#12688: Improve documentation of span method
------------------------------+---------------------------------------------
Reporter: rbeezer | Owner: jason, was
Type: enhancement | Status: new
Priority: minor | Milestone: sage-5.0
Component: linear algebra | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Changes (by rbeezer):
* priority: major => minor
* type: defect => enhancement
Old description:
> I discovered this while working on #12541. Documentation says the
> `check` will "coerce entries of gens into base field." This does not
> appear to be happening, and should.
>
> First example is the root problem - second just shows that the `check`
> flag seems ineffectual. I haven't looked at the code yet.
>
> {{{
> sage: (QQ^2).span(gens=[vector(QQ, [1,1/2])], base_ring=ZZ, check=True)
> Free module of degree 2 and rank 1 over Integer Ring
> Echelon basis matrix:
> [ 1 1/2]
> sage: (QQ^2).span(gens=[vector(QQ, [1,1/2])], base_ring=ZZ, check=False)
> Free module of degree 2 and rank 1 over Integer Ring
> Echelon basis matrix:
> [ 1 1/2]
> }}}
New description:
I discovered this while working on #12541. Documentation says the `check`
will "coerce entries of gens into base field." This does not appear to be
happening, and should. (Edit: this is an integral span of rational
vectors, a construction that is intended, so improving the documentation
might be in order.)
{{{
sage: (QQ^2).span(gens=[vector(QQ, [1,1/2])], base_ring=ZZ, check=True)
Free module of degree 2 and rank 1 over Integer Ring
Echelon basis matrix:
[ 1 1/2]
}}}
--
Comment:
See some discussion on #12541.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12688#comment:2>
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