Originally posted by: alfablac

I need to code a product of two sum in my problem.

The minimization function is

I'm doing like this:

IloExpr obj(env);

}

thanks in advace. Any help is appreciated

Originally posted by: Ibrahim_Capar

You need to reset obj_part after each iteration.  So I think the code should be:

IloExpr obj(env);

for(int T = 0 ; T < 2; T++) {
    for(int i = 0 ; i < n; i++) {
        for(int j = 0 ; j < n; j++) {
            IloExpr obj_part(env);
            for(int K = 0 ; K < k; K++) {
                obj_part += x[T][k][i][j];
            }
            obj += c[T][i][j]*obj_part;
            obj_part.end();
        }
    }
}

Ibrahim is correct about needing to reset obj_part. While that is definitely a bug, it may not be causing CPLEX to fail. You need to clarify what you mean by "stop working". Is CPLEX throwing an exception?