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Shootout/Nsieve Bits - Revision history
2024-03-28T19:22:46Z
Revision history for this page on the wiki
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https://wiki.haskell.org/index.php?title=Shootout/Nsieve_Bits&diff=14373&oldid=prev
DonStewart: /* (Proposed) Fast 3 entry */
2007-07-15T15:43:22Z
<p><span dir="auto"><span class="autocomment">(Proposed) Fast 3 entry</span></span></p>
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<td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>-- http://shootout.alioth.debian.org/</div></td>
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<td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>main = do</div></td>
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<td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> n <- getArgs >>= readIO . head :: IO Int</div></td>
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<td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>sieve n = do</div></td>
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<td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> let r = runST (do a <- newArray (2,n) True :: ST s (STUArray s Int Bool)</div></td>
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<td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> go a n 2 0)</div></td>
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<td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td>
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DonStewart
https://wiki.haskell.org/index.php?title=Shootout/Nsieve_Bits&diff=6697&oldid=prev
DonStewart: moved
2006-10-08T01:53:14Z
<p>moved</p>
<p><b>New page</b></p><div><br />
A ShootoutEntry for the [http://shootout.alioth.debian.org/gp4/benchmark.php?test=nsievebits&lang=all nsieve-bits problem].<br />
<br />
Each program should count the prime numbers from 2 to M, using the same na�ve Sieve of Eratosthenes algorithm:<br />
<br />
* create an array of M bit flags<br />
* for each index number<br />
** if the flag value at that index is true<br />
j** set all the flag values at multiples of that index false<br />
*** increment the count<br />
<br />
Calculate 3 prime counts, for M = 2N � 10000, 2N-1 � 10000, and 2N-2 � 10000.<br />
<br />
== Benchmarks ==<br />
<br />
Linux/x86, N=10<br />
<br />
|| Entry || Time ||<br />
|| Fast 3 || 0.656 ||<br />
|| Fast 2 || 0.720 ||<br />
|| Fast 1 || 1.028 ||<br />
|| Original|| 1.031 ||<br />
<br />
<br />
== (Proposed) Fast 3 entry ==<br />
<br />
Careful attention to strictness ensures all args are unboxed (taking the<br />
idea from the NsieveEntry). Squeezes another 10%. This should be the 2nd<br />
or 3rd fastest entry overall -- finally beating OCaml, D and SML :)<br />
<br />
<haskell><br />
--<br />
-- The Great Computer Language Shootout<br />
-- http://shootout.alioth.debian.org/<br />
--<br />
-- Haskell Shootout entries - http://haskell.org/hawiki/ShootoutEntry<br />
-- Contributed by (c) Simon Marlow 2005<br />
-- Modified by Don Stewart<br />
--<br />
<br />
import Data.Bits; import Data.Array.IO; import Data.Array.Base<br />
import System; import IO; import Text.Printf<br />
<br />
main = (\n -> mapM_ (sieve . shiftL 10000 . (-) n) [0..2]) . read . head =<< getArgs<br />
<br />
sieve m = do r <- newArray (0,m) False >>= \(a::IOUArray Int Bool) -> for a m 2 0<br />
printf "Primes up to %8d %8d\n" (m::Int) (r::Int)<br />
<br />
for arr m i c | arr `seq` m `seq` i `seq` c `seq` False = undefined -- strict<br />
