%an example to generate a sinusoid signalclear;%magnitude is AA = 5;%f_sig is the frequency of the signal, T_sig is the corresponding periodf_sig = 3; T_sig = 1/f_sig;%T_max is the maximum number of timeT_max = 2*T_sig;%Ts is the sampling interval of the continuous time signal (Fs is sampling%rate)Ts = 1e-3;  Fs = 1/Ts;%generate time vectort = -T_max:Ts:T_max;%a complicated way to generate the signal vector by setting the values of%the vector element by elementt_len = length(t);mid_point = (t_len+1)/2;for i = 1:t_len    t_now = (i-mid_point)*Ts;    cos_t(i) = A*cos(2*pi*f_sig*t_now);end%a much easier way to generate the signal vector by setting the vector%directly.vector_sig = A*sin(2*pi*f_sig*t);%plot the signalplot(t, cos_t);hold on;    grid on;plot(t, vector_sig,'r');ylabel('x(t)');xlabel('t (sec)');ylim([-A*1.1, A*1.1]);