#16926: Merge the features of SymmetricGroupAlgebra and SymmetricGroup.algebra
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Reporter: nthiery | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/combinat/fix_sga-16926 | 947bed483cd03fbd03cc0741235e50fd8b568193
Dependencies: #17981 | Stopgaps:
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Comment (by tscrim):
I've made some tweaks to the permutations multiplication, which
significantly drops the number of function calls according to `%prun`, as
well as cythonizing it. Here's my timings:
{{{
sage: P = Permutations(5)
sage: x = P.random_element()
sage: y = P.random_element()
sage: %timeit x*y
10000 loops, best of 3: 61.2 µs per loop
sage: P = Permutations(100)
sage: x = P.random_element()
sage: y = P.random_element()
sage: %timeit x*y
1000 loops, best of 3: 167 µs per loop
}}}
Before:
{{{
sage: %timeit x*y
10000 loops, best of 3: 87.3 µs per loop
sage: %timeit x*y
1000 loops, best of 3: 210 µs per loop
}}}
I don't care so much on `retract_okounkov_vershik`, but since you say its
a very minor regression, I'm not going to consider it (in fact, it might
be faster now with faster multiplication). Here's some timings of
`left_action_product`:
{{{
sage: P = Permutations(5)
sage: x = P.random_element()
sage: Q = Permutations(100)
sage: y = Q.random_element()
sage: %timeit x*y
1000 loops, best of 3: 300 µs per loop
sage: %timeit x.left_action_product(y)
10000 loops, best of 3: 167 µs per loop
}}}
Before:
{{{
sage: %timeit x*y
1000 loops, best of 3: 225 µs per loop
sage: %timeit x.left_action_product(y)
1000 loops, best of 3: 212 µs per loop
}}}
So there's ~20% slowdown when multiplying different parents, which
surprises me somewhat. Let me see if I can fix that for a few minutes...
--
Ticket URL: <http://trac.sagemath.org/ticket/16926#comment:45>
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