fig34.m

realize analysis and design for computer-controlled system

% Generates Fig 3.4
% 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 9.5])
set(gcf,'Units','centimeters','position',get(gcf,'PaperPosition'))

lw=0.9;

m=200;
h=0.4;
w1=logspace(-4,pi,m)/h;
ac=[-1.4 -1;1 0];bc=[1;0];cc=[0 1];dc=0;
[ph,ga]=c2d(ac,bc,h);
[mag1,ph1,w1]=dbode(ph,ga,cc,dc,h,1,w1);

w2=logspace(-4,2,m);
[mag2,ph2,w2]=bode(ac,bc,cc,dc,1,w2);

subplot(2,1,1)
loglog(w1,mag1,'m-',w2,mag2,'k--','Linew',lw)
axis([0.05 10 0.001 5])
%title('Bode plot');
hold on
plot([0.01 50],[1 1],'k:')
set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'ytick',[0.01 1]);
set(gca,'xtick',[0.1 1 10]);
ylabel('Gain','Fontname','NewCenturySchlbk','Fontsize',9)

subplot(2,1,2)
semilogx(w1,ph1,'m-',w2,ph2,'k--','Linew',lw)
axis([0.05 10 -250 50]);
hold on
plot([0.01 50],[-180 -180],'k:')
set(gca,'Fontsize',9,'Fontname','NewCenturySchlbk');
set(gca,'xtick',[0.1 1 10]);
set(gca,'ytick',[-180 0]);
xlabel('Frequency, rad/s','Fontname','NewCenturySchlbk','Fontsize',9)
ylabel('Phase','Fontname','NewCenturySchlbk','Fontsize',9)
drawnow;
%
ylblalgn;