[Couenne] Unknown operator error

[sguazt]

On Thu, Sep 8, 2011 at 6:12 PM, Pietro Belotti <pbelott at clemson.edu> wrote:
>
>> Hmmm I'm not sure with it.
>> If I replace
>>  sum{j in J} (y[i,j]+eps)*ur[i]*...)^r[i]
>> with
>>  sum{j in J} y[i,j]*ur[i]*...)^r[i]
>>
>> I get several warnings suggesting to enable the "halt_on_ampl_error"
>> option to see more details (nevertheless the optimal solution is
>> reached).
>> If I enable that option, couenne stops with the following error (in
>> this case r[i] == 0.355):
>>
>> couenne: halt_on_ampl_error=yes
>>
>> ANALYSIS TEST: NLP0012I
>>             Num      Status      Obj             It       time
>>         Location
>> NLP0014I             1         OPT 0.917700545.5g      785 2.121677g
>> Error evaluating objective function: can't evaluate pow'(0,0.355).
>> exit code 1
>> <BREAK>
>
> This error is returned by Ipopt while trying to compute a feasible solution
> of the continuous relaxation. However, the call to Ipopt does not have to
> terminate successfully for Couenne to work, and you can set
> halt_on_ampl_error back to no and ignore the warnings. Unfortunately AMPL
> may print many of them, but they should not prevent Couenne from finding an
> optimal solution.
>

Good to know!

Thank you very much!

-- Marco

> Pietro
>