"Rafael Almeida"
[perfect square problem]
most of this is shamelessly stolen from http://www.haskell.org/haskellwiki/Generic_number_type#squareRoot (^!) :: Num a => a -> Int -> a (^!) x n = x^n isSquare :: Integer -> Bool isSquare n = let newtonStep x = div (x + div n x) 2 iters = iterate newtonStep $ truncate $ sqrt $ fromIntegral n isRoot r = r^!2 <= n && n < (r+1)^!2 root = head $ dropWhile (not . isRoot) iters in root^!2 == n *Main> isSquare (2^1024) True *Main> isSquare (2^1024+1) False *Main> isSquare (2^1024-1) False *Main> isSquare (2^2^16) True the last one take a bit less than 20 secs on my pc. And 2^2^16 is a number that takes at least an hour to pronounce. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited.