Am Montag 01 Februar 2010 14:31:40 schrieb Markus Böhm:
Daniel, with LuaJIT it needs 1.45 sec cpu-time on my machine with attached variant.
That's pretty fast.
I compiled all our Haskell variants with ghc --make -O2.
Well, GHC isn't as good at loop-optimising as gcc is. Depending on the loop, the via-C compiled binaries are between 1.4 and 2.3 times faster than the NCG compiled.
I don't know about -fvia-C, have to find out. I hope I didn't distract You with my Lua variant.
No sweat.
In any case thank You very much for your advice. Markus.
You're welcome. Can you try the below with ghc -O2 -fexcess-precision -fvia-C -optc-O3 -o luaLoop --make Whatever.hs and run with echo '0.00000001' | time ./luaLoop ? It's a fairly direct translation of the Lua code, and it runs here more or less equally fast as (gcc compiled) C-loops. ================================= module Main (main) where main :: IO () main = do putStrLn "EPS:" eps <- readLn :: IO Double print $ 4*calcPi eps calcPi :: Double -> Double calcPi eps = go False 1 3 where go bl p1 i | 4*abs(p2-p1) < eps = p1 | otherwise = go (not bl) p2 (i+2) where p2 | bl = p1+1/i | otherwise = p1-1/i ==================================