The Problem
The following code has a bug that prevents it from working properly.
F0 =13; T0 =1/F0; Ts = 0.07; t = 0:Ts:13*T0; x = real(exp(j*(2*pi*F0*t-pi/2))); plot(t,x)
The Solution
Ts is much too large for this application. The value of 0.07 that is given in the original code is nearly the size of one cycle. Reducing Ts by a factor of 100 would greatly help.
The final code should look something like this:
F0 =13; T0 =1/F0; Ts = 0.0007; t = 0:Ts:13*T0; x = real(exp(j*(2*pi*F0*t-pi/2))); plot(t,x)