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Highlights from
Signals & Systems: Continuous and Discrete, 4e Companion Software

from Signals & Systems: Continuous and Discrete, 4e Companion Software by Rodger Ziemer
Companion Software for Signals & Systems: Continuous and Discrete, 4e

[ret,x0,str,ts,xts]=c2ex23(t,x,u,flag);
function [ret,x0,str,ts,xts]=c2ex23(t,x,u,flag);
%C2EX23	is the M-file description of the SIMULINK system named C2EX23.
%	The block-diagram can be displayed by typing: C2EX23.
%
%	SYS=C2EX23(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 C2EX23 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 C2EX23 with a FLAG of zero:
%	[SIZES]=C2EX23([],[],[],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',[99,61,599,361])
     open_system(sys)
end;
set_param(sys,'algorithm',     'RK-45')
set_param(sys,'Start time',    '0.0')
set_param(sys,'Stop time',     '10')
set_param(sys,'Min step size', '0.001')
set_param(sys,'Max step size', '10')
set_param(sys,'Relative error','1e-3')
set_param(sys,'Return vars',   '[t,q]')

add_block('built-in/Note',[sys,'/','i(t)'])
set_param([sys,'/','i(t)'],...
		'position',[195,40,200,45])

add_block('built-in/Step Fcn',[sys,'/','Step Input'])
set_param([sys,'/','Step Input'],...
		'Time','0',...
		'position',[25,40,45,60])

add_block('built-in/Gain',[sys,'/','K//L'])
set_param([sys,'/','K//L'],...
		'orientation',2,...
		'position',[235,152,260,178])

add_block('built-in/Note',[sys,'/','OMEGA'])
set_param([sys,'/','OMEGA'],...
		'position',[410,40,415,45])

add_block('built-in/Scope',[sys,'/','Scope'])
set_param([sys,'/','Scope'],...
		'Vgain','0.800000',...
		'Hgain','10.000000',...
		'Vmax','1.600000',...
		'Hmax','20.000000',...
		'Window',[240,108,571,422])
open_system([sys,'/','Scope'])
set_param([sys,'/','Scope'],...
		'position',[450,50,480,80])

add_block('built-in/Gain',[sys,'/','B//J'])
set_param([sys,'/','B//J'],...
		'orientation',2,...
		'Gain','.707',...
		'position',[335,112,360,138])

add_block('built-in/Integrator',[sys,'/','Integrator2'])
set_param([sys,'/','Integrator2'],...
		'position',[370,55,390,75])

add_block('built-in/Sum',[sys,'/','Sum1'])
set_param([sys,'/','Sum1'],...
		'inputs','+-',...
		'position',[300,55,320,75])

add_block('built-in/Gain',[sys,'/','R//L'])
set_param([sys,'/','R//L'],...
		'orientation',2,...
		'Gain','.707',...
		'position',[135,112,160,138])

add_block('built-in/Gain',[sys,'/','K//J'])
set_param([sys,'/','K//J'],...
		'position',[235,47,260,73])

add_block('built-in/Integrator',[sys,'/','Integrator1'])
set_param([sys,'/','Integrator1'],...
		'position',[165,50,185,70])

add_block('built-in/Sum',[sys,'/','Sum'])
set_param([sys,'/','Sum'],...
		'inputs','+--',...
		'position',[95,42,115,78])
add_line(sys,[50,50;90,50])
add_line(sys,[120,60;160,60])
add_line(sys,[190,60;230,60])
add_line(sys,[265,60;295,60])
add_line(sys,[325,65;365,65])
add_line(sys,[395,65;445,65])
add_line(sys,[405,65;405,125;365,125])
add_line(sys,[330,125;275,125;275,70;295,70])
add_line(sys,[205,60;205,125;165,125])
add_line(sys,[405,125;405,165;265,165])
add_line(sys,[230,165;65,165;65,60;90,60])
add_line(sys,[130,125;70,125;70,70;90,70])

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

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