56 lines
1.3 KiB
Scheme
56 lines
1.3 KiB
Scheme
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(load "util.scm")
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(define (add-rat x y)
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(make-rat (+ (* (numer x) (denom y))
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(* (numer y) (denom x)))
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(* (denom x) (denom y))))
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(define (sub-rat x y)
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(make-rat (- (* (numer x) (denom y))
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(* (numer y) (denom x)))
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(* (denom x) (denom y))))
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(define (mul-rat x y)
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(make-rat (* (numer x) (numer y))
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(* (denom x) (denom y))))
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(define (div-rat x y)
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(make-rat (* (numer x) (denom y))
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(* (denom x) (numer y))))
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(define (equal-rat? x y)
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(= (* (numer x) (denom y))
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(* (numer y) (denom x))))
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(define (make-rat n d)
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(let ((g (gcd n d)))
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(cons (/ n g) (/ d g))))
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(define (numer x) (car x))
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(define (denom x) (cdr x))
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(define (print-rat x)
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(newline)
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(display (numer x))
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(display "/")
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(display (denom x)))
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; Examples
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; (define one-half (make-rat 1 2))
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; (print-rat one-half)
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; (define one-third (make-rat 1 3))
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; (print-rat (add-rat one-half one-third))
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; (print-rat (mul-rat one-half one-third))
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; (print-rat (add-rat one-third one-third))
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(display "ex-2.1")
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(define (make-rat n d)
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(let ((g (gcd n d)))
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(if (< (* n d) 0)
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(cons (- (abs (/ n g))) (abs (/ d g)))
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(cons (abs (/ n g)) (abs (/ d g))))))
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(print-rat (make-rat 3 9))
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(print-rat (make-rat -3 9))
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(print-rat (make-rat 3 -9))
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(print-rat (make-rat -3 -9))
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(display "\n\nex-2.2")
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