[Coin-ipopt] How to choose objective functions from multi-objective functions

[Rodrigo López Negrete de la Fuente]

Hi Rui,

In your ampl model, have you tried using the objective command, as described
in
http://groups.google.com/group/ampl/browse_thread/thread/1b6ab5cdfb462ee4

Because, as Andreas just mentioned, Ipopt can only handle one objective
function at a time. I've been using ampl's named problems with Ipopt without
any trouble, but I'm only specifying one objective function per problem.

hth,
  Rodrigo.

On 5/21/07, Andreas Waechter <andreasw at watson.ibm.com> wrote:
>
> Hi Rui,
>
> I think that we wrote the AMPL interface in Ipopt so that it complains (in
> the way you describe) when there are more than one objective functions in
> the model.   Maybe the trick that Michal mentioned already does the trick
> for you.
>
> If not, please submit a ticket at the Ipopt trac page and attach the AMPL
> model that give you trouble.
>
> Thanks,
>
> Andreas
>
> On Sun, 20 May 2007, Michal Kaut wrote:
>
> > Hello,
> >
> > you can use named problems, using the "problem" keyword. This is one of
> the
> > new features of AMPL, so you won't find it in the first edition of the
> book.
> > For a detailed description, including examples, see
> > http://ampl.com/NEW/loop2.html
> >
> > Regards,
> > Michal Kaut
> >
> >
> > Rui Huang wrote:
> >> Hello
> >>
> >> I have two objective functions.
> >> So I have two same ampl models, except that each one has a different
> >> objective function.
> >> and try to solve them together without "reset"
> >> But ampl breaks
> >> "There is more than one objective function in the AMPL model, but
> >> AmplTNLP::set_active_objective has not been called",
> >>
> >> I do not know how to call this function.
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-- 
Rodrigo López Negrete
http://muon.blogdns.org/~rush/ <http://muon.blogdns.org/%7Erush/>
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