addfig211.m

realize analysis and design for computer-controlled system

% Generates Fig 2.11 
% Computer Controlled Systems (3rd ed)
% Author: B. Wittenmark
% Last edit: 1997-06-27
% Copyright (c) 1996 by K. J. 舠tr鰉, B. Wittenmark and
% Department of Automatic Control, Lund Institute of
% Technology, Lund, Sweden

newplot;clf
set(gcf,'PaperUnits','centimeters','PaperPosition',[2 2 13 8])
set(gcf,'Units','centimeters','position',get(gcf,'PaperPosition'))

lw=0.9;

A=[-2 -2 -1;1 0 0; 0 1 0];
B=[1; 0; 0];
C=[0 0 1];
D=0;

h=0.0001;
[phi,ga]=c2d(A,B,h);
p = eig(phi);
z = tzero(phi,ga,C,D);
hpl=plot(real(p),imag(p),'kx',real(z),imag(z),'ko','Linew',lw);
set(hpl,'MarkerSize',5)
axis([-4 1 -1.5 1.5])
hold on


hvec=[0.2 0.5 1 2 3];

for i=1:5
h=hvec(i);
[phi,ga]=c2d(A,B,h);
p = eig(phi);
z = tzero(phi,ga,C,D);
hpl=plot(real(p),imag(p),'kx',real(z),imag(z),'ko','Linew',lw);
set(hpl,'MarkerSize',5)
end

cir=[0 0];
for k=1:37,arg=2*pi/36*(k-1);cir(k,:)=[sin(arg) cos(arg)];end
hpl=plot(cir(:,1),cir(:,2),'Linew',lw);
xlabel('Real axis','Fontsize',9,'Fontname','NewCenturySchlbk')
ylabel('Imaginary axis','Fontsize',9,'Fontname','NewCenturySchlbk')
set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'xtick',[-4 -3 -2 -1 0 1],'ytick',[-2 -1 0 1 2]);
axis('equal');
limits=axis;
plot([0 0],[-2 2],'k:',[-4 1],[0 0],'k:')

%title(['Fig 3.11']);
text(-3.9,0.2,'h=0+','Fontsize',9,'Fontname','NewCenturySchlbk','fontan','ital') 
text(-0.4,0.25,'h=0+','Fontsize',9,'Fontname','NewCenturySchlbk','fontan','ital')
text(1.1,0.2,'h=0+','Fontsize',9,'Fontname','NewCenturySchlbk','fontan','ital') 
hold off