#18137: Centrality betweenness in Sage
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Reporter: | Owner:
ncohen | Status: needs_review
Type: | Milestone: sage-6.6
enhancement | Resolution:
Priority: major | Merged in:
Component: graph | Reviewers:
theory | Work issues:
Keywords: | Commit:
Authors: | 2f2fbd47b8527ca6a4dac02f01f8c2167907cd20
Nathann Cohen | Stopgaps:
Report Upstream: N/A |
Branch: |
u/ncohen/18137 |
Dependencies: |
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Comment (by vdelecroix):
At least from the following example, the computation with double is
perfectly valid
{{{
sage: g = graphs.RandomGNP(100,.2)
sage: cb0 = g.centrality_betweenness(exact=0)
sage: cb1 = g.centrality_betweenness(exact=1)
sage: max(cb0[i]-cb1[i] for i in cb0)
6.938893903907228e-18
}}}
The mantissa of the double is `2^(-53) ~ 10^(-16)` and the numbers are
about `0.01` which makes the error affect only the one or two last bits.
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Ticket URL: <http://trac.sagemath.org/ticket/18137#comment:19>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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