From: michael rice <nowgate@yahoo.com>
Subject: Re: [Haskell-cafe] Parallel compilation and execution?
To: "David Virebayre" <dav.vire+haskell@gmail.com>
Cc: "Daniel Fischer" <daniel.is.fischer@googlemail.com>, haskell-cafe@haskell.org
Date: Thursday, May 26, 2011, 9:32 AM

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 <dav.vire+haskell@gmail.com> wrote: From: David Virebayre <dav.vire+haskell@gmail.com> Subject: Re: [Haskell-cafe] Parallel compilation and execution? To: "michael rice" <nowgate@yahoo.com> Cc: haskell-cafe@haskell.org, "Daniel Fischer" <daniel.is.fischer@googlemail.com> Date: Thursday, May 26, 2011, 8:56 AM 2011/5/26 michael rice <nowgate@yahoo.com> 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 -> Int nfib 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 -N3 204668309 [michael@hostname ~]$ ghc --make nfib.hs [1 of 1] Compiling Main             ( nfib.hs, nfib.o ) Linking nfib ... [michael@hostname ~]$ ./nfib 102334155 [michael@hostname ~]$

-----Inline Attachment Follows-----

_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe