Parameters

ILOG CPLEX 11.0 User's Manual > Languages and APIs > ILOG Concert Technology for Java Users > Controlling ILOG CPLEX Optimizers > Parameters

Parameters

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Parameters are manipulated by means of IloCplex.setParam. For example:

  cplex.setParam(IloCplex.BooleanParam.PreInd, false);

sets the Boolean parameter PreInd to false, instructing ILOG CPLEX not to apply presolve before solving the problem.

Integer parameters often indicate a choice from a numbered list of possibilities, rather than a quantity. For example, the class IloCplex.PrimalPricing defines constants with the integer parameters shown in Table 2.5, Constants in IloCplex.PrimalPricing for better maintainability of the code.

Table 2.5 Constants in IloCplex.PrimalPricing

Integer Parameter	Constant in class `IloCplex.PrimalPricing`
`0`	`IloCplex.PrimalPricing.Auto`
`1`	`IloCplex.PrimalPricing.Devex`
`2`	`IloCplex.PrimalPricing.Steep`
`3`	`IloCplex.PrimalPricing.SteepQStart`
`4`	`IloCplex.PrimalPricing.Full`

Thus, the suggested method for setting steepest-edge pricing for use with the primal simplex algorithm looks like this:

cplex.setParam(IloCplex.IntParam.PPriInd,
                IloCplex.PrimalPricing.Steep);

Table 2.6 gives an overview of the classes defining constants for parameters.

Table 2.6 Classes with Parameters Defined by Integers.

class	for use with parameters:
`IloCplex.Algorithm`	`IloCplex.IntParam.RootAlg IloCplex.IntParam.NodeAlg`
`IloCplex.MIPEmphasis`	`IloCplex.IntParam.MIPEmphasis`
`IloCplex.VariableSelect`	`IloCplex.IntParam.VarSel`
`IloCplex.NodeSelect`	`IloCplex.IntParam.NodeSel`
`IloCplex.DualPricing`	`IloCplex.IntParam.DPriInd`
`IloCplex.PrimalPricing`	`IloCplex.IntParam.PPriInd`

Parameters can be queried with method IloCplex.getParam and reset to their default settings with method IloCplex.setDefaults. The minimum and maximum value to which an integer or double parameter can be set is queried with methods IloCplex.getMin and IloCplex.getMax, respectively. The default value of a parameter is obtained with IloCplex.getDefault.

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