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Re[2]: [Help-glpk] Solving a large LP problem

From: Andrew Makhorin
Subject: Re[2]: [Help-glpk] Solving a large LP problem
Date: Thu, 15 Jul 2004 21:13:42 +0400

>I had one question though. My output seems to be showing that the
>presolve stage is already over and its trying to solve the presolved 
>problem. In that case, will --nopresol be of any use?

>>lpx_simplex: original LP has 243742 rows, 364514 columns, 1148311 non-zeros
>>lpx_simplex: presolved LP has 90344 rows, 203072 columns, 487180 non-zeros
>>lpx_adv_basis: size of triangular part = 89732
>>umalloc: size = 3614184; malloc failed

Yes, the output indicates that the presolver successfully transformed
the problem, and lpx_simplex started solving it. However, the presolver
keeps a lot of data needed to recover solution of the original problem.
These data are kept in the memory until the transformed problem has been
solved, and specifying `--nopresol' allows freeing out that memory.

Andrew Makhorin

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