compute the autocorrelation without using corr and plot the convolved sequence

Write a MATLAB program to compute the autocorrelation of the following sequence x=[1 2 3 4 5 6]

(a) Plot the signal x and y using stem plots as two subplots in a single figure window (Note : Do not use built in function ‘xcorr’ in MATLAB)

(b) Plot the convolved sequence in a separate figure window