Average of selected elements in Matlab

I have a data file, first column is Month, second column is Demand. I want to calculate the Moving Average of month 4 (=(month 1+2+3)/3) and so on. Then, I want to display the results in the 3rd column. How can I do?

Instead of using Excel, I want to use Matlab to calculate this. Please help me :(((

Answer 1

[weikang zhao]

easy, use "conv"

x=conv(a(:,2),[1/3,1/3,1/3]);

the first element and the second element of 'x' are useless.

have fun

[Hoai An Nguyen]

Thank you so much <3 But how can I display 3 column?

(So sorry if my English is not good to explain what I need :<<)

[weikang zhao]

Add a line of code

a(:,3)=[nan,nan,nan,x(3:11)].';

[Hoai An Nguyen]

It has a problem... :(

[weikang zhao]

opps, 'x' is a column vector

a(:,3)=[nan,nan,nan,x(3:11).'].';