#10714: Rows of a zero-row sparse matrix are incorrect
------------------------------+---------------------------------------------
Reporter: rbeezer | Owner: jason, was
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.6.2
Component: linear algebra | Keywords:
Author: Rob Beezer | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by rbeezer):
* status: needs_work => needs_review
Old description:
> Row vectors from a sparse matrix are incorrect when the matrix has zero
> rows.
>
> {{{
> sage: D = matrix(0, 2, sparse=False)
> sage: D.parent()
> Full MatrixSpace of 0 by 2 dense matrices over Integer Ring
> sage: D.nrows()
> 0
> sage: D.rows()
> []
> sage: S = matrix(0, 2, sparse=True)
> sage: S.parent()
> Full MatrixSpace of 0 by 2 sparse matrices over Integer Ring
> sage: S.nrows()
> 0
> sage: S.rows()
> [(0, 0)]
> }}}
>
> `sage/matrix/matrix1.Matrix.sparse_rows()` is the place to look.
New description:
Row vectors from a sparse matrix are incorrect when the matrix has zero
rows.
{{{
sage: D = matrix(0, 2, sparse=False)
sage: D.parent()
Full MatrixSpace of 0 by 2 dense matrices over Integer Ring
sage: D.nrows()
0
sage: D.rows()
[]
sage: S = matrix(0, 2, sparse=True)
sage: S.parent()
Full MatrixSpace of 0 by 2 sparse matrices over Integer Ring
sage: S.nrows()
0
sage: S.rows()
[(0, 0)]
}}}
`sage/matrix/matrix1.Matrix.sparse_rows()` is the place to look.
Apply trac_10714-rows-sparse-matrices.patch, trac_10714-columns-sparse-
matrices.patch
--
Comment:
Isomorphic fix for columns in second patch, but apply in the order: rows
first, then columns. Which seems appropriate.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10714#comment:7>
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