Additional method "matrix" / "_matrix_" for the element class of ClassicalMatrixLieAlgebra

[soehms]

A method to obtain the underlying matrix as element of the corresponding full matrix space analog to the similar method of MatrixGroupElement_generic should be added. This may be a shortcut for the following:

sage: LM = lie_algebras.sp(QQ, 4, representation='matrix')
sage: e1, e2, f1, f2, h1, h2 = LM.gens()
sage: mh1 = LM.associative_algebra()(dict(h1)); mh1
[ 1  0  0  0]
[ 0 -1  0  0]
[ 0  0 -1  0]
[ 0  0  0  1]
sage: mh1.parent()
Full MatrixSpace of 4 by 4 sparse matrices over Rational Field

CC: @tscrim

Component: algebra

Keywords: classical lie algebra matrix matrix

Author: Sebastian Oehms

Branch/Commit: f1d16d1

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/25008

[soehms]

Branch: u/soehms/matrix_method-25008

[sagetrac-git]

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

089091a

simplification

[sagetrac-git]

Commit: 089091a

[tscrim]

Changed commit from 089091a to f1d16d1

[tscrim]

comment:4

I made a few small fixes to the documentation and added another test. If my changes look good, then you can set a positive review.

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New commits:

f1d16d1

Small doc tweaks and adding another test.

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

Changed branch from u/soehms/matrix_method-25008 to public/lie_algebras/matrix_method-25008

[vbraun]

Changed branch from public/lie_algebras/matrix_method-25008 to f1d16d1