Code Review Notes 47.8% of your time is spent in GC. 1.5G is allocated on the heap (!) The repa code looks a lot more complicated than the list code. Lots of parallel GC is occuring I can get up to 300% efficiency on a -N4 machine Putting in more type signatures will make it … Read more
Here’s a possible modified version of your code, using delayed arrays: {-# LANGUAGE TypeOperators #-} import Data.Array.Repa as R mulM :: (Num a, Source r a) => Array r DIM2 a -> Array D DIM2 a mulM arr = traverse arr id mulM’ where mulM’ _ idx@(i’ :. i) = sumAllS $ extract (Z:.0) (Z:.(i+1)) … Read more
Most Euler numeric integration methods suffer from cumulative round-off error that will eventually cause the simulation to “blow up”. You may want to investigate advanced numerical integration methods, such as 4th-order Runge-Kutta or predictor-corrector. Another place where n-body problem simulations become sticky is when two bodies get very close, such as a moon with a … Read more
It’s been 7 years since this question has been asked, and it still seems like no-one came up with a good solution to this problem. Repa doesn’t have a mapM/traverse like function, even one that could run without parallelization. Moreover, considering the amount of progress there was in the last few years it seems unlikely … Read more