[BCP] Antw: Re: Primal and dual solution are not the same

[Andrea Trautsamwieser]

Currently I am using Clp. But I also tried it with Xpress. It doesn't matter. I am using Bcp-1.2.3 and Bcp-1.3.4.

Andrea

>>> Sepehr Nemati Proon  12.08.12 14.21 Uhr >>>

Which solver are you using?
 
Sepehr NP

 
On Fri, Aug 10, 2012 at 7:24 AM, Andrea Trautsamwieser <andrea.trautsamwieser at boku.ac.at> wrote:
Hi,
 
I want to use the dual variables for improving my algorithm, However, I found out that the dual solution does not equal the primal solution in each node, although it should. 
 
The termcode of the BCP_lp_result is 2, so it should be solved to optimality. I have tried to solve small test instances to check the error, however I have not find out what is going wrong exactly.
 
The primal solution contains some of the new generated variables, but not all of the dual variables are adapted accordingly. It seems that the dual neglects at least one of the new algorithmic variables and so I obtain different objective values and the algorithmic variable is generated again in the next column generation iteration.
 
Has anyone any idea to that problem?
 
Thank you very much,
 
Andrea
 


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-- 
Sepehr Nemati
PhD Student
Department of Industrial Engineering
University of Pittsburgh

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