#19872: regular symmetric Hadamard matrices for n=324
-------------------------+-------------------------------------------------
Reporter: | Owner:
dimpase | Status: positive_review
Type: | Milestone: sage-7.0
enhancement | Resolution:
Priority: major | Merged in:
Component: graph | Reviewers: Nathann Cohen
theory | Work issues:
Keywords: | Commit:
Authors: Dima | 567608be0b53ec173be1f1a755af202c4a4de564
Pasechnik | Stopgaps:
Report Upstream: N/A |
Branch: |
public/JKandJKT |
Dependencies: |
#19861 |
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Comment (by dimpase):
Replying to [comment:15 ncohen]:
> Dima: in Python a call to 'map' creates a new list in memory. Do you
understand of painful that makes it to read changes like that?
> {{{
> - for j in b:
> + for j in map(lambda x: x[0], st.OrbitsDomain(b)):
> }}}
> A new list in memory only because you want j[0] instead of j?...
no, it's actually two changes; say, if `st` was a Sage `PermutationGroup`
it would be
{{{
- for j in b:
+ for j in map(lambda x: x[0], st.orbits(b)):
}}}
to discard taking representatives of the same orbit of `st` (a 3 to 4-fold
speedup), and then the translation to libGAP (another 3-fold speedup) is
{{{
- for j in map(lambda x: x[0], st.orbits(b)):
+ for j in map(lambda x: x[0], st.OrbitsDomain(b)):
}}}
OK, I should have used `imap`.
--
Ticket URL: <http://trac.sagemath.org/ticket/19872#comment:17>
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