#18635: Move WeylGroups.ElementMethods.reflection_to_root to
WeylGroups.ParentMethods.reflection_to_positive_root
-----------------------------------------------+------------------------
Reporter: stumpc5 | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.8
Component: categories | Resolution:
Keywords: wely groups, coxeter groups | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
-----------------------------------------------+------------------------
Comment (by mshimo):
I don't really see a clear win nor rationale in making this a parent
method.
You still have to specify the Weyl group element
and now in addition the parent must be accessed.
In the parent method there is still the danger that the
element is not a reflection and the method call "doesn't make sense".
In the Weyl groups case, from my viewpoint it is useful to give the
result in the combination-of-simple-roots form, so I would prefer to keep
this.
If you are worried about having a uniform kind of output
after generalizing to complex reflection groups,
you can always coerce the answer from the
root lattice to the ambient space and then coerce further to
just a vector.
One big reason for keeping the integer-combination-of-simple-roots
form is that it is by definition integral.
The ambient spaces are only rational and therefore cannot be
straightforwardly coerced back to the integer lattices.
Final comment: someone should think about using general retractions to
recognize when
a rational vector is integral or when an element of the weight lattice is
in the root lattice,
etc.
--
Ticket URL: <http://trac.sagemath.org/ticket/18635#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
