[Ipopt] Cutting back alpha due to evaluation error

[Andreas Waechter]

Hi,

It seems you are using GAMS.  If you however also have an AMPL model, you 
can set the option

halt_on_ampl_error yes

from within AMPL (ipopt_options... it will not work from ipopt.opt).  Then 
AMPL will stop in case of an evaluation error and tell you which 
constraint is causing the trouble.

Andreas

On Wed, 8 Jun 2011, Martin Schmidt wrote:

> Hi,
>
> I have an NLP for which I often get the message
>
> 	"Warning: Cutting back alpha due to evaluation error".
>
> I know that this has something to do with constraints that are not well
> defined at the current point (like sqrt of negative numbers etc.).
>
> Is there any chance to analyze at which constraint in the model the
> problems occurs? I thought I could find some "inf" or "nan" values in
> the higher output levels but I didn't find anything.
>
> Thanks in advance,
> Martin
>
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