Turning off Presolve option in CPLEX OPL

Question

Does anyone know how to disable "presolve" in CPLEX? (without using Java, C++, etc.)

My CPLEX Version is 12.4, in case it makes a difference.

Thanks in advance,

Answer 1

After trying to find how certain parameters can be changed in CPLEX, I have found the answer to my own question.

To change parameters (using CPLEX only) you don't need to type in any code. All you have to do is creating a "Settings" file within your project file.

You can follow these steps:

1. In the "OPL Projects" window right click and select "New->Settings"
2. Give a name to your settings file and click OK.
3. Change the parameters as you wish (to find the related setting you can type in the name of the parameter in the search bar, in my case it worked when i searched for "Preprocessing". From the menu that appeared I unchecked the box called "Presolve indicator")
4. Add the "Settings" file to your desired Run Configuration file to apply changes. In this case, CPLEX uses the parameters in your Settings file instead of the default values.

And that is all :)

Answer 2

Type those commands in order:

set
preprocessing
presolve
n

these will disable the preprocess indicator parameter. Does the same as Dubeddo's and Joris's answers.

Answer 3

Although the question was asked for OPL, it is also useful to know how to do this in Java/CPP/interactive optimizer.

Solution: set parameter preind to false

• Java: IloCplex.Param.Preprocessing.Presolve E.g. java: cplex.setParam(IloCplex.BooleanParam.PreInd, false);
• CPP: IloCplex::Param::Preprocessing::Presolve
• C: CPXPARAM_Preprocessing_Presolve
• .net: Cplex.Param.Preprocessing.Presolve
• Iteractive optimizer: preprocessing presolve

See: http://www-01.ibm.com/support/knowledgecenter/SSSA5P_12.6.2/ilog.odms.cplex.help/CPLEX/Parameters/topics/PreInd.html