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a6.scm
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a6.scm
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"problem 1. (a)"
(define (count-positives lst)
(define (iter l count)
(cond ((= (length l) 0) count)
((> (car l) 0) (iter (cdr l) (+ count 1)))
(else (iter (cdr l) count))))
(iter lst 0))
"problem 1. (b)"
(define (multiply-list lst)
(define (iter acc l)
(if (= (length l) 0)
acc
(iter (* acc (car l)) (cdr l))))
(iter 1 lst))
"problem 1. (c)"
(define (consecutive-ints a b)
(define (iter l i)
(if (< i a)
l
(iter (cons i l) (- i 1))))
(iter (list) b))
"problem 1. (d)"
(define (consecutive-squares a b)
(define (iter l i)
(if (< i a)
l
(iter (cons (* i i) l) (- i 1))))
(iter (list) b))
"problem 2."
(define (count-if f lst)
(define (iter l count)
(cond ((= (length l) 0) count)
((f (car l)) (iter (cdr l) (+ count 1)))
(else (iter (cdr l) count))))
(iter lst 0))
"problem 3. (a)"
(define (nth-filtered f n)
(define (iter i count)
(if (f i)
(if (= count n)
i
(iter (+ i 1) (+ count 1)))
(iter (+ i 1) count )))
(iter 1 1))
"problem 3. (b)"
(define (min-value f a b)
(if (< (abs (- b a)) 0.0001)
(f a)
(let ((m (/ (+ a b) 2)))
(min (min-value f a m) (min-value f m b)))))