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scheme-code.rkt
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scheme-code.rkt
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#lang racket
(define (bitfunc x)
(+ 4
(-
(expt x 4)
(* 5
(expt x 2)))))
(define (bitfunc-rect x1 x2)
(* (- x2 x1)
(bitfunc x1)
))
(define (bitfunc-recur steps x1 x2)
(define (step) (/ (- x2 x1) steps))
(if (> steps 0)
(+ (bitfunc-rect x1 (+ x1 (step))) (bitfunc-recur (- steps 1) (+ (step) x1) x2))
0))
(define (d x) (exact->inexact x))
(define (bitfunc-iter steps x1 x2)
(define step 0)
(set! step (/ (- x2 x1) steps))
(define area 0)
(do ((n 0 (+ n 1))) ((>= n steps))
(set! area (+ area (bitfunc-rect x1 (+ x1 step))))
(set! x1 (+ x1 step))
)
(exact->inexact area))
(define (compare steps x1 x2)
(abs (- (bitfunc-recur steps x1 x2) (bitfunc-iter steps x1 x2)))
)
(define (A x y)
(cond ((= y 0) 0)
((= x 0) (* 2 y))
((= y 1) 2)
(else (A (- x 1) (A x (- y 1))))))
(define (gcd a b)
(if (= b 0)
a
(gcd b (remainder a b))))
(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))