using -fexcess-precision improves the runtime from about 180259 ns to 140201 ns on my environment (Intel P3, 700Mhz, 384 MB Ram, Win2k). That makes for me a speedup of 1.29. I tested the other flags, -funbox-strict-fields -fliberate-case-threshold100 but did not see an improvement. Well, pure Haskell has a runtime of
140201 ns
as stated above for a test of 9000 calls (thanks to the "sum $ map f [inputlist]" pattern!). If i use the C aibd as foreign call, i get a runtime of
80115 ns
That's pretty good (both ghc6.0.1 on MinGW windows env). But if i look at my Java or C++ solution, then Java takes for the same task (JVM 1.4.2_01 client vm)
30000 ns.
Looking at your code, it looks like you should add some more strictness. eg: 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 Some of the parameters to the inner recursive function 'sekantenIter' are lazy. Try adding some seqs to help the strictness analyser: 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 x3 `seq` y3 `seq` dy `seq` dx `seq` if (istOk gx x3 dx) && (istOk gy y3 dy) then x3 else sekantenIter f (tiefe-1) gx gy x2 x3 y2 y3 Cheers, Simon