Mantissa.hs

import Control.Monad.State.Lazy
import Text.Printf

aprox :: Double -> State Double Double
aprox t = state (\y -> 
  let add = (t - x) * (1.0 - y) / (10.0 - x)
      x = 10.0 ** y
  in (t - x, y + add))

combine_x_times :: (Monad m) => Int -> m a -> m a
combine_x_times 1 m = m
combine_x_times n m = (combine_x_times (n - 1) m) >> m

get_mantissa :: Int -> Int
get_mantissa n = round $
    10000 * (execState (combine_x_times 50 $ aprox asFrac) 0.00)
  where
    asFrac = fromIntegral n / 100.0

printColumn :: Int -> Int -> IO ()
printColumn _ 0 = return ()
printColumn n i = do
    if odd n then printf "%04d" (get_mantissa n)
             else printf "\x1b[7m%04d\x1b[m" (get_mantissa n)
    printColumn (n + 1) (i - 1)

printRows :: Int -> IO ()
printRows 100 = return ()
printRows r = do
    printf "%02d " r
    printColumn (r * 10) 10
    putStrLn ""
    printRows $ r + 1

main :: IO ()
main = printRows 10