;; exercises 1.46
(define (iterative-improve f enough? first-guess)
(define (iter guess)
(if (enough? guess)
guess
(iter (f guess))))
(iter first-guess))
(define (sqrt-iter-imp x)
(iterative-improve (lambda (guess) (average guess (/ x guess)))
(lambda (guess) (< (abs (- (square guess) x)) 0.001))
1.0))
(define (fixed-point-iter-imp f first-guess)
(iterative-improve f
(lambda (guess) (< (abs (- guess (f guess))) 0.001))
first-guess))
이건 내꺼
;; ex 1.46 - iterative-improve
(define (iterative-improve good? improve)
(lambda (guess)
(define (iter v)
(if (good? v)
v
(iter (improve v))))
(iter guess)))
;; sqrt
(define (sqrt-ii x)
(define (good? guess)
(< (abs (- (square guess) x)) 0.001))
(define (improve guess)
(/ (+ guess (/ x guess)) 2))
((iterative-improve good? improve) 1.0))
(sqrt-ii 9)
;; fixed-point
(define (fixed-point-ii f g)
(define (good? guess)
(< (abs (- guess (f guess)) 0.00001)))
((iterative-improve good? f) g))
(fixed-point cos 1.0)
exam10.rkt
식으로 반복될때 x가 고정점으로 수렴하면 이 고정점을 attractive fixed point라고 한다. attractive fixed point가 아니면 초기값을 잘 설정해야 한다.
