[Clp] question on gubVersion

[John Forrest]

Fei,

GUB has not been well tested for some time.  If you can send me an 
example and driver that fails, I will take a look at it.

John Forrest

On 09/05/14 20:51, Fei Peng wrote:
> Hi John,
>
> I've been reading/trying the code related to gubversion for a couple 
> of days now. The gub solve sometimes runs without any problem, but 
> quite frequently the first primal() run with DynamicMatrix fails (with 
> obj -nan and primal inf inf). Can you give some pointers as to where 
> to start looking?
>
> Thanks
> Fei
>
>
> On 2014-05-08 12:00 PM, clp-request at list.coin-or.org wrote:
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>>    1. Re: question on gubVersion (John Forrest)
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>> ----------------------------------------------------------------------
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>> Message: 1
>> Date: Wed, 07 May 2014 18:24:37 +0100
>> From: John Forrest <john.forrest at fastercoin.com>
>> To: clp at list.coin-or.org
>> Subject: Re: [Clp] question on gubVersion
>> Message-ID: <536A6C55.1070909 at fastercoin.com>
>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>>
>> Fei,
>>
>> gubVersion returns a shrunken model with the matrix type
>> ClpDynamicMatrix which has the extra rows and columns and the idea is
>> that primal will then use that in a gub style algorithm.  You may find
>> it easier to look at the gub examples in Clp/examples.
>>
>> I would not be surprised if something has got broken - but that can be
>> fixed.
>>
>> Give Richard Van Slyke credit as well as George Dantzig  - I think GUB
>> was being developed at Berkeley when I was doing a Masters there!
>>
>> John Forrest
>>
>>
>> On 07/05/14 16:23, Fei Peng wrote:
>>> Hello clp community,
>>>
>>> I have a question about the routine resolveGub and gubVersion included
>>> in osiClpSolverInterface and clpSimplexOther, respectively. I
>>> was thinking that this implements the GUB simplex by Dantzig, but it
>>> seems like gubVersion only shrinks the model, gives the model back to
>>> the solverinterface and let it do primal()? maybe I'm not reading it
>>> careful enough but could someone advise if this is what it's supposed
>>> to do?
>>>
>>> Thanks!
>>> Fei
>>>
>>>
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