EE342.01: MATLAB M-FILE FOR EXAMINING DISCRETE-TIME SIGNAL PERIODICITY

%
%  Filename:  example2.m
%
%  Description:  This m-file plots various discrete-time sinusoids
%                to demonstrate periodicity.
%

n = -10:10;                        % define n values in a vector
x1 = sin(4*n);                     % define x1[n]=sin(4*n)
x2 = cos(4*pi*n/5 + 30*pi/180);    % define x2[n]=cos(4*pi*n/5+30deg)
x3 = sin(pi*pi*n + 10*pi/180);     % define x3[n]=sin(pi*pi*n+10deg)

t = -10:0.01:10;                   % define time values in vector
x4c = sin(t);                      % define continuous time sine
x4d = sin(n);                      % define samlpled version of x4c w/T=1sec

subplot(2,2,1)         % plot and label first signal
stem(n,x1)
grid
xlabel('n')
ylabel('x[n]=sin(4*n)')
title('EE342.01: Aperiodic DTS')

subplot(2,2,2)         % plot and label second signal
stem(n,x2)
grid
xlabel('n')
ylabel('x[n]=cos(4*pi*n/5 + 30deg)')
title('EE342.01: Periodic DTS')

subplot(2,2,3)         % plot and label third signal
stem(n,x3)
grid
xlabel('n')
ylabel('x[n]=sin(pi*pi*n + 10deg)')
title('EE342.01: Aperiodic DTS')

subplot(2,2,4)         % plot and label fourth signal (cont & sampled)
plot(t,x4c);
hold
stem(n,x4d)
hold
grid
xlabel('t')
ylabel('x(t)=sin(t)')
title('EE342.01: Sampled with T=1sec')