[Ipopt] Cutting back alpha due to evaluation error

[Martin Schmidt]

Hi Stefan,

although it seems to be a little bit off topic: Is there a possibility 
in GAMS to detect the place of interest in the model?

Best regards,
Martin

Am 08.06.2011 12:04, schrieb Stefan Vigerske:
> Hi,
>
> that the point cannot be evaluated is already recognized in the function
> evaluation code (probably to GAMS AD library in your case), the Ipopt
> interface then just signals to Ipopt that the given point could not be
> evaluated.
> Unfortunately, I do not see a place in the code that would print the
> point before or after calling the evaluation routines.
> If you can modify Ipopt code, then try to activate the
> DBG_PRINT_VECTOR's in
> IpoptCalculatedQuantities::trial_primal_infeasibility().
>
> Stefan
>
>
>> 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
>>
>> _______________________________________________
>> Ipopt mailing list
>> Ipopt at list.coin-or.org
>> http://list.coin-or.org/mailman/listinfo/ipopt
>>
>
>


-- 
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- Dipl.-Math. Martin Schmidt		  -
- Institut für Angewandte Mathematik	  -
- AG Algorithmische Optimierung		  -
- Leibniz Universität Hannover		  -
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