[Clp] question on gubVersion

[Fei Peng]

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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> ----------------------------------------------------------------------
>
> 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>
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>
> 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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