#13670: Inversion in polynomial quotient rings could give clearer error message
when element is non-invertible
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Reporter: Bouillaguet | Owner: malb
Type: enhancement | Status: needs_review
Priority: minor | Milestone: sage-5.5
Component: commutative algebra | Resolution:
Keywords: polynomial rings | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Charles Bouillaguet | Merged in:
Dependencies: #13671 | Stopgaps:
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Comment (by mstreng):
Replying to [comment:5 Bouillaguet]:
> Patch for the exception name. Should we fix the "zero divided by crap
equals zero" problem, while we're at it?
It's not just a problem of dividing 0 by something. If you try to compute
{{{S(2x)/S(x)}}}, then you have the same problem: the answer is non-
unique, so the univariate case gives a !ZeroDivisionError, while the
multivariate case gives the answer {{{S(2)}}} where {{{S(2+x)}}} is
equally correct.
I suppose consistency with Zmod and with the univariate case is very good,
so sure, you can fix it. I don't have an opinion on whether this ticket is
the place to do it, or whether the mailing lists need to be involved.
As for the current patch: could you remove " (and the denominator is non-
invertible)"? It makes the error message very long and does not add any
information: obviously if the denominator is invertible, then it divides
everything, including the numerator.
And can you make sure that the lines don't go over 79-characters?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13670#comment:7>
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