{c})
+## @deftypefnx {Function File} {[@var{bool}, @var{nobs}] =} isobsv (@var{a}, @var{c}, @var{e})
+## @deftypefnx {Function File} {[@var{bool}, @var{nobs}] =} isobsv (@var{a}, @var{c}, @var{[]}, @var{tol})
+## @deftypefnx {Function File} {[@var{bool}, @var{nobs}] =} isobsv (@var{a}, @var{c}, @var{e}, @var{tol})
+## Logical check for system observability.
+## For numerical reasons, @code{isobsv (sys)}
+## should be used instead of @code{rank (obsv (sys))}.
+##
+## @strong{Inputs}
+## @table @var
+## @item sys
+## LTI model.  Descriptor state-space models are possible.
+## @item a
+## State transition matrix.
+## @item c
+## Measurement 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 observable.
+## @item bool = 1
+## System is observable.
+## @item nobs
+## Number of observable states.
+## @end table
+##
+## @strong{Algorithm}@*
+## Uses SLICOT AB01OD and TG01HD by courtesy of
+## @uref{http://www.slicot.org, NICONET e.V.}
+##
+## @seealso{isctrb}
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2009
+## Version: 0.4
+
+function [bool, nobs] = isobsv (a, c = [], e = [], tol = [])
+
+  if (nargin == 0)
+    print_usage ();
+  elseif (isa (a, "lti"))            # isobsv (sys), isobsv (sys, tol)
+    if (nargin > 2)
+      print_usage ();
+    endif
+    [bool, nobs] = isctrb (a.', c);  # transpose is overloaded
+  elseif (nargin < 2 || nargin > 4)
+    print_usage ();
+  else                               # isobsv (a, c), isobsv (a, c, e), ...
+    [bool, nobs] = isctrb (a.', c.', e.', tol);
+  endif
+
+endfunction
+