## Copyright (C) 1996,1998 Auburn University.  All Rights Reserved.
##
## 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 USA.

## -*- texinfo -*-
## @deftypefn {Function File } { [@var{n}, @var{nz}, @var{m}, @var{p},@var{yd}] =} sysdimensions (@var{sys}@{, @var{opt}@})
##  return the number of states, inputs, and/or outputs in the system @var{sys}.
## 
## @strong{Inputs}
## @table @var
## @item sys
##  system data structure
## 
## @item opt
## String indicating which dimensions are desired.  Values:
## @table @code
## @item "all"
## (default) return all parameters as specified under Outputs below.
## 
## @item "cst"  
## return @var{n}= number of continuous states
## 
## @item "dst"  
## return @var{n}= number of discrete states
## 
## @item "in"
## return @var{n}= number of inputs
## 
## @item "out"
## return @var{n}= number of outputs
## @end table
## @end table
## 
## @strong{Outputs}
## @table @var
## @item  n
##  number of continuous states (or individual requested dimension as specified
## by @var{opt}).
## @item  nz
##  number of discrete states
## @item  m
##  number of system inputs
## @item  p
##  number of system outputs
## @item  yd
##  binary vector; @var{yd}(@var{ii}) is nonzero if output @var{ii} is
## discrete.
## @math{yd(ii) = 0} if output @var{ii} is continous
## @end table
## 
## @end deftypefn

## See also: sysgetsignals, sysgettsam

function [n,nz,m,p,yd] = sysdimensions(sys,opt)
if(nargout > 5 | nargin < 1 | nargin > 2)
  usage("[n,nz,m,p[,yd]] = sysdimensions(sys{,opt})");
elseif(!is_struct(sys))
  usage("[n,nz,m,p] = sysdimensions(sys)");
elseif(nargin == 1)
  opt = "all";
endif

n = sys.n;
nz = sys.nz;
m = length(sysgetsignals(sys,"in"));
p = length(sysgetsignals(sys,"out"));
yd = sys.yd;
legal_options = list("all","cst","dst","st","in","out");
legal_values = list(n,n,nz,n+nz,m,p);

legal_opt = 0;
for ii=1:length(legal_options)
  if(strcmp(nth(legal_options,ii),opt))
    n = nth(legal_values,ii);
    legal_opt = 1;
    if(ii > 1 & nargout > 1)
      warning("opt=%s, %d output arguments requested",opt,nargout);
    endif
  endif
endfor
if(!legal_opt)
  error("illegal option passed = %s",opt);
endif

endfunction