cumulating / looping values in a column over all rows

Dear KNIME community,

I wonder how to cumulate gradually all values in a column over all rows. Something like the REATIN-Statement in a SAS data step or some simple loop like

for i = 2 to numberOfRows

col(i) = col(i) + col(i-1)

next i

would be quite nice.

I tried with chunkloop or TableRowToVariable-Lopp and a global variable for retaining last iterations values, I also tried with your nice lag-Operator, but everything I got is wrong and far to slow.

Do you have any better idea than me during the last helpless hours?

Thak's a lot in advance,

cheers, Martin