Implement _an_element_ for matrix spaces

[jdemeyer]

Currently, this is a bit too trivial:

sage: MatrixSpace(QQ, 3, 3).an_element()
[1 0 0]
[0 0 0]
[0 0 0]

CC: @videlec

Component: linear algebra

Author: Jeroen Demeyer

Branch/Commit: 779dffb

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/25504

[jdemeyer]

Branch: u/jdemeyer/implement__an_element__for_matrix_spaces

[sagetrac-git]

Commit: ac7cf06

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

ac7cf06

Implement `_an_element_` for matrix spaces

[jdemeyer]

comment:4

See patchbot

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

2c09211

Doctest fixes

[sagetrac-git]

Changed commit from ac7cf06 to 2c09211

[tscrim]

comment:7

If you could add a test M.density() for the sparse test to verify that it is indeed sparse (beyond the implicit test that you would kill your memory if such a sparse matrix was dense). Actually, that test makes me a bit nervous if at some point it does turn into a dense matrix. It would make it nearly impossible to debug because my computer would keep running out of memory. Perhaps it would be better to scale down the matrix and just do M.density() to show it is sparse.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

e09aed6

Implement `_an_element_` for matrix spaces

[sagetrac-git]

Changed commit from 2c09211 to e09aed6

[jdemeyer]

comment:9

I updated the branch.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

779dffb

Implement `_an_element_` for matrix spaces

[sagetrac-git]

Changed commit from e09aed6 to 779dffb

[tscrim]

comment:11

Thank you. LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[vbraun]

Changed branch from u/jdemeyer/implement__an_element__for_matrix_spaces to 779dffb