/usr/share/scsh-0.6/rts/ratnum.scm is in scsh-common-0.6 0.6.7-8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | ; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
; This is file ratnum.scm.
; Rational arithmetic
; Assumes that +, -, etc. perform integer arithmetic.
(define-simple-type :exact-rational (:rational :exact)
(lambda (n) (and (rational? n) (exact? n))))
(define-extended-number-type :ratnum (:exact-rational :exact) ;?
(make-ratnum num den)
ratnum?
(num ratnum-numerator)
(den ratnum-denominator))
(define (integer/ m n)
(cond ((< n 0)
(integer/ (- 0 m) (- 0 n)))
((= n 0)
(error "rational division by zero" m))
((and (exact? m) (exact? n))
(let ((g (gcd m n)))
(let ((m (quotient m g))
(n (quotient n g)))
(if (= n 1)
m
(make-ratnum m n)))))
(else (/ m n)))) ;In case we get flonums
(define (rational-numerator p)
(if (ratnum? p)
(ratnum-numerator p)
(numerator p)))
(define (rational-denominator p)
(if (ratnum? p)
(ratnum-denominator p)
(denominator p)))
; a/b * c/d = a*c / b*d
(define (rational* p q)
(integer/ (* (rational-numerator p) (rational-numerator q))
(* (rational-denominator p) (rational-denominator q))))
; a/b / c/d = a*d / b*c
(define (rational/ p q)
(integer/ (* (rational-numerator p) (rational-denominator q))
(* (rational-denominator p) (rational-numerator q))))
; a/b + c/d = (a*d + b*c)/(b*d)
(define (rational+ p q)
(let ((b (rational-denominator p))
(d (rational-denominator q)))
(integer/ (+ (* (rational-numerator p) d)
(* b (rational-numerator q)))
(* b d))))
; a/b - c/d = (a*d - b*c)/(b*d)
(define (rational- p q)
(let ((b (rational-denominator p))
(d (rational-denominator q)))
(integer/ (- (* (rational-numerator p) d)
(* b (rational-numerator q)))
(* b d))))
; a/b < c/d when a*d < b*c
(define (rational< p q)
(< (* (rational-numerator p) (rational-denominator q))
(* (rational-denominator p) (rational-numerator q))))
; a/b = c/d when a = b and c = d (always lowest terms)
(define (rational= p q)
(and (= (rational-numerator p) (rational-numerator q))
(= (rational-denominator p) (rational-denominator q))))
; (rational-truncate p) = integer of largest magnitude <= (abs p)
(define (rational-truncate p)
(quotient (rational-numerator p) (rational-denominator p)))
; (floor p) = greatest integer <= p
(define (rational-floor p)
(let* ((n (numerator p))
(q (quotient n (denominator p))))
(if (>= n 0)
q
(- q 1))))
; Extend the generic number procedures
(define-method &rational? ((n :ratnum)) #t)
(define-method &numerator ((n :ratnum)) (ratnum-numerator n))
(define-method &denominator ((n :ratnum)) (ratnum-denominator n))
(define-method &exact? ((n :ratnum)) #t)
;(define-method &exact->inexact ((n :ratnum))
; (/ (exact->inexact (numerator n))
; (exact->inexact (denominator n))))
;(define-method &inexact->exact ((n :rational)) ;?
; (/ (inexact->exact (numerator n))
; (inexact->exact (denominator n))))
(define-method &/ ((m :exact-integer) (n :exact-integer))
(integer/ m n))
(define (define-ratnum-method mtable proc)
(define-method mtable ((m :ratnum) (n :exact-rational)) (proc m n))
(define-method mtable ((m :exact-rational) (n :ratnum)) (proc m n)))
(define-ratnum-method &+ rational+)
(define-ratnum-method &- rational-)
(define-ratnum-method &* rational*)
(define-ratnum-method &/ rational/)
(define-ratnum-method &= rational=)
(define-ratnum-method &< rational<)
(define-method &floor ((m :ratnum)) (rational-floor m))
;(define-method &sqrt ((p :ratnum))
; (if (< p 0)
; (next-method)
; (integer/ (sqrt (numerator p))
; (sqrt (denominator p)))))
(define-method &number->string ((p :ratnum) radix)
(string-append (number->string (ratnum-numerator p) radix)
"/"
(number->string (ratnum-denominator p) radix)))
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