matlab 2009 10 22 02

% program file lab2009102202.m
clear all;
% clf;
dt = 0.0001;
t =-0.01:dt:0.02;
xc = cos(2*pi*100*t);
tt = 0.0005;
ts = -0.01:tt:0.02;
xd = cos(2*pi*100*ts);

n=-20:1:40;
x4 = cos(2*pi*100*n*tt);

figure(1);
subplot(311);
plot(t,xc);

subplot(312);
stem(ts,xd);

subplot(313);
stem(n,x4);