[Coin-discuss] How to choose a MIP solver in GLPK OSI?

[Tim Hultberg]

You can downcast to a specific osi solver interface from flopc++ like
this: 

"This is the (not very sexy) way to set the relative termination
tolerance in Flopc++/CBC
dynamic_cast<OsiCbcSolverInterface
*>(MP_model::getDefaultModel().operator->())->getModelPtr()->setAllowableGap(0.1);"

Tim

>>> Michal Kaut <mail at michalkaut.net> 18/06/2007 11:56 >>>
Hello,

I have a MIP problem that GlpSol with "--intopt" solves in 0.2 seconds,

but won't solve at all without the option  (I let it run over the 
weekend, it did not even find a feasible solution...)

Unfortunately, using GLPK OSI uses the old/original lpx_integer() 
method, which is equivalent to running glpsol without parameters - and

hence useless for my problem.
Is there a way (in OSI) to use lpx_intopt() instead of lpx_integer(), 
other than rewriting OsiGlpkSolverInterface::branchAndBound() and 
re-compiling OSI?

I found a discussion on coin-osi-devel from March 2006:
http://list.coin-or.org/pipermail/coin-osi-devel/2006-March/000002.html

Has anything changed since then? I really believe that it is important

that OSI has some (preferably simple-to-use) interface to 
solver-specific options.

Note: In the discussion, they mention downcasting/direct call of the 
GLPK function. Would it work also from FlopCpp? If so, could someone 
show me how?


Thanks a lot in advance.


Regards,
Michal Kaut
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