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Re: [Help-glpk] glpksol default settings

From: Andrew Makhorin
Subject: Re: [Help-glpk] glpksol default settings
Date: Tue, 29 Jul 2008 17:05:53 +0400

> Thanks, I changed it and I can kind of reproduce glpsol's behaviour,
> but now I pinpointed the problem to this LP:
> glpsol --cpxlp lpQ_bad.txt
> give UNBOUNDED solution here. However, both
> glpsol --std --cpxlp lpQ_bad.txt
> and
> glpsol --adv --cpxlp lpQ_bad.txt
> which is kind of weird.

Probably this happens because your instance is not well conditioned,
so due to excessive round-off errors the presolved lp is unbounded
while the original lp is not.

>  Also neither lpx_adv_basis nor lpx_std_basis
> seem to solve the problem from C++ API level. Could anyone please tell
> me what I am missing here?

Could you provide the code returned by glp_simplex?

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