Problem 197

197 Investigating the behaviour of a recursively defined sequence

Problem 197 – Project Euler

どうせ循環するのだろうと思い,はじめの1000項をgnuplotでプロット.

f:id:jeneshicc:20090208221740p:image

実はすぐに,収束していた.

収束のしかたが単純.

f :: Double -> Double
f x = let a = 30.403243784
y = a - x^2
in 1E-9 * fromIntegral (floor $ 2 ** y)
p197 :: Double
p197 = loop.iterate f $ (-1)
where loop (a:b:c:ds) | a == c    = a+b
| otherwise = loop $ c:ds
--main = putStrLn.unlines.map show.take 1000 $ us
More Reading
Newer// Problem 196
Older// Problem 195