gistfile1.txt

(define (smallest-divisor n)
  (find-divisor n 2))
(define (find-divisor n test-divisor)
  (cond ((> (square test-divisor) n) n)
        ((divides? test-divisor n) test-divisor)
        (else (find-divisor n (+ test-divisor 1)))))
(define (divides? a b)
  (= (remainder b a) 0))


(define (prime? n)
  (= n (smallest-divisor n)))


(define (timed-prime-test n)
  (newline)
  (display n)
  (start-prime-test n (runtime)))

(define (start-prime-test n start-time)
  (if (prime? n)
      (report-prime (- (runtime) start-time))))

(define (report-prime elapsed-time)
  (display " *** ")
  (display elapsed-time)
  elapsed-time
)


(define (search-for-primes start end)
  (define (iter n)
    (timed-prime-test n)
    (cond ((< n end) (iter (+ 2 n)))
          (else n)
    )
  )

  (iter (if (even? start) (+ 1 start) start))
)


(define (timed-test f)
  (define (inner start-time)
    (display (f))
    (newline)
    (display (- (runtime) start-time))
  )
  (inner (runtime))
)

(define (void-find-primes)
  (define (iter current max counter)
    (if (< current max)
      (iter (+ 1 current) max (if (prime? current) (+ 1 counter) counter))
      counter
    )
  )

  (iter 2 (* 1000 200) 0)
)


(timed-test void-find-primes)