[Couenne] Search direction

[Pietro Belotti]

Dear Sismail,

I believe those messages are printed by Ipopt, which is the nonlinear  
solver used to find a feasible solution for the MINLP problem. In  
principle, even if Ipopt exits with those messages Couenne should be  
able to continue and find an optimal solution. Can you be more precise  
on the meaning of "very bad solutions"? Are the optimal (as claimed by  
Couenne) solutions much worse than solutions you have found in some  
other way?

> Is something I can modify in the file mybonmin.opt to avoid such problem ?

I believe you should use an option file called couenne.opt, but anyhow  
I don't think there is any Couenne setting you should change. I  
suggest you search the Ipopt mailing list for help on how to get rid  
of those messages.

Hope this helps.

Cheers,
Pietro

_________________________________________
Pietro Belotti, Lehigh University
Dept. of Industrial & Systems Engineering
200 W Packer Ave, Bethlehem PA 18015.
phone: 610-758-3865   fax: 610-758-4886
email: belotti at lehigh.edu
web:   http://www.lehigh.edu/~pib208


On 12/21/2009, ksismail <ksismail1 at gmail.com> wrote:

> Dear Pietro,
>
> I got regularly a very bad solution when executing Couenne whith such
> periodical messages:
>
> in iteration .., slack too small, adjusting variable bound
>
> and depending of the size problem,
>
> EXIT: Search direction is becoming too small  or EXIT: Solved to Acceptable
> Level.
>
> Is something I can modify in the file mybonmin.opt to avoid such problem ?
>
> Regards,
>
> sismail
>



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