Storing the size of the reduced MIP and the LP-relaxation in parameters

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bjoern
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Storing the size of the reduced MIP and the LP-relaxation in parameters

Post by bjoern » 2 weeks ago

Hi all,

I'm using CPLEX to solve multiple MIP problems. In the log-file I noticed, that CPLEX reduces the size of the problem during Presolve. It says something like:

[...]
MIP Presolve eliminated 21 rows and 39 columns.
Aggregator did 30 substitutions.
Reduced MIP has 240 rows, 467 columns, and 1219 nonzeros.
Reduced MIP has 5 binaries, 0 generals, 0 SOSs, and 0 indicators.
[...]

Is there a way to store the number of rows, columns, nonzeros and binaries in parameters? Ideally, I'm looking for something similar to "modelname.numVar", but for the reduced problems!

An additional question: As far as I know, CPLEX internally performs a LP-Relaxation before solving the MIP problem. Is there a way to show the objective value of this relaxation in the log file? And, similarly to above, is there a way to store this objective value in a scalar/parameter? I guess that I could solve an additional model using "RMIP" for the relaxation, but ideally, I'm looking for a quicker way.

Thank you in advance for your help!

Regards,
bjoern

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