73 lines
2.1 KiB
Scheme
Executable File
73 lines
2.1 KiB
Scheme
Executable File
#!/usr/bin/env ikarus --r6rs-script
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(import (ikarus))
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#;
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(define (rationalize x eps)
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(define who 'rationalize)
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(define (simplest x y)
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(cond
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[(< y x) (simplest y x)]
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[(= x y) x]
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[(> x 0)
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(let ([n (numerator x)] [d (denominator x)]
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[n^ (numerator y)] [d^ (denominator y)])
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(simplest^ n d n^ d^))]
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[(< y 0)
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(let ([n (numerator x)] [d (denominator x)]
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[n^ (numerator y)] [d^ (denominator y)])
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(- (simplest^ (- n^) d^ (- n) d)))]
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[else 1]))
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(define (simplest^ n d n^ d^)
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(let-values ([(q r) (quotient+remainder n d)])
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(if (= r 0)
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q
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(let-values ([(q^ r^) (quotient+remainder n^ d^)])
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(if (= q q^)
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(let ([v (simplest^ d^ r^ d r)])
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(let ([n^^ (numerator v)] [d^^ (denominator v)])
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(/ (+ (* q n^^) d^^) n^^)))
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(+ q 1))))))
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(define (go x eps)
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(simplest (- x eps) (+ x eps)))
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(cond
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[(flonum? x)
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(if (flfinite? x)
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(cond
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[(flonum? eps)
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(if (flfinite? eps) (go x eps) +nan.0)]
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[(or (fixnum? eps) (bignum? eps) (ratnum? eps))
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(go x eps)]
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[else (error who "~s is not a number" eps)])
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(cond
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[(flonum? eps)
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(if (flfinite? eps) x +nan.0)]
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[(or (fixnum? eps) (bignum? eps) (ratnum? eps))
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x]
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[else (error who "~s is not a number" eps)]))]
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[(or (fixnum? x) (bignum? x) (ratnum? x))
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(cond
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[(flonum? eps)
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(if (flfinite? eps) (go x eps) +nan.0)]
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[(or (fixnum? eps) (bignum? eps) (ratnum? eps))
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(go x eps)]
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[else (error who "~s is not a number" eps)])]
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[else (error who "~s is not a number" x)]))
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(define (test v0 v1 r)
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(let ([s (time (rationalize v0 v1))])
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(unless (or (= s r) (and (flnan? s) (flnan? r)))
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(error 'test "failed in ~s ~s => ~s, should be ~s"
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v0 v1 s r))))
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(test 314/100 1/100 22/7)
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(test #e0.3 1/10 1/3)
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(test 0.3 1/10 #i1/3)
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(test +inf.0 3 +inf.0)
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(test +inf.0 +inf.0 +nan.0)
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