#11316: Weighted degree term orders added
--------------------------------+-------------------------------------------
Reporter: klee | Owner: AlexGhitza
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.7.1
Component: basic arithmetic | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: Kwankyu Lee
Merged: | Dependencies:
--------------------------------+-------------------------------------------
Changes (by SimonKing):
* status: needs_work => needs_review
* work_issues: Singular conversion with negative degree weights =>
Comment:
... and the reason for the error is that the the string representation of
polynomials does not correctly deal with polynomials of negative degree:
{{{
sage: str(N.gens())
'(0*a, 0*b, 0*c)'
}}}
That should be '(a, b, c)'.
Looking at `a._repr_`, I see that in fact Singular is to blame. And
indeed, in Singular we have
{{{
> ring r = 0,(a,b,c),Wp(-1,2,-3);
> b;
0b
> ring r = 0,(a,b,c),Wp(1,2,0);
// ** redefining r **
> b;
0b
}}}
So, there is a bug in Singular that should be reported upstream.
Nevertheless, I think it should be addressed here, namely by stating in
the documentation that the weights have to be positive integral. I can do
that in a reviewer patch, if you like.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11316#comment:26>
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