Originally posted by: srinit34

Hi 

I have an Ilocplex object into which I add some variables, an objective, and some constraints.

Then I solve the Ilocplex object.

Now I want to remove some variables, and add some new variables. Some of the constraints and objective will change because of this.

Now I want to solve the Ilocplex object again.

The key point here is that , I do not want to reconstruct the entire Ilocplex object again from scratch.

Can this be done? It seems we can remove some old constraints and variables, and add new ones. But I am not sure if the IloCplex object can be modified, solutions reset, and solved from scratch again ?

Yes, all the modifications you described can be done and the expected things will happen.

If you want to start the new solve from scratch then set parameter IloCplex::AdvInd to 0. If you don't set then CPLEX will use the feasible solutions from the previous solve as MIP starts for the next solve.

Originally posted by: srinit34

If I have changed the variables, then  does CPLEX take the old feasible solution grow it into a feasible MIP start for the model with new variables?

Basically what I am asking is, how do you reuse the old feasible solution? After all, I have changed some variables.

What I am doing in my program  is that I joining 2 chocolate bars together and solving the model.

Then I want  to break the joint chocolate bar into individual bars, and solve the model again.

So I would like to retain the MIP start but not sure if it can be done without extracting the solution and explicitly specifying a MIP start for the edited model.