#7754 closed enhancement (fixed)
Weyl group optimizations
Reported by: | Nicolas M. Thiéry | Owned by: | Nicolas M. Thiéry |
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Priority: | major | Milestone: | sage-4.3.1 |
Component: | combinatorics | Keywords: | Weyl groups |
Cc: | Daniel Bump | Merged in: | sage-4.3.1.alpha0 |
Authors: | Nicolas M. Thiéry | Reviewers: | Daniel Bump |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
- faster hash method calling the hash of the underlying matrix (which is set as immutable for that purpose)
- new eq method
- action on the weight lattice realization: optimization of the matrix multiplication
Depends (trivially) on #7753
This indirectly improve most Weyl group routines:
Without the patch:
sage: W = WeylGroup(["F",4]) sage: W.cardinality() 1152 sage: time l=list(W) CPU times: user 12.14 s, sys: 0.06 s, total: 12.20 s Wall time: 12.20 s sage: W = WeylGroup(["E",8]) sage: time w0 = W.long_element() CPU times: user 1.71 s, sys: 0.01 s, total: 1.72 s Wall time: 1.72 s
With the patch:
sage: W = WeylGroup(["F",4]) sage: W.cardinality() 1152 sage: time l=list(W) CPU times: user 7.96 s, sys: 0.04 s, total: 8.00 s Wall time: 8.01 s sage: W = WeylGroup(["E",8]) sage: time w0 = W.long_element() CPU times: user 1.40 s, sys: 0.00 s, total: 1.41 s Wall time: 1.42 s
Honestly, this is still ridiculously slow; luckily there still is much room left for improvements by improved caching and optimizations of the underlying tools (CombinatorialFreeModules?, ...).
Attachments (1)
Change History (10)
Changed 13 years ago by
Attachment: | trac_7754_weyl_group_optimizations-nt.patch added |
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comment:1 Changed 13 years ago by
Description: | modified (diff) |
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Status: | new → needs_review |
comment:2 follow-up: 6 Changed 13 years ago by
Status: | needs_review → positive_review |
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Summary: | Weyl group optimizations → Weyl group optimizations [with patch, positive review] |
comment:4 Changed 13 years ago by
Merged in: | → sage-4.3.1.alpha0 |
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Resolution: | → fixed |
Status: | positive_review → closed |
comment:5 Changed 13 years ago by
Summary: | Weyl group optimizations [with patch, positive review] → Weyl group optimizations |
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comment:6 follow-up: 8 Changed 13 years ago by
Replying to bump:
It is a very substantial speed-up. It cuts a few seconds off
sage -t weyl_groups.py
but more importantly it about doubles the speed of computing the reduced word of a Weyl group element, which is the basis of most combinatorial algorithms.
Hi Dan and Nicolas,
I'm doing a release tour of the features of this ticket, see the Sage wiki page. Is there some sample code I could use to show the speed-up implemented by this ticket?
comment:7 Changed 13 years ago by
Description: | modified (diff) |
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comment:8 Changed 13 years ago by
Hi Dan and Nicolas,
I'm doing a release tour of the features of this ticket, see the Sage wiki page. Is there some sample code I could use to show the speed-up implemented by this ticket?
Yup, see the updated description!
comment:9 Changed 13 years ago by
Description: | modified (diff) |
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I tested this patch without #7753. I tested it with and without the patch in #7751.
It is a very substantial speedup. It cuts a few seconds off
sage -t weyl_groups.py
but more importantly it about doubles the speed of computing the reduced word of a Weyl group element, which is the basis of most combinatorial algorithms.There are three patch fragments, one replacing the hash method with the hash of the underlying matrix, one replacing the
__eq__
method, and one unraveling some unnecessary complexity in the Weyl group action. I tested each patch fragment separately and found that they are all speedups, the last one being very significant.