Cumulative Sum of a Vector - Syntax

Question

I am trying to resolve why the following Matlab syntax does not work.

1. I have an array A = [2 3 4 5 8 9...]
2. I wish to create an indexed cumulative, for

Answer 1

For calculating the cumulative sum, you should be using cumsum:

>> A = [2 3 4 5 8 9]

A =

     2     3     4     5     8     9

>> cumsum(A)

ans =

     2     5     9    14    22    31

The issue is that 1:x is 1 and that sum reduces linear arrays. To do this properly, you need a 2d array and then sum the rows:

s(x)=sum(triu(repmat(A,[prod(size(A)) 1])'))