#7950: factoring broken in 0 variable polynomial ring
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Reporter: burcin | Owner: malb
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.3.1
Component: commutative algebra | Keywords:
Work_issues: | Author: Burcin Erocal
Upstream: N/A | Reviewer:
Merged: |
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Changes (by was):
* status: needs_review => needs_work
Comment:
1. Factoring of 0 should raise an error like it does over ZZ, but doesn't
right now:
{{{
sage: P = PolynomialRing(ZZ,0,'')
sage: P(10).factor()
10
sage: P(0).factor()
0
sage: factor(0)
---------------------------------------------------------------------------
ArithmeticError Traceback (most recent call
last)
}}}
2. The element 10 in the polynomial ring "ZZ[]" in 0-variables is actually
*not* a unit. So it is wrong that it is put in the "unit" slot of the
factorization. Notice how factoring 10 works:
{{{
sage: R.<x> = ZZ[]
sage: (10*x).factor()
2 * 5 * x
sage: list((10*x).factor())
[(2, 1), (5, 1), (x, 1)]
}}}
In particular, the 10 is *not* treated incorrectly as a unit.
So I think this patch needs work.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7950#comment:2>
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