Hi all, hi Seth, yes, you're right with the P4 optimizations of the MS .Net Compiler. My tests ran on a P4 1,7 GHz with 1 GB Ram. But anyway, an older C++ compiler (the 6.0 MSVC++ from... 1998?) did also better than Cygwin C++.
I haven't seen your code yet, but I have noticed in the path the Haskell is much more sensitive (compared to C++ and Java) to coding style.
Don't have to tell me, tell my colleages ;-) See, i am just trying to persuade them that using Haskell would save us a LOT of money. (And would let me finally use a language i like - the PL "nice" looks also well, though) Anyway, here comes the code. I am not using "Integer" for performance' sake. (I read about it somewhere...) Basically, this code does an iteration to do some "backward calculation" of interest rate and similar. Btw, i did not start to bother my colleages with logic programming :-) i know that this would work also. module AIBD(aibd, rechneZins, rechneRate, rechneKapital) where import Foreign(unsafePerformIO) type Funktion = Double -> Double data Genauigkeit = Absolut {wert, intervall :: Double} | Intervall Double istOk :: Genauigkeit -> Double -> Double -> Bool istOk (Absolut w i) x _ = abs (x-w) <= i istOk (Intervall i) _ dx = abs dx <= i sekantenVerfahren :: Funktion -> Genauigkeit -> Genauigkeit -> Int -> Double -> Double sekantenVerfahren f gx gy tiefe start = sekantenIter f tiefe gx gy x1 x2 y1 y2 where x1 = start x2 = start + start * 0.1 y1 = f x1 y2 = f x2 sekantenIter _ 0 _ _ _ x2 _ _ = x2 sekantenIter f tiefe gx gy x1 x2 y1 y2 = let x3 = x2 - y2 * (x2 - x1) / (y2 - y1) y3 = f x3 dy = y3 - y2 dx = x3 - x2 in if (istOk gx x3 dx) && (istOk gy y3 dy) then x3 else sekantenIter f (tiefe-1) gx gy x2 x3 y2 y3 foreign import ccall "HAIBDUtil.h caibd" caibd :: Double -> Double -> Double -> Int -> IO Double aibd:: Double -> Double -> Double -> Int -> Double aibd kapital zins rate jahre = unsafePerformIO (caibd kapital zins rate jahre) {- does the same than aibd:: Double -> Double -> Double -> Int -> Double aibd kapital _ _ 0 = kapital aibd kapital zins rate jahre = aibd (kapital + kapital * zins - rate) zins rate (jahre-1) -} rechneZins :: Double -> Double -> Int -> Double rechneZins kapital rate jahre = sekantenVerfahren f (Intervall 0.00001) (Absolut 0 0.001) 100 0.05 where f = \zins -> aibd kapital zins rate jahre rechneRate :: Double -> Double -> Int -> Double rechneRate kapital zins jahre = sekantenVerfahren f (Intervall 0.001) (Absolut 0 0.001) 100 start where start = kapital / (fromIntegral jahre) f = \rate -> aibd kapital zins rate jahre rechneKapital :: Double -> Double -> Int -> Double rechneKapital zins rate jahre = sekantenVerfahren f (Intervall 0.001) (Absolut 0 0.001) 100 start where start = rate * (fromIntegral jahre) f = \kapital -> aibd kapital zins rate jahre