[Cbc] I think we found a bug in cbc: How can we report it and get fixed quickly ?

Wed Sep 30 14:16:55 EDT 2015

The converted lp (used glpk to convert) contains no bounds information, 
the bounds section which appears in the lp I've sent I've put manually, 
that's why I thought that could be a bounds problem in AMPL...

On 30-09-2015 13:23, ovovis wrote:
> Wait, I am confused: You just generated the LP file out of the MPS 
> file. If the LP file contains the proper bounds, then the MPS file 
> does as well. But then AMPL properly generated the mps file. So no 
> error on the AMPL side.
>
> I am not an expert, but from this observation I would derive that cbc 
> does read lp files properly, but not mps files.
>
> Or am I mistaken here ?
>
>
>> On Sep 30, 2015, at 6:07 PM, Haroldo Gambini Santos 
>> <haroldo.santos at gmail.com <mailto:haroldo.santos at gmail.com>> wrote:
>>
>> Hi Thomas,
>>
>> I generated a LP (attached) where columns apparently related to ym 
>> variables (if I understand the .col files correctly) appear also in 
>> the BOUNDS section of the LP as being positive.
>>
>> It generated a different solution, apparently without negative values 
>> for ym variables.
>>
>> Maybe the AMPL translated model is not properly getting the bounds. 
>> What if you explicitly include
>>
>>  ym*   >= 0
>>
>> constraints into your AMPL model and test the results ?
>>
>> Cheers
>>
>> On 30-09-2015 11:49, ovovis wrote:
>>> I generated the MPS file out of AMPL. If I understand this process 
>>> correctly then the variables will be abbreviated and the .col and 
>>> .row files, that I sent you as well, are meant to translate the mps 
>>> variables into the original names. Then you should have already all 
>>> information necessary to reproduce the original names.
>>>
>>> But maybe I misunderstood your question.
>>>
>>> Please let me know.
>>>
>>> Thomas
>>>
>>>> On Sep 30, 2015, at 4:12 PM, Haroldo Gambini Santos 
>>>> <haroldo.santos at gmail.com <mailto:haroldo.santos at gmail.com>> wrote:
>>>>
>>>> Hi Thomas,
>>>>
>>>> I converted your MPS to LP to take a look (don't have AMPL here).
>>>> Strangely no "bounds" section is generated.
>>>>
>>>> The MPS conversion also lost the original names, can yon generate 
>>>> including the original names so that the specific result for 
>>>> variable ym is visible ?
>>>>
>>>> Cheers
>>>>
>>>> On 30-09-2015 10:17, ovovis wrote:
>>>>> Hi Haraldo,
>>>>>
>>>>> have you had a chance to look at the lp yet ?
>>>>>
>>>>> Would be great to hear from you. Let me know if I can be of any 
>>>>> further help.
>>>>>
>>>>> Thomas
>>>>>
>>>>>> On Sep 28, 2015, at 3:44 PM, Haroldo Gambini Santos 
>>>>>> <haroldo.santos at gmail.com> wrote:
>>>>>>
>>>>>> Hi Thomas,
>>>>>>
>>>>>> Can you send the LP where the problem occurs ?
>>>>>>
>>>>>> Cheers
>>>>>>
>>>>>> On 28-09-2015 01:37, ovovis wrote:
>>>>>>> Dear cbc team,
>>>>>>>
>>>>>>> my name is Thomas Enge from Berlin Germany. We are a small (2 
>>>>>>> persons) start up company (see also www.ovovis.de and then About 
>>>>>>> us). We use AMPL + cbc internally to provide a portfolio 
>>>>>>> optimization service to energy traders. So far we only ran tests 
>>>>>>> with our potential customers when we detected that cbc violates 
>>>>>>> the domain definition of variables in the solution for specific 
>>>>>>> problem settings. Our variables are defined as >= 0, but the 
>>>>>>> result also produces negative numbers for these variables. This 
>>>>>>> is the case for version 2.9.4 - 2.9.6.
>>>>>>>
>>>>>>> My question is how can we address this issue best to you ? And 
>>>>>>> is there a way to receive a quick fix or do we need to wait for 
>>>>>>> the next stable release ? The latter is very important for us to 
>>>>>>> understand since it effects our go-live date.
>>>>>>>
>>>>>>> Thanks in advance for your help
>>>>>>>
>>>>>>> Thomas Enge
>>>>>>>
>>>>>>>
>>>>>>> OvvvvvvvvvvvvvvvvvvvOvis
>>>>>>>
>>>>>>> ovovis GmbH
>>>>>>> Dr. Thomas Enge
>>>>>>> Stargarder Str. 57
>>>>>>> D-10437 Berlin
>>>>>>>
>>>>>>> M: +49 1515 910 5118
>>>>>>> F: +49 30 538 10 188
>>>>>>> E: tenge at ovovis.de <mailto:tenge at ovovis.de>
>>>>>>> W: www.ovovis.de <http://www.ovovis.de/>
>>>>>>> --------------------------------------
>>>>>>> Amtsgericht Charlottenburg
>>>>>>> HRB 116742B
>>>>>>> Vat-ID: DE262642185
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Cbc mailing list
>>>>>>> Cbc at list.coin-or.org
>>>>>>> http://list.coin-or.org/mailman/listinfo/cbc
>>>>>>
>>>>>> -- 
>>>>>> ==================================================
>>>>>> Haroldo Gambini Santos
>>>>>> D.Sc, Computer Science
>>>>>> Universidade Federal de Ouro Preto
>>>>>> http://www.decom.ufop.br/haroldo/
>>>>>
>>>>
>>>> -- 
>>>> ==================================================
>>>> Haroldo Gambini Santos
>>>> D.Sc, Computer Science
>>>> Universidade Federal de Ouro Preto
>>>> http://www.decom.ufop.br/haroldo/
>>>
>>
>> -- 
>> ==================================================
>> Haroldo Gambini Santos
>> D.Sc, Computer Science
>> Universidade Federal de Ouro Preto
>> http://www.decom.ufop.br/haroldo/
>> <scheduledevrel.lp.tar.gz>
>

-- 
==================================================
Haroldo Gambini Santos
D.Sc, Computer Science
Universidade Federal de Ouro Preto
http://www.decom.ufop.br/haroldo/

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