#14094: Iterating through Partitions(n) for n>=1000.
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Reporter: nthiery | Owner: sage-combinat
Type: defect | Status: new
Priority: major | Milestone: sage-5.7
Component: combinatorics | Keywords: days45
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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As discovered live during the Sage Days 45 tutorial, the default fast
iterator for Partitions(n) is recursive and breaks for n>988:
{{{
sage: P = Partitions(988)
sage: for p in P: print p
Traceback (most recent call last):
File "<ipython console>", line 1, in <module>
File "/opt/sage-5.6/local/lib/python2.7/site-
packages/sage/combinat/partition.py", line 4282, in __iter__
sage: all(test(mu,k) for k in range(1,5)
File "/opt/sage-5.6/local/lib/python2.7/site-
packages/sage/combinat/partition.py", line 4312, in _fast_iterator
new_w.sort(reverse=True)
File "/opt/sage-5.6/local/lib/python2.7/site-
packages/sage/combinat/partition.py", line 4312, in _fast_iterator
new_w.sort(reverse=True)
}}}
Whereas the generic iterator works:
{{{
sage: P = Partitions(988, max_part=1000)
sage: for p in P: print p
[988]
[987, 1]
[986, 2]
[986, 1, 1]
[985, 3]
}}}
Possible fix: either make the fast iterator non recursive, or default to
the generic iterator.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14094>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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