Fibonacci Implementation

fibonacci.scm

;Recursive
(define (fib n)
  (cond ((eq? n 0) 0)
        ((eq? n 1) 1)
        (else (+ (fib (- n 2))
                 (fib (- n 1))))))

;Iterative
(define (fib n)
  (define (iter n-1 n-2 count)
    (if (< n count)
        n-1
        (iter (+ n-1 n-2) n-1 (+ 1 count))))
  (iter 1 0 0))

;What is it good for?
(define (approximate-golden-ratio n)
  (cond ((eq? n 0) 0)
        (else (exact->inexact (/ (fib (- n 1)) (fib (- n 2)))))))


(approximate-golden-ratio 30)