Opened 11 years ago
Closed 11 years ago
#10279 closed defect (fixed)
Bug in factor of polynomials over number fields
Reported by: | lftabera | Owned by: | davidloeffler |
---|---|---|---|
Priority: | major | Milestone: | sage-4.6.2 |
Component: | number fields | Keywords: | pari, factor, number field |
Cc: | jdemeyer | Merged in: | sage-4.6.2.alpha2 |
Authors: | Jeroen Demeyer | Reviewers: | Luis Felipe Tabera Alonso |
Report Upstream: | Fixed upstream, but not in a stable release. | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
Bug raised in sage-devel by Niels Lubbes
sage: R = PolynomialRing( QQ, var( 't' ), order = 'lex' ) sage: t = R.gens()[0] sage: f = t^4 - t^2 + 1 sage: T = NumberFieldTower( [f], 'a0' ) sage: R1 = R.change_ring( T ) sage: a0 = T.gens()[0] sage: t = R1.gens()[0] sage: poly = t^3 + (-4*a0^3 + 2*a0)*t^2 - 11/3*a0^2*t + 2/3*a0^3 - 4/3*a0 sage: poly.factor() (t - 2*a0^3 + a0) * (t^2 + (-2*a0^3 + a0)*t - 2/3*a0^2) sage: fact = poly.factor()[1][0] sage: fact.factor() (t - 4/3*a0^3 + 2/3*a0) * (t - 2/3*a0^3 + 1/3*a0)
As Jeroen Demeyer points, it is a bug in Pari.
gp> t; nf = nfinit(a^4 - a^2 + 1); gp> poly = t^3 + (-4*a^3 + 2*a)*t^2 - 11/3*a^2*t + 2/3*a^3 - 4/3*a %1 = t^3 + (-4*a^3 + 2*a)*t^2 - 11/3*a^2*t + (2/3*a^3 - 4/3*a) gp> F = nffactor(nf, poly) %2 = [t + Mod(-2*a^3 + a, a^4 - a^2 + 1) 1] [t^2 + Mod(-2*a^3 + a, a^4 - a^2 + 1)*t + Mod(-2/3*a^2, a^4 - a^2 + 1) 1] gp> nffactor(nf, F[2,1]) %3 = [t + Mod(-4/3*a^3 + 2/3*a, a^4 - a^2 + 1) 1] [t + Mod(-2/3*a^3 + 1/3*a, a^4 - a^2 + 1) 1]
The fix for this bug is in #10430, the attached patch simply adds a doctest.
Attachments (1)
Change History (13)
comment:1 Changed 11 years ago by
comment:2 Changed 11 years ago by
- Cc jdemeyer added
- Component changed from factorization to number fields
- Milestone set to sage-4.6.1
- Owner changed from tbd to davidloeffler
- Report Upstream changed from Reported upstream. Little or no feedback. to Reported upstream. Developers acknowledge bug.
comment:3 Changed 11 years ago by
- Report Upstream changed from Reported upstream. Developers acknowledge bug. to Fixed upstream, but not in a stable release.
comment:4 Changed 11 years ago by
- Milestone changed from sage-4.6.1 to sage-duplicate/invalid/wontfix
- Status changed from new to needs_review
See #10430
comment:5 follow-up: ↓ 6 Changed 11 years ago by
- Milestone changed from sage-duplicate/invalid/wontfix to sage-4.6.2
I suggest we keep this ticket open until the new Pari is in, and then we can add a doctest to prove that it is fixed. Otherwise there is a danger that we forget to add such a doctest and the bug reappears at a later date.
comment:6 in reply to: ↑ 5 Changed 11 years ago by
- Description modified (diff)
Replying to davidloeffler:
I suggest we keep this ticket open until the new Pari is in, and then we can add a doctest to prove that it is fixed. Otherwise there is a danger that we forget to add such a doctest and the bug reappears at a later date.
Agreed!
comment:7 Changed 11 years ago by
- Reviewers set to Luis Felipe Tabera Alonso
- Status changed from needs_review to positive_review
This is a trivial doctest patch. The patch applies cleanly and adds a relevant doctest. Once #10430 is merged this will go along. Positive review.
comment:8 Changed 11 years ago by
- Merged in set to sage-4.6.2.alpha1
- Resolution set to fixed
- Status changed from positive_review to closed
comment:9 Changed 11 years ago by
- Merged in sage-4.6.2.alpha1 deleted
- Resolution fixed deleted
- Status changed from closed to new
comment:10 Changed 11 years ago by
- Status changed from new to needs_review
comment:11 Changed 11 years ago by
- Status changed from needs_review to positive_review
Changed 11 years ago by
comment:12 Changed 11 years ago by
- Merged in set to sage-4.6.2.alpha2
- Resolution set to fixed
- Status changed from positive_review to closed
upstream bug reference
http://pari.math.u-bordeaux.fr/cgi-bin/bugreport.cgi?bug=1132