#18585: Comparison of sparse polynomials
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Reporter: bruno | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.9
Component: commutative | Resolution:
algebra | Merged in:
Keywords: polynomials | Reviewers: Vincent Delecroix
Authors: Bruno Grenet | Work issues:
Report Upstream: N/A | Commit:
Branch: | 3121374eed7b683bd135e9ec5086aac03c4c8eb5
u/bruno/compare_sparse_polynomials | Stopgaps:
Dependencies: |
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Comment (by vdelecroix):
Replying to [comment:17 bruno]:
> Replying to [comment:14 vdelecroix]:
> > In
> > {{{
> > if c > 0:
> > c1 = cmp(d1[k1], 0)
> > if c1: return c1
> > }}}
> > Isn't `c1` automatically nonzero? Could there be some zero
coefficients in the dictionary?
>
> {{{
> sage: R.<x> = PolynomialRing(ZZ, sparse=True)
> sage: p = R({0:1, 1:0, 2:1}, check=False)
> sage: p
> x^2 + 1
> sage: p.dict()
> {0: 1, 1: 0, 2: 1}
> }}}
> I doubt this happens often in practice, but since this is possible, I am
quite reluctant to remove the test.
Dough! I was asking because for sparse matrices it is explicitely
mentioned in the specification that no value can be zero. And this is very
useful!
--
Ticket URL: <http://trac.sagemath.org/ticket/18585#comment:18>
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