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Edit detail for #405 ContinuedFraction and Polynomial Domains revision 3 of 7

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Editor: page
Time: 2007/12/12 14:17:18 GMT-8
Note: Specify version of Axiom

added:

From page Wed Dec 12 14:17:18 -0800 2007
From: page
Date: Wed, 12 Dec 2007 14:17:18 -0800
Subject: Specify version of Axiom
Message-ID: <20071212141718-0800@axiom-wiki.newsynthesis.org>

Axiom Version:  => friCAS-20071109 


Submitted by : kratt6 at: 2007-12-05T06:41:43-08:00 (16 years ago)
Name :
Axiom Version :
Category : Severity : Status :
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Consider

axiom
d := continuedFraction(0,[1 for i in 1..], [1 for i in 0..])$CONTFRAC INT
LatexWiki Image(1)
Type: ContinuedFraction? Integer
axiom
2*d
LatexWiki Image(2)
Type: ContinuedFraction? Integer

so far, so good. But changing the domain to CONTFRAC UP(x, FRAC INT) makes axiom crash.

The problem appears to be, that INT is ordered, while UP(x, FRAC INT) is not. In contfrac.spad we find:

    eucWhole(a: Q): R == numer a quo denom a

    eucWhole0(a: Q): R ==
        isOrdered =>
            n := numer a
            d := denom a
            q := n quo d
            r := n - q*d
            if r < 0 then q := q - 1
            q
        eucWhole a

If R is INT, eucWhole0(4/3) yields 1, in the other case it returns 4/3. I haven't been able to investigate further yet, though.

Martin

Specify version of Axiom --page, Wed, 12 Dec 2007 14:17:18 -0800 reply
Axiom Version: => friCAS-20071109