#13461: Another WeylCharacterRing speedup
---------------------------------+------------------------------------------
Reporter: bump | Owner: bump
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.4
Component: combinatorics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Daniel Bump | Merged in:
Dependencies: | Stopgaps:
---------------------------------+------------------------------------------
Description changed by bump:
Old description:
> After trac_13461-demazure-speedup.patch, if a WeylCharacterRing is
> created with style="coroots",
> characters are computed using not the Freudenthal multiplicity formula,
> but
> rather the Demazure character formula. This can be done using only
> integer
> addition and subtraction. If we run {{{sage -t --long
> weyl_characters.py}}},
> it is more than twice as fast (26 seconds versus 69 seconds) as
> previously.
> If we omit {{{--long}}} it is slightly slower, so there is a speedup for
> big computations and a slight penalty for small ones.
>
> Demazure characters are added as a method of WeylCharacterRing and the
> Demazure operators are implemented as methods of WeightRing elements.
>
> The second patch trac_13461-demazure-lusztig.patch implements Demazure-
> Lusztig
> operators as a method of the weight ring. For documentation see:
>
> http://sporadic.stanford.edu/bump/reference-5.4.beta1/sage/combinat/root_system/weyl_characters.html
New description:
After trac_13461-demazure-speedup.patch, if a WeylCharacterRing is created
with style="coroots",
characters are computed using not the Freudenthal multiplicity formula,
but
rather the Demazure character formula. This can be done using only integer
addition and subtraction. If we run {{{sage -t --long
weyl_characters.py}}},
it is more than twice as fast (26 seconds versus 69 seconds) as
previously.
If we omit {{{--long}}} it is slightly slower, so there is a speedup for
big computations and a slight penalty for small ones.
Demazure characters are added as a method of WeylCharacterRing and the
Demazure operators are implemented as methods of WeightRing elements.
The second patch trac_13461-demazure-lusztig.patch implements Demazure-
Lusztig
operators as a method of the weight ring. For documentation see:
http://sporadic.stanford.edu/bump/reference-5.4.beta1/sage/combinat/root_system/weyl_characters.html
Apply:
{{{
trac_13461-demazure-speedup.patch
trac_13461-demazure-lusztig.patch
}}}
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13461#comment:4>
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 post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
