function [sys,x0,str,ts] = stavp_siso(t,x,u,flag,n,F,G,H,pp)

% NelinSys - a program tool for analysis and synthesis of nonlinear control systems
%            based on MATLAB/Simulink 5.2
%
% (C) 2002-2005, Martin Ondera (eskimo@pobox.sk) (Martin.Ondera@stuba.sk)

% This program 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
% of the License, or (at your option) any later version.
%
% This program 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 this program; if not, write to the Free Software
% Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
%
% Please, see the LICENSE.TXT file to read the full license.

switch flag,

% =========================== Inicializacna cast s-funkcie  ============================== %
case 0

   % Definicia stavov, vstupov a vystupov nelinearneho systemu %
   sizes = simsizes;
   sizes.NumContStates = n;
   sizes.NumDiscStates = 0;
   sizes.NumOutputs = 1+n;
   sizes.NumInputs = 1;
   sizes.DirFeedthrough = 0;
   sizes.NumSampleTimes = 1;
   sys = simsizes(sizes);

   % Inicializacia pociatocnych podmienok %
   x0 = pp;

   % Inicializacia "str" ako prazdna matica %
   str = [];
   
   % Sample times in TS %
   ts = [0 0];

% ========================== Vypocet podla 1. stavovej rovnice ========================== %
case 1
   sys = eval(sym(F)) + eval(sym(G)) * u;
   
   for k = 1 : n
      if ~isreal(sys(k,:))
         error(['At the time instant t = ',num2str(t),'s, the mathematical model of the system is no longer valid! Cannot continue the simulation!']);
      end
   end

% ========================== Vypocet podla 2. stavovej rovnice ========================== %
case 3
   sys(1,:) = eval(sym(H));       % Ako vystup bloku sa berie nielen vystup systemu...  %
   sys(2:n+1,:) = x;              % ... ale aj cely stavovy vektor nelinearneho systemu %

% ================================= Nepouzite priznaky ================================== %
case {2, 4, 9}
   sys = [];
   
% ================================= Spracovanie chyby =================================== %
otherwise
   error(['Unknown flag = ',num2str(flag)]);
end