#6621: [with patch, positive review] Permutation.inverse too slow
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Reporter: aclaesson | Owner: mhansen
Type: enhancement | Status: new
Priority: major | Milestone: sage-4.1.1
Component: combinatorics | Keywords:
Reviewer: Dan Drake | Author: Anders Claesson
Merged: |
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Changes (by ddrake):
* reviewer: => Dan Drake
Comment:
Positive review! Here are some timings:
For the permutation [6,7,8,9,4,2,3,1,5], on my machine, the timing went
from 70.9 µs per loop to 24.7 µs per loop. (This is all "%timeit
p.inverse()".
For [19, 5, 13, 8, 7, 15, 9, 10, 16, 3, 12, 6, 2, 20, 18, 11, 14, 4, 17,
1], it went from
263 µs per loop to 40 µs per loop.
For [14, 17, 1, 24, 16, 34, 19, 9, 20, 18, 36, 5, 22, 2, 27, 40, 37, 15,
3, 35, 10, 25, 21, 8, 13, 26, 12, 32, 23, 38, 11, 4, 6, 39, 31, 28, 29, 7,
30, 33], it went from 923 to 64.8. So it does look like this patch turns
quadratic behavior into linear behavior.
This is Anders' first contribution to Sage, by the way.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6621#comment:2>
Sage <http://sagemath.org/>
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