plot summation of shifted discrete signals

 n=-4:2;
 y=[1,-2,4,6,-5,8,10];
 n=n-2
 stem(n,y);

I want to plot Z = y(n-2)+y(n+1);

Answer 1

[Hamoon]

 n=-4:2;
 y=[1,-2,4,6,-5,8,10];

 maxShift = 10;                         % maximum shift that you may want,
                                        % you can't shift more than this value,
                                        % you should set this value high enough
                                        % I could set it to be 2 here, but I prefer 10 

 n=min(n)-maxShift:1:max(n)+maxShift;          % define proper range for n
 y=[zeros(1,maxShift), y, zeros(1,maxShift)];  % add zeros to the begining and
                                               % end of y 

 z= circshift(y',-2) + circshift(y',1);  % calculate your new signal. you need
                                         % transpose of y ==> y'

[Hamoon]

here is the output using:

subplot(2,1,1)
stem(n,y);
title('y')
axis([-15 15 -10 20])
subplot(2,1,2)
stem(n,z);
title('z')
axis([-15 15 -10 20])

[Nguyen Hong Son]

Excuse me. Can I ask you why we can use circular shift to compute operations of shifted discrete signals? (I can't have the intuition or visualization of it)

Why do we need the transpose of y in the last line of code?

Thank you so much!