On 26/05/2011 14:32, michael rice wrote:
Fair question. I copied the parallel version from:
<http://www.haskell.org/ghc/docs/6.6/html/users_guide/lang-parallel.html>
http://www.haskell.org/ghc/docs/6.6/html/users_guide/lang-parallel.html
That is the User Guide for GHC 6.6, incidentally. If you're using a
later version of GHC (highly recommended especially for parallel stuff),
then you should look at the docs for your version.
Cheers,
Simon
<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]
</mc/[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 -> 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 ~]$
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