Part 1
I used the signal $ x = sin(t)\, $
The first sampling rate used to get a non periodic DT function was 1 Hz.
The second sampling rate used to get a periodic function was pi/3
Part 2
I chose the signal $ x(t) = t^2\, $ to make a periodic signal. Using an arbitrarily chosen period of 2, I produced the following graph
Code
y = 'sin(x)'; fplot(y,[0 10]); xlabel('t') ylabel('x(t)') title('Periodic CT Signal') sr = 1; n = 0:sr:10*sr; y = sin(n); figure(2); plot(n,y,'o-'); xlabel('n') ylabel('x(n)') title('Non-Periodic DT Signal') sr = pi/3; n = 0:sr:10*sr; y = sin(n); figure(3) plot(n,y,'o-') xlabel('n') ylabel('x(n)') title('Periodic DT Signal') %Part 2 T=2; n=0:.01:T; y = (n).^2; figure(4) hold on for k = 0:5 plot(n+k*T,y); end xlabel('t') ylabel('x(t)') title('Periodic CT Signal From Shifted Non-Periodic Signal')