[Coin-discuss] OsiCbcSolverInterface turn off log messages

[Tim Hultberg]

Yes, but even though I am interfacing with the abstract Osi interface in
flopc++, a user must still choose a concrete solver and can set solver
specific hints via Osi. As for example

MP_model m(new OsiCpxSolverInterface);
m->setIntParam(OsiMaxNumIteration,2); //or whatever

If I understood John correctly, the problem with OsiCbc is that it
delegates
the methods to the underlying LP solver which is not necessarily Clp and
might
even be unknown to the application. Therefore I support your proposal to
let
OsiClp:brachAndBound() invoke Cbc (with Clp as underlying LP solver)

Tim

>>> Ted Ralphs <tkralphs at lehigh.edu> 03/09/07 7:22 PM >>>
But this is the case for all solvers when called through Osi. The Osi is
basically for users who are willing to give up a little flexibility in
how they interact with the underlying solver in order to have a standard
API and the ability to switch solvers easily. Even notwithstanding the
more limited interface, any code written to work with multiple solvers
is going to suffer some loss of performance. Most users just want to run
with defaults and will find this tradeoff worthwhile. If someone really
wants to fine-tune the solver and performance is absolutely paramount,
OSI may not be a good choice.

Ted

John J Forrest wrote:
> 
> The reason I dislike OsiCbc is that it uses other OsiXxx solvers so
> there is no clean structure.  If you do
> OsiCbcSolverInterface::branchAndBound it calls Cbc's branch and bound
> which uses a OsiXxxSolverInterface solver.  To make things even worse
> this underlying solver could be OsiCbcSolverInterface!! (eventually a
> real solver would be called).
> 
> Also it is difficult to tune as apart from CbcStrategy it only has
> OsiXxxSolverInterface methods.
> 
> The status of OsiCbc will always be - it will work - but it will not
> easily take advantage of new ideas in Cbc or tuning parameters.
> 
> John Forrest


-- 
Dr. Ted Ralphs
Associate Professor
Industrial and Systems Engineering
Lehigh University
(610)758-4784
tkralphs at lehigh.edu
www.lehigh.edu/~tkr2
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