# MATLAB: Superimpose two plots having different vector lengths

beginnerMATLABplotsignal processingsuperimpose plot

Hello,
I am new with Matlab and try using it for practicing pedagogy exercises about signal processing. Unfortunately I am stuck at this point :
I try to superimpose a chirp signal (signal with increasing frequency rate) and an aliased signal of this same chirp signal onto the same plot using the "hold on" function. Unfortunately an error occurs : "Error using plot ; Vectors must be the same length". I have tried several alternatives and read similar questions without understanding how to circumvent this little issue. I understand that there is some incompatibility between my two signals, related to their respective axes I guess. I put my code below for more understanding. Also, I precise that I only want to use the hold on function and not alternatives in order to learn how to use it :
``Fs = 200 % sampling frequencyt = 0:1/Fs:1x = chirp(t,0,1,Fs/6)dx = x(1:20:end)subplot(3,1,1,'align');plot(t,x), xlabel('Time(sec)');ylabel('Amplitude');title('Chirp Signal')hold on; % here is my problemplot(t,dx)subplot(3,1,2); % display same plot with discrete valuesstem(x)subplot(3,1,3); % display the power of frequency componentspwelch(x)``

``plot(t(1:20:end), dx)``