c2ex19.m

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function [ret,x0,str,ts,xts]=ex2_20(t,x,u,flag);
%EX2_20	is the M-file description of the SIMULINK system named EX2_20.
%	The block-diagram can be displayed by typing: c2ex19.
%
%	SYS=EX2_20(T,X,U,FLAG) returns depending on FLAG certain
%	system values given time point, T, current state vector, X,
%	and input vector, U.
%	FLAG is used to indicate the type of output to be returned in SYS.
%
%	Setting FLAG=1 causes EX2_20 to return state derivatives, FLAG=2
%	discrete states, FLAG=3 system outputs and FLAG=4 next sample
%	time. For more information and other options see SFUNC.
%
%	Calling EX2_20 with a FLAG of zero:
%	[SIZES]=EX2_20([],[],[],0),  returns a vector, SIZES, which
%	contains the sizes of the state vector and other parameters.
%		SIZES(1) number of states
%		SIZES(2) number of discrete states
%		SIZES(3) number of outputs
%		SIZES(4) number of inputs
%		SIZES(5) number of roots (currently unsupported)
%		SIZES(6) direct feedthrough flag
%		SIZES(7) number of sample times
%
%	For the definition of other parameters in SIZES, see SFUNC.
%	See also, TRIM, LINMOD, LINSIM, EULER, RK23, RK45, ADAMS, GEAR.

% Note: This M-file is only used for saving graphical information;
%       after the model is loaded into memory an internal model
%       representation is used.

% the system will take on the name of this mfile:
sys = mfilename;
new_system(sys)
simver(1.3)
if (0 == (nargin + nargout))
     set_param(sys,'Location',[55,175,555,475])
     open_system(sys)
end;
set_param(sys,'algorithm',     'RK-45')
set_param(sys,'Start time',    '0.0')
set_param(sys,'Stop time',     '30')
set_param(sys,'Min step size', '0.0001')
set_param(sys,'Max step size', '10')
set_param(sys,'Relative error','1e-3')
set_param(sys,'Return vars',   '[t,x,y]')

add_block('built-in/Step Fcn',[sys,'/','Step Input'])
set_param([sys,'/','Step Input'],...
		'Time','0',...
		'position',[50,35,70,55])

add_block('built-in/Gain',[sys,'/','1//C'])
set_param([sys,'/','1//C'],...
		'position',[115,32,140,58])

add_block('built-in/Integrator',[sys,'/','Integrator1'])
set_param([sys,'/','Integrator1'],...
		'position',[95,105,115,125])

add_block('built-in/Gain',[sys,'/','1//RC'])
set_param([sys,'/','1//RC'],...
		'orientation',2,...
		'position',[280,172,305,198])

add_block('built-in/Gain',[sys,'/','1//LC'])
set_param([sys,'/','1//LC'],...
		'orientation',2,...
		'Gain','.5',...
		'position',[190,232,215,258])

add_block('built-in/Sum',[sys,'/','Sum'])
set_param([sys,'/','Sum'],...
		'inputs','+--',...
		'position',[215,87,235,143])

add_block('built-in/Integrator',[sys,'/','Integrator2'])
set_param([sys,'/','Integrator2'],...
		'position',[330,105,350,125])

add_block('built-in/Scope',[sys,'/','Scope'])
set_param([sys,'/','Scope'],...
		'Vgain','1.000000',...
		'Hgain','30.000000',...
		'Vmax','2.000000',...
		'Hmax','60.000000',...
		'Window',[383,276,714,590])
open_system([sys,'/','Scope'])
set_param([sys,'/','Scope'],...
		'position',[425,100,455,130])

add_block('built-in/Note',[sys,'/','y'])
set_param([sys,'/','y'],...
		'position',[405,125,410,130])
add_line(sys,[75,45;110,45])
add_line(sys,[185,245;70,245;70,115;90,115])
add_line(sys,[275,185;190,185;190,135;210,135])
add_line(sys,[240,115;325,115])
add_line(sys,[355,115;420,115])
add_line(sys,[385,115;385,185;310,185])
add_line(sys,[385,185;385,245;220,245])
add_line(sys,[120,115;210,115])
add_line(sys,[145,45;170,45;170,95;210,95])

drawnow

% Return any arguments.
if (nargin | nargout)
	% Must use feval here to access system in memory
	if (nargin > 3)
		if (flag == 0)
			eval(['[ret,x0,str,ts,xts]=',sys,'(t,x,u,flag);'])
		else
			eval(['ret =', sys,'(t,x,u,flag);'])
		end
	else
		[ret,x0,str,ts,xts] = feval(sys);
	end
else
	drawnow % Flash up the model and execute load callback
end