[Help-glpk] memory usage seems very high

[Nicholas Farrell]

Hi all.

We have been looking at using glpsol for optimising a set of variables against a moderately large number of target constraints. It all works well, except for the amount of memory being used. Can anyone offer an insight on what part is using the additional memory?

For example, when I run the mod file at http://pickup.nieir.com.au/big.mod.gz I get the following, showing ~2Gb was needed. We would actually like to solve significantly larger problems than this, but the amount of memory being used may prevent us.

Thanks in advance for any advice/insights.

Nick Farrell.

> Model has been successfully generated
> glp_simplex: original LP has 93 rows, 5256 columns, 84143 non-zeros
> glp_simplex: presolved LP has 82 rows, 5256 columns, 77163 non-zeros
> Scaling...
>  A: min|aij| =  1.000e+00  max|aij| =  1.600e+02  ratio =  1.600e+02
> GM: min|aij| =  4.952e-01  max|aij| =  2.019e+00  ratio =  4.077e+00
> EQ: min|aij| =  2.471e-01  max|aij| =  1.000e+00  ratio =  4.048e+00
> Crashing...
> Size of triangular part = 82
>       0: obj =   0.000000000e+00  infeas =  5.657e+00 (0)
> *    50: obj =   1.410800000e+00  infeas =  0.000e+00 (0)
> *    80: obj =  -7.209526707e-32  infeas =  2.776e-17 (0)
> OPTIMAL SOLUTION FOUND
> Time used:   0.1 secs
> Memory used: 2008.7 Mb (2106232859 bytes)