#6659: cores() is broken for some digraphs, and is *way* too slow
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Reporter: jason | Owner: rlm
Type: defect | Status: new
Priority: major | Milestone: sage-4.1.1
Component: graph theory | Keywords:
Reviewer: | Author: Jason Grout
Merged: |
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Comment(by jason):
An example of a speedup:
BEFORE:
{{{
sage: a=random_matrix(GF(2), 50000, density=0.0001,sparse=True)
sage: len(a.nonzero_positions())
125063
sage: c=DiGraph(50000)
sage: c.add_edges(a.nonzero_positions())
sage: %time
sage: e=c.cores(with_labels=True)
CPU time: 429.14 s, Wall time: 430.89 s
}}}
AFTER:
{{{
sage: d=c.cores(with_labels=True)
CPU time: 1.86 s, Wall time: 1.86 s
sage: e==d
True
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6659#comment:2>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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