Heron-sqrt.scm

#; Heron's algorithm of calculating a square root
#; https://www.youtube.com/watch?v=XYKRVNQ_MqE
(define (abs x) 
    (if (< x 0) (- x) x))

(define (average x y) 
    (/ (+ x y) 2))

(define (improve guess x)
    (average guess (/ x guess)))

(define (good-enough? guess x) 
    (< (abs (- (square guess) x)) .001))

(define (try guess x)
    (if (good-enough? guess x)
        guess
        (try (improve guess x) x)))
        
(define (sqrt x) (try 1 x))

(sqrt 2)
#; => 1.4142156862745097