project2.hs

main :: IO ()
main = mapM_ (print . abs . ((cos x) -) . (myCosTaylor x)) [1 .. 100]
        where x = 30

fac :: Integral a => a -> a
fac 0 = 1
fac n = fac (n-1) * n

a :: Integral a => Double -> a -> Double
a x i = if odd i
            then - x ^ (2 * i) / (fromIntegral . fac) (2 * i)
            else x ^ (2 * i) / (fromIntegral . fac) (2 * i)

myCosTaylor :: Integral a => Double -> a -> Double
myCosTaylor x n = sum $ take (fromIntegral n) (map (a x) [0..])