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User talk:Gaaijz: Difference between revisions
→Miller Rabin: 946 prime?
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[[User:DanBron|DanBron]] 13:48, 2 September 2008 (UTC)
== Zigzag ==
Two different approaches with Haskell for the zigzag task.
zigzag m n = take m .transp_wof $ zipWith id (cycle [reverse,id]) antiDiags where
mmn = min m n
antiDiags = unfoldr (\((c:cs),xs) -> if null xs then Nothing else Just (take c xs,(cs,drop c xs)))
([1..mmn-1]++(replicate (succ.abs $ m-n) mmn)++[mmn-1,mmn-2..0], [0..m*n-1])
transp_wof = unfoldr (\xs -> if null xs then Nothing else Just $ next xs)
next xs = (,) (concatMap (take 1) ks) ((map (drop 1) $ drop 1 ks) ++ ts)
where (ks,ts) = splitAt n xs
:Slower version, almost complete emulation of the J-solution
groupon f x y= f x == f y
tab n = fst . until (null.snd) (\(xs,ys)-> (xs++[take n ys], drop n ys)) . (,) []
grade xs = map snd. sort $ zip xs [0..]
zigzagJ m n = tab n. grade .concat $ zipWith id (cycle [reverse,id]) fdiag
where fdiag = map (map snd). groupBy (groupon fst).sortBy (comparing fst)
$ zip (map sum $ sequence [[0..m-1],[0..n-1]] ) [0..]
*Main> sum.map sum $ zigzag 500 500
1185103928
(0.69 secs, 103908376 bytes)
*Main> sum.map sum $ zigzagJ 500 500
31249875000
(4.55 secs, 575802084 bytes)
== Words Of Equal Characters ==
Hi, Could you add some sample output to your Haskell implementation? Thanks. --[[User:Paddy3118|Paddy3118]] 18:47, 26 September 2008 (UTC)
== [[Generic swap]] ==
Hello again. I've [http://rosettacode.org/w/index.php?title=User_talk%3ADanBron&diff=17957&oldid=17947 responded] to your [http://rosettacode.org/w/index.php?title=User_talk%3ADanBron&diff=17947&oldid=17600 question] re: [[Generic swap]].
--[[User:DanBron|DanBron]] 16:05, 29 September 2008 (UTC)
== [[User_talk:DanBron#J_alphabet_gaps|J alphabet gaps]] ==
Hey. I've [http://rosettacode.org/w/index.php?title=User_talk:DanBron&diff=21027&oldid=20969 responded] to your [http://rosettacode.org/w/index.php?title=User_talk:DanBron&diff=20969&oldid=17957 inquiry] about alphabetic gaps in J's task coverage on RC.
--[[User:DanBron|DanBron]] 20:26, 23 January 2009 (UTC)
==Miller Rabin: 946 prime?==
Hi Gaaijz, I was doing the left truncatable prime task and started by improving the Miller Rabin primality test for Python after finding what turns out to be one of the references you cite on your [[Miller-Rabin_primality_test#Haskell|Haskell version]]. On testing 901 to 1000 for primality in my Python I noticed that the Haskell version says 946 is prime on the page? I checked the page history and found that you had the 946 from the beginning - i.e. it is not a malicious edit so I thought I'd give you a chance to look into the Haskell code rather than me just removing the 946 from your output, which was my first thought. --[[User:Paddy3118|Paddy3118]] ([[User talk:Paddy3118|talk]]) 05:36, 23 July 2013 (UTC)
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