#13770: bug in multivariate factorization over prime fields
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Reporter: zimmerma | Owner: malb
Type: defect | Status:
Priority: critical | needs_review
Component: commutative algebra | Milestone: sage-5.12
Keywords: | Resolution:
Authors: Paul Zimmermann | Merged in:
Report Upstream: Fixed upstream, but not in a | Reviewers:
stable release. | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by zimmerma):
Jeroen,
> Wouldn't it be safer to include all four commits?
indeed (maybe only the first three, since the last one only adds tests).
But I didn't know how to extract the diff, thus I edited the Singular
source file manually, it took then several hours on my laptop to recompile
the spkg and rebuild Sage, thus I was quite happy it worked (currently
running
sage -t --long).
> Did you check whether this solves #14658?
unfortunately not. The first example of #14658 does no longer produce an
error (same with vanilla 5.11 btw) but the factorization is incomplete:
{{{
sage: R.<x1,x2,x3> = QQ['x1,x2,x3']
sage: f = (x1+x2+x3)*(2*x1-x2+x3+2)*(4*x1+x2+x3+2)*(8*x1-x2+x3+4)
sage: f.factor()
(x1 + x2 + x3) * (64*x1^3 - 24*x1^2*x2 - 6*x1*x2^2 + x2^3 + 56*x1^2*x3 -
8*x1*x2*x3 - x2^2*x3 + 14*x1*x3^2 - x2*x3^2 + x3^3 + 128*x1^2 - 20*x1*x2 -
4*x2^2 + 68*x1*x3 - 4*x2*x3 + 8*x3^2 + 80*x1 - 4*x2 + 20*x3 + 16)
}}}
The other example still breaks with {{{Floating point exception}}}.
Paul
--
Ticket URL: <http://trac.sagemath.org/ticket/13770#comment:14>
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