Hi, I'm trying to implement a matrix product example using DPH. This is the code: ------------------------------------------------------------------------------------------------------------------- type MMultType = Double type Matrix = [:[:MMultType:]:] type MVector = [:MMultType:] type Matrix_wrapper = PArray (PArray MMultType) {-# NOINLINE matMult_wrapper #-} matMult_wrapper :: Matrix_wrapper -> Matrix_wrapper -> Matrix_wrapper matMult_wrapper mA mB = toPArrayP (mapP toPArrayP (matMult (fromNestedPArrayP mA) (fromNestedPArrayP mB))) matMult :: Matrix -> Matrix -> Matrix matMult mA mB = mapP (\row -> mapP (\col -> dotp row col) (transposeP mB)) mA dotp :: MVector -> MVector -> MMultType dotp row col = D.sumP (zipWithP (D.*) row col) transposeP :: Matrix -> Matrix transposeP m = let h = lengthP m w = lengthP (m !: 0) rh = I.enumFromToP 0 (h I.- 1) rw = I.enumFromToP 0 (w I.- 1) in if h I.== 0 then [: :] else mapP (\y -> mapP (\x -> m !: x !: y) rh) rw ------------------------------------------------------------------------------------------------------------------- My problem is at execution time, on matrices of size 300*300 the program does finish (although it is very slow), but on 700*700 it consumes GBs of RAM until the process is aborted. In the paper "Work Efficient Higher-Order Vectorisation" it is explained that a work complexity problem (wich involved unnecesary array replication) was recently treated. So at first I thought the code implementation related to the paper had not been uploaded to hackage. But as I understand it must have been, as that seems to be the motive of the "dph-lifted-vseg" package. Does anybody notice the problem with the example or if the problem is related to the subject treated in the paper? Thanks in advance!