On Fri, Jun 27, 2003 at 12:10:55PM -0500, Shawn P. Garbett wrote:
> - --------------------------------------
> New Haskell version with Unboxed Array
> Note:it was a simple change of import and type
> - -----------------------------------------
> import Data.Array.Unboxed
>
> a :: UArray Int Int
> a = array (0,15) [(i, i) | i <- [0 .. 15] ]
>
> acc :: Int -> Int -> Int
> acc s 0 = s
> acc s n = acc (s + (a ! (n `mod` 16))) (n-1)
>
> main :: IO ()
> main = do
> print $ acc 0 100000000
I'd be curious to see timing on the following:
import Data.Array.Unboxed
import Data.Bits
a :: UArray Int Int
a = array (0,15) [(i, i) | i <- [0 .. 15] ]
acc :: Int -> Int -> Int
acc s 0 = s
acc s n = acc (s + (a ! (n .&. 15))) (n-1)
main :: IO ()
main = do
print $ acc 0 100000000
All I've done eliminated the mod call in favor of a bitwise and. I would
hope that the C compiler would do that, at least if it gives any
improvement.
--
David Roundy
http://civet.berkeley.edu/droundy/
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