#17658: Incorrect densification of polynomial matrix
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Reporter: gagern | Owner:
Type: defect | Status: new
Priority: critical | Milestone: sage-6.5
Component: linear algebra | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by gagern):
Replying to [comment:1 pbruin]:
> I wonder if there could be any link with #17527.
I doubt it. `loads(dumps(m))` works in my case. One thing which appears to
be a factor here is the fact that `i.degrees()` returns an `ETuple`.
{{{
sage: R1.<a,b> = QQ[]
sage: m = matrix({ETuple((0, 1)): b, ETuple((1, 0)): a})
sage: m.dense_matrix()
[0 0]
[0 0]
}}}
But the underlying ring plays a role as well. Particularly,
`Matrix_generic_sparse` seems to be affected while `Matrix_integer_sparse`
or `Matrix_modn_sparse` are not. Other things which are handled by the
generic implementation suffer as well:
{{{
sage: matrix(GF(5^2,"z"),{ETuple((1, 1)): 2}).dense_matrix()
[0 0]
[0 0]
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/17658#comment:2>
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