[Coin-discuss] problem with CLP

[mathieu lacroix]

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