#17920: Reimplement IntegerLists using Polyhedron.integral_points()
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Reporter: jdemeyer | Owner:
Type: enhancement | Status: needs_review
Priority: blocker | Milestone: sage-6.6
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jeroen Demeyer | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jdemeyer/ticket/17920 | 5f81a0a08bed2dc5c73f8f99dd32deafdfb3c9a1
Dependencies: #17937 | Stopgaps:
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Comment (by aschilling):
Replying to [comment:40 jdemeyer]:
> Replying to [comment:39 nthiery]:
> > Please do not change the enumeration order, at least as default
> I disagree with this: the default should be "do not sort, return stuff
in the fastest possible way". Sorting an iterator is very expensive and
should only be done if really needed.
>
> > quite some code depends on it
> Is that really true? The only doctest failures that I saw where
"obvious" failures where some list order changed, I didn't see anything
subtle.
What about
{{{
sage: spc = SymmetricGroupRepresentation([2,2,1], 'orthogonal')
sage: spc([1,3,2,4,5])
[ -1/2 1/2*sqrt(3) 0 0 0]
[1/2*sqrt(3) 1/2 0 0 0]
[ 0 0 -1/2 1/2*sqrt(3) 0]
[ 0 0 1/2*sqrt(3) 1/2 0]
[ 0 0 0 0 -1]
}}}
The output is a matrix which should really be indexed by conjugacy classes
of $S_n$, i.e. partitions. So the order here matters since currently it
means that the rows and columns are labelled by
{{{
sage: Partitions(5).list()
[[5], [4, 1], [3, 2], [3, 1, 1], [2, 2, 1], [2, 1, 1, 1], [1, 1, 1, 1, 1]]
}}}
If the order changes all the matrices need to be changed as well, I think.
--
Ticket URL: <http://trac.sagemath.org/ticket/17920#comment:52>
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