Hello frederic, Friday, July 28, 2006, 10:44:51 AM, you wrote:
much slower than the C version. I would be very grateful if someone cared to explain why this is unefficient and how to make it faster
update :: STUArray s (Int, Int) Double -> Int -> Int -> Int -> ST s () update arr i j k = do aij <- readArray arr (i, j) try update arr i j k | arr `seq` i `seq` j `seq` k `seq` True = do aij <- readArray arr (i, j) and make the same changes in other update functions. we has http://haskell.org/haskellwiki/Performance page, you should read it second problem is bounds checking in readArray. if you want better speed, you should use unsafeRead/unsafeWrite and compute index with something like (i*count+j) btw, 'newArray ((0, 0), (10, 10))' creates array with 121 elements. is this what you really need? also, "foreach=flip mapM_" will be useful for you. i also recommend you to read http://haskell.org/haskellwiki/IO_inside - ST monad differs from IO one only in what its operations are restricted to array/reference ones -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com