Fast Square Root Algorithm, Code in Haskell

mysqrt.hs

module Main where

-- x -> number whose sqrt has to be found
-- y -> approximate guessed sqrt of x
mysqrt x y = let z = x + y ^ 2 
	in z / (4 * y) + x * y / z

main = do
	-- lets compute sqrt(10) with guess=3
	putStr "Actual Value: "
	print $ sqrt 10
	putStr "My sqrt value, 1st iteration: "
	print $ mysqrt 10 3
	-- substitute computed value again
	putStr "My sqrt value, 2nd iteration: "
	print $ mysqrt 10 (mysqrt 10 3)
	putStrLn "Behold! They are the same" 
-- Output of this haskell program	
-- Actual Value: 3.1622776601683795
-- My sqrt value, 1st iteration: 3.162280701754386
-- My sqrt value, 2nd iteration: 3.1622776601683795
-- Behold! They are the same