square_root_newton.clj

(defn average [x y] (* 0.5 (+ x y)))

(defn improve [guess x] (average guess (/ x guess)))

(defn square [x] (* x x))

(defn abs [x] (if (< 0 x) x (- 0 x)))

(defn good-enough? [guess x]
  (< (abs (- x (square guess))) 0.0000001))

(defn sqrt-iter [guess x]
  (if (good-enough? guess x) guess (sqrt-iter (improve guess x) x)))

(defn sqrt [x] (sqrt-iter 1.0 x))

(sqrt 2.0)
(sqrt 9)
(sqrt 10)