mandelbrot.hs

module Main where
import Data.Complex
import Data.List
import Data.Monoid
import Data.Ratio

errorRange = 1e-20

calculate :: Complex Double -> [Double]
calculate c = map magnitude $ iterate ((+c).(^^2)) 0

divergence :: Int -> Complex Double -> Maybe Int
divergence max c =
  let targs = take max $ calculate c
  in if last targs < 2
     then Nothing
     else findIndex (getAny.((Any . isInfinite) `mappend` (Any . (>2)))) targs

step = 0.0045

plane :: [[Complex Double]]
plane = [[x :+ y | x <- [-2.0,-2.0+step..1.25]]
        | y <- [-1.5,-1.5+step..1.5]
        ]

main :: IO ()
main =
  writeFile "mandelbrot.csv" .
    intercalate "\n" .
    map (intercalate "," . map show) $ map (map (maybe 101 id . divergence 100)) plane