Opened 6 years ago
Closed 3 years ago
#17251 closed defect (fixed)
Incomplete multivariate factorization
Reported by:  jdemeyer  Owned by:  

Priority:  critical  Milestone:  sage8.2 
Component:  factorization  Keywords:  singular 
Cc:  jakobkroeker  Merged in:  
Authors:  Frédéric Chapoton  Reviewers:  Travis Scrimshaw 
Report Upstream:  Completely fixed; Fix reported upstream  Work issues:  
Branch:  8ce76ba (Commits)  Commit:  8ce76ba086323151cbbd4227d51340749cb7ff2f 
Dependencies:  Stopgaps: 
Description (last modified by )
With sage6.4.beta6, the following polynomial factorization gives a reducible factor (a^2 + b^2)
:
sage: R.<z,a,b> = PolynomialRing(QQ) sage: N = a^4*z^8 + 2*a^2*b^2*z^8  b^4*z^8  16*a^3*b*z^7 + 16*a*b^3*z^7 + 28*a^4*z^6  56*a^2*b^2*z^6 + 28*b^4*z^6 + 112*a^3*b*z^5  112*a*b^3*z^5  70*a^4*z^4 + 140*a^2*b^2*z^4  70*b^4*z^4  112*a^3*b*z^3 + 112*a*b^3*z^3 + 28*a^4*z^2  56*a^2*b^2*z^2 + 28*b^4*z^2 + 16*a^3*b*z  16*a*b^3*z  a^4 + 2*a^2*b^2  b^4 sage: N.factor() (1) * (a^2 + b^2) * (z^4*a + z^4*b  4*z^3*a  4*z^3*b + 6*z^2*a  6*z^2*b + 4*z*a + 4*z*b  a + b) * (z^4*a + z^4*b  4*z^3*a + 4*z^3*b  6*z^2*a  6*z^2*b + 4*z*a  4*z*b + a + b)
This is fixed by #17254.
Change History (9)
comment:1 Changed 6 years ago by
 Keywords singular added
comment:2 Changed 6 years ago by
 Description modified (diff)
comment:3 Changed 6 years ago by
 Description modified (diff)
 Report Upstream changed from N/A to Completely fixed; Fix reported upstream
comment:4 Changed 6 years ago by
 Dependencies set to #17254
comment:5 Changed 4 years ago by
 Cc jakobkroeker added
comment:6 Changed 3 years ago by
 Branch set to u/chapoton/17251
 Commit set to 8ce76ba086323151cbbd4227d51340749cb7ff2f
 Dependencies #17254 deleted
 Status changed from new to needs_review
New commits:
8ce76ba  trac 17251 adding a doctest for factorisation of polynomials

comment:7 Changed 3 years ago by
 Milestone changed from sage6.4 to sage8.2
comment:8 Changed 3 years ago by
 Reviewers set to Travis Scrimshaw
 Status changed from needs_review to positive_review
LGTM.
comment:9 Changed 3 years ago by
 Branch changed from u/chapoton/17251 to 8ce76ba086323151cbbd4227d51340749cb7ff2f
 Resolution set to fixed
 Status changed from positive_review to closed
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