for arr m i c = if i > m then return c else do<br />
x <- unsafeRead arr i<br />
if x then for arr m (i+1) c<br />
else let for' j | j > m = for arr m (i+1) (c+1)<br />
| otherwise = unsafeWrite arr j True >> for' (j+i)<br />
in for' (i*2)<br />
</haskell><br />
<br />
== Fast 2 entry ==<br />
<br />
Short, and uses unsafe reads for realistic speed<br />
Use '''-O2 -optc-O3'''.<br />
<br />
<haskell><br />
--<br />
-- The Great Computer Language Shootout<br />
-- http://shootout.alioth.debian.org/<br />
-- Contributed by (c) Simon Marlow 2005<br />
-- Modified by Don Stewart<br />
--<br />
<br />
import Data.Bits; import Data.Array.IO; import Data.Array.Base<br />
import System; import IO; import Text.Printf<br />
<br />
main = (\n -> mapM_ (sieve.(10000 *).shiftL 1) [n,n-1,n-2]) . read . head =<< getArgs<br />
<br />
sieve m = do<br />
arr <- newArray (0,m) False :: IO (IOUArray Int Bool)<br />
let for i c<br />
| c `seq` False = undefined -- strictness hack<br />
| otherwise = if i > m then return c else do<br />
x <- unsafeRead arr i<br />
if x then for (i+1) c<br />
else let for' j | j > m = for (i+1) (c+1)<br />
| otherwise = unsafeWrite arr j True >> for' (j+i)<br />
in for' (i*2)<br />
r <- for 2 0<br />
printf "Primes up to %8d %8d\n" (m::Int) (r::Int) :: IO ()<br />
</haskell><br />
<br />
== Fast 1 entry ==<br />
<br />
Shorter, might be slightly faster too.<br />
<br />
<haskell><br />
-- The Great Computer Language Shootout<br />
-- http://shootout.alioth.debian.org/<br />
-- Contributed by (c) Simon Marlow 2005<br />
-- Modified by Don Stewart<br />
<br />
import Data.Bits; import Data.Array.IO; import System; import IO; import Text.Printf<br />
<br />
main = (\n -> mapM_ (sieve.(10000 *).shiftL 1) [n,n-1,n-2]) . read . head =<< getArgs<br />
<br />
sieve m = do<br />
arr <- newArray (0,m) False :: IO (IOUArray Int Bool)<br />
let for i c<br />
| c `seq` False = undefined -- strictness hack<br />
| otherwise = if i > m then return c else do<br />
x <- readArray arr i<br />
if x then for (i+1) c<br />
else let for' j | j > m = for (i+1) (c+1)<br />
| otherwise = writeArray arr j True >> for' (j+i)<br />
in for' (i*2)<br />
r <- for 2 0<br />
printf "Primes up to %8d %8d\n" (m::Int) (r::Int) :: IO ()<br />
</haskell><br />
<br />
== Original entry ==<br />
<br />
<haskell><br />
{-# OPTIONS -O2 -optc-O3 #-}<br />
-- The Great Computer Language Shootout<br />
-- http://shootout.alioth.debian.org/<br />
-- Contributed by (c) Simon Marlow 2005<br />
<br />
import Data.Array.IO<br />
import System<br />
import IO<br />
import Monad<br />
import Data.Bits<br />
import Text.Printf<br />
<br />
main = do<br />
as <- getArgs<br />
case as of<br />
[m] -> do let n = read m :: Int<br />
test n<br />
when (n >= 1) $ test (n-1)<br />
when (n >= 2) $ test (n-2)<br />
_ -> do hPutStrLn stderr "usage: nsieve-bits M"<br />
exitWith (ExitFailure 1)<br />
<br />
test :: Int -> IO ()<br />
test n = do<br />
let m = (1 `shiftL` n) * 10000<br />
arr <- newArray (0,m) False :: IO (IOUArray Int Bool)<br />
let for i count<br />
| count `seq` False = undefined -- strictness hack<br />
| i > m = return count<br />
| otherwise = do<br />
x <- readArray arr i<br />
if x<br />
then for (i+1) count<br />
else let for' j | j > m = for (i+1) (count+1)<br />
| otherwise = do<br />
writeArray arr j True<br />
for' (j + i)<br />
in for' (i*2)<br />
r <- for 2 0<br />
printf "Primes up to %8d %8d\n" (m::Int) (r::Int)<br />
</haskell><br />
<br />
[[Category:Code]]</div>
DonStewart