#7097: bug in polynomial factorization over number fields
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Reporter: cremona | Owner: tbd
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-4.3
Component: algebra | Keywords:
polynomial factor root number field
Work_issues: | Author:
John Cremona
Upstream: Fixed upstream, but not in a stable release. | Reviewer:
Merged: |
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Changes (by newvalueoldvalue):
* status: needs_work => needs_review
* upstream: => Fixed upstream, but not in a stable release.
* author: => John Cremona
Comment:
The patch seems to fix the problem by rescaling the polynomial so that it
is monic (and rescaling the factors found later).
I am somewhat confused since the code already made polynomials monic (by
dividing by the leading coefficient). Instead, I replace f(x) by
u**(d-1)*f(x/u) where u is the leading coefficient and d the degree, which
preserves integrality, and that seems to work better.
We should still use factornf instead, once we upgrade the pari library to
a version in which the upstream bug has been fixed.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7097#comment:7>
Sage <http://www.sagemath.org>
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