Re: [Help-glpk] Problem size limit?

[Andrew Makhorin]

> Having looked at a problem with two columns that glpk finds
> difficult here is one with over a million that it solves 
> suprisingly well.

Mainly due to the simple matrix structure and the fact that your
instance needs no simplex iterations, since the optimal basis is
obvious (to the initial basis routine). Starting from the standard
basis (--std) might demonstrate that the instance is really hard for
the simplex solver.

> To set e to 21 should be possible with 4GB memory. Interesting to 
> see if a 64-bit OS is required. 22 or more will probably need a 
> professional computer.

The mathprog translator is greedy to the memory. I think using mps
or lp plain format and disabling the lp presolver might essentially
decrease the memory loadness.

> Benchmark.mod may be included in glpk's examples if you think that 
> challenging glpk is interesting.

Thank you for your example. (Unfortunately I cannot run it, because
my machine has only 256Mb of RAM.)


Andrew Makhorin