#12220: Updated CBC spkg
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Reporter: ncohen | Owner: ncohen
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-5.0
Component: linear programming | Keywords: sd35.5, Cernay2012
Work_issues: | Upstream: N/A
Reviewer: | Author: John Perry
Merged: | Dependencies:
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Comment(by john_perry):
Replying to [comment:55 ncohen]:
> Well, I expect that such noise isplatform dependent...
That wouldn't surprise me. In fact, I am working on a machine that I
didn't have the last time I tried this patch on Linux, which is probably
the reason it occurred.
> Could you check that it is indeed a rounding problem ?
What exactly should I check? I traced through the code, and found that one
of the `box`es contains the following result:
{{{
{0: {0: 1.0, 1: 0.0, 2: 0.0}, 1: {0: 0.0, 1: 0.0, 2: 1.0}, 2: {0: 0.0, 1:
0.0, 2: 1.0}, 3: {0: 0.0, 1: 0.99999999999999989, 2: 0.0}, 4: {0: 1.0, 1:
0.0, 2: 0.0}}
}}}
Once I saw the 0.999... I figured you knew what the issue was better than
I. `:-)`
> I thought the solver interfaces had all been asked to round the values
of integer-type variables, but if it is not the case this should be done
for GLPK (trivial stuff).
I was under the impression that Cbc was called as the default solver when
it's installed, so wouldn't that be the one to patch? or am I wrong?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12220#comment:56>
Sage <http://www.sagemath.org>
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