Originally posted by: A.Omidi

Hello everybody,

Can you please show what you got so far and what the errors are you get?

Also, I am not exactly clear what

set: {(i,k) in 1,2,3,4,5,6};

is supposed to mean. (i,k) is a pair so it cannot be an element of a set that has only numbers. Do you mean "(i,k) such that i and k are in 1..6"?

Moreover, in

constraint (m,k):    comp(m,k) = start(m,k) + sum((i), time(m,i)*rank(i,k));

what is i?

Originally posted by: A.Omidi

Dear Mr. Junglas,

According to your comment on the problem, I have two sets.
The first, number of works, {1,2,3,4,5,6}, and the second, number of resources, {A,B,C}.

I define two indexes [i],[k] in the works and index [m] in the resources.

The model has a constraint in the below form:
*=======================
forall(k in works, m in resources)
    comp(m,k) == start(m,k) + sum((i in works), time(m,i)*rank(i,k));
where comp, start and rank are variables and time is given parameter.
*=======================

I was trying to write the model in the Java language using IDE.
The form of code is such as below:
*=======================
for (int k = 0; k < works; k++) {
    for(int m=0; m < resource; m++){
        IloLinearNumExpr constraint = model.linearNumExpr();
        for (int i = 0; i < works; i++) {
            constraint.addTerm(1, comp[j]);
            constraint.addTerm(-1, start[j]);
            constraint.addTerm(-time[m][i], rank[i][k]);
        }
                model.addEq(constraint, 0);
    }
}
*=======================

When I solve the model, it does not have the correct solution.
Please, let me know, how can I write this constraint?

Best regards

Originally posted by: Lessi

I think you should export the model to see if you write it correctly.   

Even before you export the model (which is a good idea for debugging), some things don't add up at all: In your textual description, variables comp and start are indexed by m and k. In your code however both are only indexed by j. That looks weird.

Moreover, you are not only summing up the time*rank terms. You are also summing up comp and start! I guess you should at least move these two statements

constraint.addTerm(1, comp[j]);
constraint.addTerm(-1, start[j]);

out of the inner loop.