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 wrote:
From: David Virebayre
Subject: Re: [Haskell-cafe] Parallel compilation and execution?
To: "michael rice"
Cc: haskell-cafe@haskell.org, "Daniel Fischer"
Date: Thursday, May 26, 2011, 8:56 AM
2011/5/26 michael rice
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 ~]$
