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To be fair, most white papers read by typical programmers (esp. game/gfx programmers) do not have much calculus or advanced math. Lots have sigma-notation expressions, though. In that limited context, this has some merit in aiding understanding and suggesting implementations.
Haven't read many papers in that field, but I would have expected that in most cases those sums are actually part of various matrix/vector products, not explicitly written out using sigma notation.
