ex9_12.m

基于WEB与MATLAB编写的信号处理的源码,书名为"应用WEB和MATLAB的信号与系统基础.

%  Example 9.12
% second order response
%  varying zeta, wn is constant
t = 0:.05:20;
wn = 1;
zeta = .1;
num = wn^2; den = [1 2*zeta*wn wn^2];
y1 = step(num,den,t);
wn = 1;
zeta = .25;
num = wn^2; den = [1 2*zeta*wn wn^2];
y2 = step(num,den,t);
wn = 1;
zeta =.7; 
num = wn^2; den = [1 2*zeta*wn wn^2];
y3 = step(num,den,t);
plot(t,y1,'-',t,y2,'--',t,y3,'-.');
xlabel('Time (sec)')
ylabel('y(t)')
title('Second order step response')
% the following inserts a legend
hold on
plot([9 11],[.5 .5],[9 11],[.4 .4],'--',[9 11],[.3 .3],'-.');
text(12,.5,'zeta = 0.1')
text(12,.4,'zeta = 0.25')
text(12,.3,'zeta = 0.7')
hold off