使用cplex和java创建两种因变量

Question

I am new to work by CPLEX. My simplified optimization problem is:

 objective function: 
            Maximize z1 + z2 + z3
 Subject to:   
            c1: x1 - 3 x2 + x3 <= 30
            c2: x1 + x2 + x3 >= z1
            ...
 Bounds
            x1=[0,1]
            x2=[0,1] 
            ...

To model this problem, my code is:

public static void main(String[] args) {
    try {

        IloCplex cplex = new IloCplex();            
        IloNumVar[] z = cplex.numVarArray(3, 0.0, 1.0);
        IloLinearNumExpr objectiveExpr = cplex.linearNumExpr();

        IloLinearNumExpr constraintExpr1 = cplex.linearNumExpr();
        IloLinearNumExpr constraintExpr3 = cplex.linearNumExpr();
        IloNumVar[] x = cplex.numVarArray(3, 0.0, 1.0);
        for (int i = 1; i < 3; i++){
            objectiveExpr.addTerm(1, z[i]);
        }
        IloObjective obj = cplex.maximize(objectiveExpr);
        cplex.add(obj); 
        constraintExpr1.addTerm(1, x[1]);
        constraintExpr1.addTerm(-3, x[2]);
        constraintExpr1.addTerm(1, x[3]);
        cplex.addLe(constraintExpr1, 30);

        constraintExpr2.addTerm(-1, x[1]);
        constraintExpr2.addTerm(1, x[2]);
        constraintExpr2.addTerm(1, x[3]);
        cplex.addGe(constraintExpr2, z[1]);
        .
        .
        .
    }
    catch (IloException e){
        System.err.println("Concert exception '" + e + "' caught");
    }


}

The generated model of this code is:

objective function:  
           Maximize x1 + 2 x2 + 3 x3
Subject To:               
           c1: x7 - 3 x8 + x9 <= 30
           c2: - x1 - x7 + x8 + x9 <= 0
Bounds
           0 <= x1 <= 1
           ...

If it starts to model the constraints from x4 instead of x7, I could distinguish x and z easily.

Answer 1

Unlike David, I do know CPLEX for about 17 years, but I also don't understand what your problem is. Can you explain in what way the generated model is different from what you expected - we can probably work this out ourselves, but it seems daft for potentially many of us to have to spend extra time understanding your problem when you could explain better.

Can I suggest that you name your variables and constraints using setName(...) so that you can see better what is happening in the generated model.