[Coin-discuss] problem with CLP

[mathieu lacroix]

Hi,
I am sorry. I have not tried with the latest version of Clp. It seems ok 
with the latest.
Best regards,
Mathieu


John J Forrest wrote:

>Mathieu,
>
>Sounds like a bug in Clp to me.
>
>To get round it try your suggestion - very little overhead in copying but
>you will be starting from an all slack basis which may be slower if more
>reliable.  Or just use getModelPtr()->allSlackBasis which should give same
>effect.
>
>To help debug - try using getModelPtr()->saveModel as well as writing mps
>file.  Then see if it has problems using restoreModel.  If so send me the
>file.
>
>John Forrest
>
>
>                                                                           
>             mathieu lacroix                                               
>             <mathieu.lacroix@                                             
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>                                       [Coin-discuss] problem with CLP     
>                                                                           
>             09/08/06 03:22 AM                                             
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>
>Hi,
>I develop a branch and cut algorithm with BCP for a metric constraint
>based formulation. To separate metric constraints, I solve a linear
>program (wich is totally different from the linear relaxation of the
>integer linear program I want to solve) with an Osi/Clp object. In each
>separation, only the objective function is changed in this linear
>program. Sometimes, a bug appears in the resolution of the metric
>separation linear program : whether the resolution takes a long time
>(more than 10 minutes) or it does not terminate (I had to kill it after
>1000 minutes of computation whereas the limit time is 300 minutes).
>However, for each of these linear programs which make troubles, if I
>solve it using Osi/CLP (by reading the mps file and using the osi
>example "basic" for instance), it takes less than 10 seconds to solve
>it. I guess the bug comes from the fact that the Osi object is not in
>the same state after one resolution. Is there any solution for the
>problem different than creating the linear program at each iteration (I
>have not yet tried this solution)?
>
>Best regards,
>Mathieu
>
>--
>Mathieu LACROIX
>mathieu.lacroix at isima.fr
>Université Blaise Pascal - Clermont Fd II
>Laboratoire LIMOS
>Bâtiment ISIMA - Bureau D112
>Complexe scientifique des Cézeaux
>63 177 Aubière, Cedex - France
>Tel : 04.73.40.79.48
>Fax : 04.73.40.76.39
>
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-- 
Mathieu LACROIX
mathieu.lacroix at isima.fr
Université Blaise Pascal - Clermont Fd II
Laboratoire LIMOS
Bâtiment ISIMA - Bureau D112
Complexe scientifique des Cézeaux
63 177 Aubière, Cedex - France
Tel : 04.73.40.79.48
Fax : 04.73.40.76.39