solver specific parameters settings supported in ortools

[Haoxian Zhao]

hi there,

I am using or-tools to build a MIP model (it is fantastic, thanks for making it available!) and it is being solved by SCIP, I would like to tweak some of the variable of the solver (as described in here) but not sure how this can be done with or-tools? if this is not supported, could you please share some advice on how I can achieve this? thanks 

regards

Haoxian

[Frederic Didier]

On Wed, Aug 5, 2015 at 7:36 AM, Haoxian Zhao <hao...@zhao.uk> wrote:

hi there,

I am using or-tools to build a MIP model (it is fantastic, thanks for making it available!) and it is being solved by SCIP, I would like to tweak some of the variable of the solver (as described in here) but not sure how this can be done with or-tools? if this is not supported, could you please share some advice on how I can achieve this? thanks 

with SCIP, you should be able to use SetSolverSpecificParametersAsString("..."); using the SCIP parameter format in the provided string.

 

regards

Haoxian

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[Pooya Rezaei]

Does this work? We are trying to limit the optimization solution time, say to 60 seconds, by passing "limits/time  = 60" to SetSolverSpecificParametersAsString() in C#, but it does not work, i.e., the optimization continues to run. I know there is another way to limit the optimization time using SetTimeLimit(), but I am trying to do this to test for other parameters, specifically SCIP optimization tuning parameters.

[AM]

Yes I tried it on CPLEX to set the lower objective and It didn't work either.

https://www.ibm.com/support/knowledgecenter/SSSA5P_12.8.0/ilog.odms.cplex.help/CPLEX/Parameters/topics/ObjLLim.html

Using CPLEX interactive command:

SetSolverSpecificParametersAsString("simplex limit lowerobj -3000");

and I am getting this warning:

W0403 15:03:23.649812  6204 linear_solver.cc:1428] Error in SetSolverSpecificParametersAsString() for solver type: CPLEX_LINEAR_PROGRAMMING

what am I missing? Is syntax within the string wrong?