## Copyright (C) 1996, 1997 John W. Eaton
##
## This file is part of Octave.
##
## Octave 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 2, or (at your option)
## any later version.
##
## Octave 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 Octave; see the file COPYING.  If not, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA
## 02111-1307, USA.

## usage: is_observable (a, c {,tol})
##
## Returns 1 if the pair (a, c) is observable, or 0 if not.
##
## See also: size, rows, columns, length, is_matrix, is_scalar, is_vector.

## Author: A. S. Hodel <scotte@eng.auburn.edu>
## Created: August 1993
## Adapted-By: jwe

function retval = is_observable (a,c,tol)

  if (nargin == 2)
    retval = is_controllable (a', c');
  elseif (nargin == 3)
    retval = is_controllable (a', c', tol);
  else
    usage ("is_observable (a, c {,tol})");
  endif

endfunction