#11555: Expand print representation of free module morphisms
------------------------------+---------------------------------------------
Reporter: rbeezer | Owner: jason, was
Type: enhancement | Status: needs_review
Priority: minor | Milestone: sage-4.7.2
Component: linear algebra | Keywords: beginner
Work_issues: | Upstream: N/A
Reviewer: | Author: Rob Beezer
Merged: | Dependencies:
------------------------------+---------------------------------------------
Changes (by newvalueoldvalue):
* keywords: => beginner
* status: new => needs_review
* author: => Rob Beezer
Old description:
> Morphisms between free modules are basically represented by matrices.
> Here is how they sometimes print:
>
> {{{
> sage: V = ZZ^6
> sage: W = ZZ^4
> sage: m = matrix(QQ, [[1, 0, 0 ,0], [0]*4, [0]*4, [0]*4, [0]*4, [0]*4])
> sage: phi = V.hom(m, W)
> sage: rho = phi.restrict_codomain(W.span([W.0]))
> sage: rho
> Free module morphism defined by the matrix
> (not printing 6 x 1 matrix)
> Domain: Ambient free module of rank 6 over the principal ideal domain ...
> Codomain: Free module of degree 4 and rank 1 over Integer Ring
> Echelon ...
> }}}
>
> The cutoff (...) on the domains is totally arbitrary, at 60 characters.
>
> Here is the new output with upcoming patch:
>
> {{{
> Free module morphism defined by the matrix
> [1]
> [0]
> [0]
> [0]
> [0]
> [0]
> Domain: Ambient free module of rank 6 over the principal ideal domain
> Integer Ring
> Codomain: Free module of degree 4 and rank 1 over Integer Ring
> Echelon basis matrix:
> [1 0 0 0]
> }}}
New description:
Morphisms between free modules are basically represented by matrices.
Here is how they sometimes print:
{{{
sage: V = ZZ^6
sage: W = ZZ^4
sage: m = matrix(QQ, [[1, 0, 0 ,0], [0]*4, [0]*4, [0]*4, [0]*4, [0]*4])
sage: phi = V.hom(m, W)
sage: rho = phi.restrict_codomain(W.span([W.0]))
sage: rho
Free module morphism defined by the matrix
(not printing 6 x 1 matrix)
Domain: Ambient free module of rank 6 over the principal ideal domain ...
Codomain: Free module of degree 4 and rank 1 over Integer Ring
Echelon ...
}}}
The cutoff (...) on the domains is totally arbitrary, at 60 characters.
Here is the new output with upcoming patch:
{{{
Free module morphism defined by the matrix
[1]
[0]
[0]
[0]
[0]
[0]
Domain: Ambient free module of rank 6 over the principal ideal domain
Integer Ring
Codomain: Free module of degree 4 and rank 1 over Integer Ring
Echelon basis matrix:
[1 0 0 0]
}}}
'''Apply:'''
1. [attachment:trac_11555-free-module-morphism-printing.patch]
--
Comment:
Passes all long tests for 4.7.1.alpha3
Small chance this will bitrot, relative to some other patches I have up
for related files. I'll try to stay on top of it, but let me know if this
causes doctests failures.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11555#comment:1>
Sage <http://www.sagemath.org>
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