Fair question. I copied the parallel version from: http://www.haskell.org/ghc/docs/6.6/html/users_guide/lang-parallel.html but pulled the non-parallel version from a text. Michael
--- On Thu, 5/26/11, David Virebayre <[email protected]> wrote: From: David Virebayre <[email protected]> Subject: Re: [Haskell-cafe] Parallel compilation and execution? To: "michael rice" <[email protected]> Cc: [email protected], "Daniel Fischer" <[email protected]> Date: Thursday, May 26, 2011, 8:56 AM 2011/5/26 michael rice <[email protected]> Thank, Daniel Multiple threads are in evidence in my system monitor, but I wonder why I'm getting two different answers, one twice the other. The first is the parallel solution and the second is the non. Why do you add n1+n2+1 in the parallel program, but only n1+n2 in the non-parallel one ? Michael =========== {-import Control.Parallel nfib :: Int -> Intnfib n | n <= 1 = 1 | otherwise = par n1 (pseq n2 (n1 + n2 + 1)) where n1 = nfib (n-1) n2 = nfib (n-2)-} nfib :: Int -> Int nfib n | n <= 1 = 1 | otherwise = nfib (n-1) + nfib (n-2) main = do putStrLn $ show $ nfib 39 ============= [michael@hostname ~]$ ghc --make -threaded nfib.hs [1 of 1] Compiling Main ( nfib.hs, nfib.o )Linking nfib ... [michael@hostname ~]$ ./nfib +RTS -N3204668309[michael@hostname ~]$ ghc --make nfib.hs [1 of 1] Compiling Main ( nfib.hs, nfib.o )Linking nfib ...[michael@hostname ~]$ ./nfib102334155[michael@hostname ~]$
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