[Jprogramming] Sum select of a big array ?

[Anssi Sepp�l]

I am working with a rather big table ($tab is  55000 x 2000) stored 
as a mapped file. +/  tab works fine, but if I call +/ to a subset of 
too many elements it is out of memory (like +/ (I. x) {tab, +/ 
x#tab). Is there algorithm that could do the partial sum in place or 
is there any method other than looping the calculation in J?

Anssi
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