Aggregation???

[#1]

Hello all, need help with some mathematical functions.

Is there a way to realise the next aggregation?

It's a straight table, two columns.

a (1) a(1)

a (2) a(2)-a(1)

a (3) a(3)-a(2)

Thanks.

[sparur]

If I understand you can use something like this:

Sum(Amount) - above(Sum(Amount))