This signal has a sampling frequency that is too small and so that the signal is non periodic. However, after changing the sampling frequency to 0.07/250, the signal becomes periodic because the signal repeats itself.
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)
F0 =13; T0 =1/F0; Ts = 0.07/250; t = 0:Ts:13*T0; x = real(exp(j*(2*pi*F0*t-pi/2))); plot(t,x)
