文責: | @naoiwata |
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フィボナッチ数列の以下の式を考える.
(fixed-point
(lambda (x) (+ 1 (/ 1 x)))
1.0))
;; => 1.6180327868852458
(define (close-enough? x y)
(< (abs (- x y)) 0.001))
(define tolerance 0.00001)
(define (fixed-point f first-guess)
(define (close-enough? v1 v2)
(< (abs (- v1 v2)) tolerance))
(define (try guess)
(let ((next (f guess)))
(if (close-enough? guess next)
next
(try next))))
(try first-guess))
(fixed-point
(lambda (x) (+ 1 (/ 1 x)))
1.0)
;; => 1.6180327868852458