[Coin-discuss] Inconsistency between Osi Solves

[Ted Ralphs]

As far as I remember, the branchAndBound() method of Clp is a fairly 
basic implementation that is not really intended for practical use. You 
probably want to compare with OsiCbc for solving integer programs. It 
should give better results.

Cheers,

Ted

Pedro Teixeira wrote:
> Hi,
> 
> I am new to coin-or and not sure if this is the appropriate list to
> post. I'm getting very different solutions when using the same model
> but switching from OsiClpSolverInterface and OsiSymSolverInterface.
> 
> my current usage is simple:
> 
> si->loadFromCoinModel(model , true);
> si->initialSolve();	
> si->branchAndBound();
> 
> With ClpSolver, it takes much more time and I get (for illustration):
> Search took 43600 iterations and 7302 nodes
> Clp0000I Optimal - objective value 115
> 
> However, with SymSolver I get the result instantaneously:
> Solution Found: Node 1, Level 1
> Solution Cost: 10.000
> 
> Shouldn't I get the same results? Or is there any known issues with Osi?
> Can anyone shed in any light?
> 
> cheers,
> Pedro
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-- 
Dr. Ted Ralphs
Associate Professor
Industrial and Systems Engineering
Lehigh University
(610)758-4784
ted at lehigh dot edu
coral.ie.lehigh.edu/~ted