Originally posted by: regisgomes

Hi,

I implemented a constraint like this:

for (int i=0; i<d.m; i++){
    IloExpr r1(env);
    for (int j=1; j<=d.n; j++){
        r1 += mp.x[(d.n+1)*i + j]*d.p_ij[j][i+1];
    }
    r1 += mp.e[i] - mp.Cmax;
    mp.constraints.add(r1 <= 0);
    mp.constraints.setNames("r1");
    r1.end();
  }

Already found out that the method getAX is used to access the value of a row. But I can not do this.

Could you help me?

I want the value of a specific constraint.

Thank you.

> Already found out that the method getAX is used to access the value of a row. But I can not do this.
>
Please be more specific. What exactly is the problem?

> I want the value of a specific constraint.
>
What do you mean by "value of a constraint"? The value of its left-hand side? The slack? Its boolean value depending on whether it is satisfied or not?

Originally posted by: regisgomes

Hi Junglas,

I want the value of lhs of a constraint that I setting a name in best solution, but specifically when the best solution does not have all variables with integer value.

mp.constraints.setNames("r1");

I do not know properly pass the constraint which I want the value of the lhs best solution is not entire. I tried this way but it did not work:

cout << "r1 " << mp.cplex.getAX(mp.constraints[2]) << endl;

I used the number 2 just to test, I do not know how or if I can use the name "r1" constraint.

Thanks.

And what is the error you get for this?

Originally posted by: regisgomes

Thanks,

CPLEX Error 1006: Error during callback.

I am using ILOBRANCHCALLBACK.

Are you invoking IloCplex::getAX() in a callback? That is not supported. In that case use the callback's getValue() method on the expression returned by IloRange::getExpr(). This will also produce the value of the left-hand side of the constraint.

Originally posted by: regisgomes

Thanks,

Now it worked.

Just one more question, if I can setting a name in the constraint I can use this name in the getValue method to identify the constraint that I want to access? How do I do that?

No, you cannot use the name of a constraint as argument to getValue(). You can only pass references to constraints to that method.

Originally posted by: regisgomes

Thanks!

You helped me greatly.

It until a further.

Regis Gomes.