sin_d.m

经典《信号与系统》教程的matlab例程,对深入理解信号与系统相关概念有很大帮助

% Name: sin_d.m
clear,close all,
n=-20:20;
x1=cos(2*pi*n/12);
x2=cos(8*pi*n/31);
x3=cos(n/6);
subplot(311)
stem(n,x1,'r.'),axis([-20,20,-1.2,1.2])
title('Three examples of sinusoidal sequences')
subplot(312)
stem(n,x2,'r.'),axis([-20,20,-1.2,1.2])
subplot(313)
stem(n,x3,'r.'),axis([-20,20,-1.2,1.2])
xlabel('Time n')

x4=(1.1.^n).*cos(3*n/4);
x5=(0.9.^n).*cos(3*n/4);
x6=(1.1.^n);
x7=(0.9.^n);


figure(2)
subplot(221)
stem(n,x4,'r.'),hold on,plot(n,x6,'b:'),hold on,plot(n,-x6,'b:'),
title('Growing sinusoidal sequences')
xlabel('Time n')
subplot(222)
stem(n,x5,'r.'),hold on,plot(n,x7,'b:'),hold on,plot(n,-x7,'b:'),
xlabel('Time n')
title('Decaying sinusoidal sequences')