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

(defn good-enough? [previous current]
  (>=
    (* current 0.001)
    (math/abs (- current previous))))

(defn average [x y]
  (/ (+ x y) 2))

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

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

(defn sqrt [x]
  (sqrt-iter 0.0 x x))

(var i 0.0000001)
(while (<= i 1000000000000.0)
  (def meas (sqrt i))
  (def rel (/ (- meas (math/sqrt i)) meas))
  (print (string/format "Relative error %f=%f, %f" (math/sqrt i) meas rel))
  (set i (* i 3.141519)))