fig28.m

realize analysis and design for computer-controlled system

% Generates Fig 2.8
% Computer Controlled Systems (3rd ed)
% Author: B. Wittenmark
% Last edit: 1997-08-05
% 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;

zeta = 0:.1:1.0;
wn = 0:pi/10:pi;

m = tan(asin(zeta));
zz = exp((0:pi/40:pi)'*(-m + sqrt(-1)*ones(1,length(m))));
plot(real(zz),imag(zz),'k-','Linew',lw);
axis([-1 1 0 1]);
axis('equal')
hold on

e_itheta = exp(sqrt(-1)*(pi/2:pi/100:pi)');
e_r = exp(wn);
zw = (ones(length(e_itheta), 1)*e_r).^(e_itheta*ones(1,length(e_r)));
plot(real(zw),imag(zw),'k--','Linew',lw);
grid

set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'xtick',[-1 -0.5 0 0.5 1],'ytick',[0 0.5 1]);
xlabel('Real axis','Fontsize',9,'Fontname','NewCenturySchlbk')
ylabel('Imaginary axis','Fontsize',9,'Fontname','NewCenturySchlbk')
%title('Fig 2.8','Fontname','NewCenturySchlbk');

x=[ 0.33 0.48 0.48 0.33];
y=[0.89 0.89 0.97 0.97];
hpl=patch(x,y,'w');
set(hpl,'edgecolor','none');
text(0.34,0.93,'\zeta = 0','fontname','NewCenturySchlbk','fontsize',9)
x=[0.27 0.49 0.49 0.27];
y=[0.67 0.67 0.75 0.75];
hpl=patch(x,y,'w');
set(hpl,'edgecolor','none');
text(0.28,0.71,'\zeta = 0.2','fontname','NewCenturySchlbk','fontsize',9)
x=[0.25 0.47 0.47 0.25];
y=[0.51 0.51 0.58 0.58];
hpl=patch(x,y,'w');
set(hpl,'edgecolor','none');
text(0.265,0.55,'\zeta = 0.4','fontname','NewCenturySchlbk','fontsize',9)
x=[0.25 0.48 0.48 0.25];
y=[0.35 0.35 0.43 0.43];
hpl=patch(x,y,'w');
set(hpl,'edgecolor','none');
text(0.27,0.40,'\zeta = 0.6','fontname','NewCenturySchlbk','fontsize',9)
x=[0.25 0.47 0.47 0.25];
y=[0.21 0.21 0.29 0.29];
hpl=patch(x,y,'w');
set(hpl,'edgecolor','none');
text(0.265,0.255,'\zeta = 0.8','fontname','NewCenturySchlbk','fontsize',9)
x=[0.25 0.48 0.48 0.25];
y=[-0.04 -0.04 0.04 0.04];
hpl=patch(x,y,'w');
set(hpl,'edgecolor','none');
text(0.27,0.005,'\zeta = 1.0','fontname','NewCenturySchlbk','fontsize',9)