# Copyright (C) 1996 A. Scottedward Hodel 
#
# 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, 675 Mass Ave, Cambridge, MA 02139, USA. 
 
function [systype, nout, nin, ncstates, ndstates] = minfo(inmat)
  #  function [systype, nout, nin, ncstates, ndstates] = minfo(inmat)
  #
  # MINFO:  Determines the type of system matrix.  INMAT can be
  #         a varying(*), system, constant, and empty matrix.
  #
  #    Returns:
  #      systype can be one of:
  #            varying, system, constant, and empty
  #      nout is the number of outputs of the system
  #      nin is the number of inputs of the system
  #      ncstates is the number of continuous states of the system
  #	 ndstates is the number of discrete states of the system

  # Written by R. Bruce Tenison July 29, 1994
  # Modified by David Clem November 13, 1994
  # Modified by A. S. Hodel July 1995

  warning("minfo: obsolete.  Use sys2ss, sys2tf, or sys2zp.");
    
  if (nargin ~= 1 )
    disp('MINFO: Wrong number of arguments')
    systype = nout = nin = ncstates = ndstates = [];
  endif
  
  [rr,cc] = size(inmat);
  
  # Check for empty matrix first!
  if (isempty(inmat))
    systype = "empty";
    nout = nin = ncstates = ndstates = 0;
    return
  
  # Check for Constant matrix

  elseif (rr == 1 || cc == 1)
    systype = "constant";
    nout = nin = ncstates = ndstates = 1;
    return
  
  # Check for system type matrix
  elseif (inmat(rr,cc) == -Inf)
    systype = "system";
    ncstates = inmat(1,cc);
    ndstates = inmat(rr,1);
    nstates = ncstates + ndstates;
    nout = rr - nstates - 1;
    nin = cc - nstates - 1;
  
  # Check for Varying type matrix
  elseif (inmat(rr,cc) == Inf)
    systype = "varying";
    npoints = inmat(rr,cc-1);
    nin = cc - 1;
    nout = rr / npoints;
    nstates = 0;

    # Must be a standard matrix
  else
    systype = "constant";
    nin = cc;
    nout = rr;
    ncstates = 0;
    ndstates = 0;
  endif
endfunction