[Pkg-scicomp-devel] Bug#490288: Bug#490288: glpk: Fails on assertion
Andrew Makhorin
mao at gnu.org
Sat Jul 12 14:06:56 UTC 2008
Saturday, July 12, 2008, 5:56:31 PM, you wrote:
> * Andrew Makhorin <mao at gnu.org> [2008-07-12 16:06]:
>> The failure appears due to insufficient robustness of the glpk mip
>> solver. It is mainly caused by unbounded integer variables (x1 and x2
>> have no upper bound) having relatively large coefficients in the
>> constraint that leads to excessive round-off errors on solving LP
>> relaxation.
>>
>> [sinp]
>>
>> Nevertheless, in both cases the problem is badly formulated. Many
>> reseachers do not recommend to use upper bounds of integer variables
>> which exceed 100.
> Does this mean that the problem is in the formulation of that specific
> example or is it a bug in GLPK? If the later is the case, are you
> planning to fix it?
It is a bug in the sense that the mip solver should return GLP_EFAIL
rather than cause abnormal termination. The bug will be fixed in a next
version of the package.
Andrew Makhorin
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