If you have an array like [4,9,7,2], how do you get an array like [4,13,20,22], where each element is the cumulative sum of elements in the first array?
One possible approach would be to use a Repeat with Counter with Select SubArray in Array.
eX-SI
ICE, scripting, and other tech stuff about Softimage aka XSI
eX-SI 
Nice one, Stephen! thanks