[Cbc] Fwd: please help

[Christos]

Thank you for your suggestion, i will check it and let you know.

But i think the problem is elsewhere.
When i solve the same problem with gams via cbc solver it takes 30-60 
seconds, and not 60 minutes!
Why?

On 4/10/2012 17:57, Haroldo Santos wrote:
> On Thu, Oct 4, 2012 at 6:41 AM, Christos <chtsolak at gmail.com 
> <mailto:chtsolak at gmail.com>> wrote:
>
>     I am asking you because i have a big problem. With very small
>     alteration in data operation time goes from 9' to 65' !!!
>
> This is  expected when solving Integer Programs if you are willing to 
> proof the optimality.
> One thing you can do to exit more quickly, if you do not need the 
> optimal solution (a good one may be enough), is to force the solver to 
> quit after finding some solutions with the maxSolutions paramater.
>
>
>     Any recommendations on the way i solve the model?
>     Do you think that the above times are normal for such a model?
>
>
>
>     -------- Original Message --------
>     Subject: 	please help
>     Date: 	Wed, 03 Oct 2012 13:13:03 +0300
>     From: 	Christos <chtsolak at gmail.com> <mailto:chtsolak at gmail.com>
>     To: 	cbc at list.coin-or.org <mailto:cbc at list.coin-or.org>
>     <cbc at list.coin-or.org> <mailto:cbc at list.coin-or.org>
>
>
>
>     Hi all,
>
>     i am a student in the final phase of the Milp model which i want
>     to solve.
>
>     So, i have a milp model
>     columns: 46614
>     integers:  12540 (binary)
>     rows:        40842
>     nonzeros:117823
>
>     I tried these simple methods
>     1.
>     /solver1.loadProblem(numcols, numrows, start, index, value, collb,
>     colub, obj, rowlb, rowub);
>     solver1.initialSolve();
>     solver1.branchAndBound() ;/
>     2.
>     /solver1.loadProblem(numcols, numrows, start, index, value, collb,
>     colub, obj, rowlb, rowub);
>     CbcModel model(solver1);
>     CbcMain0(model);
>     const char * argv2[]={"DAS","-solve","-quit"}; /-> _i don't know
>     what this do._/
>     CbcMain1(3,argv2,model);
>
>     /Since i am an amateur, can you help me?
>     What method should i use to solve the model? 1,2 or something else?
>     Any recommendations?
>
>     The 1st takes an hour and stops.
>     The 2nd takes either 8' or 35' depending on the data.
>
>     Your help is much appreciated.
>
>     Christos
>
>
>
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>
>
>
> -- 
> =============================================================
> Haroldo Gambini Santos
> Computing Department - Universidade Federal de Ouro Preto - UFOP
> email: haroldo [at ] iceb.ufop.br <http://iceb.ufop.br>
> home/research page: www.decom.ufop.br/haroldo/ 
> <http://www.decom.ufop.br/haroldo/>
>
> "Computer science is no more about computers than astronomy
> is about telescopes." Edsger Dijkstra
>

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