[Coin-ipopt] Lagrange Multipliers in AMPL

[Andreas Waechter]

Dear Karsten,

I just changed the AMPL interface, so that the Lagrangian multipliers are
now passed back to AMPL.  You can get the corrected source file

COIN/Ipopt/IPOPT/AMPL_interface/ipoptAMPL.c

via CVS, or download it directly from the web:

http://www-124.ibm.com/developerworks/opensource/cvs/coin/COIN/Ipopt/IPOPT/AMPL_interface/ipoptAMPL.c?rev=1.4

or wait until is it included in tomorrows tarball.

With this, the multiplier information should be accessible to you in the
way outlined in your message.

I hope this helps,

Andreas

On Wed, 28 Apr 2004, Arvind Uppili Raghunathan wrote:

> Dear Karsten,
>
>   In the current AMPL interface for IPOPT we chose not to return the
> multipliers but that can be fixed easily. Andreas can easily fix that in
> the next release.
>
> Cheers
> Arvind
>
> On Wed, 28 Apr 2004, Karsten Theissen wrote:
>
> > Hello IPOPT-Experts,
> >
> > after some problems in the beginning, everything is working now! Everything??
> > Of course not ;-), but i think it is only a small problem.
> >
> > I test all my old and new AMPL-LOQO problems with IPOPT (and by the way IPOPT
> > is doing a great job...) but there are some problems with the Lagrange
> > multipliers. When I was working with LOQO you can get them by evaluating the
> > name of your constraints e.g. with
> >
> > s.t. dgl1{i in 0..Nt-1}:
> >
> > you get them with
> >
> > dgl1[i]     i=1..Nt-1
> >
> > I think with IPOPT it should be the same but there are all equal to zero.
> > Maybe it is only a question of a missing ipopt_option.
> > It would be nice if anybody could help.
> >
> > Greetings
> >
> > Karsten Theißen
> >
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> >
> >
>
>
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