[Cbc] Question about "**" prefix in CBC solution file lines

[John Forrest]

Jean-Paul,

How infeasible?

The most likely explanation is that when scaled the problem was feasible 
within tolerance, but when the solution was unscaled it violated a 
tolerance.  Clp would have reported that as optimal but with a secondary 
status flag set.  OsiSolverInterface would drop that information.  Why 
this happens so rarely is odder.

John

On 03/04/12 04:40, Watson, Jean-paul wrote:
> I just encountered our first Coopr user that has generated models such 
> that the resulting CBC solution files contain rows for variable lines 
> that are prefixed by "**".
>
> When I look at the code (CBCGenSolution.cpp), it is obvious that the 
> "**" indicate -- in the case of variables -- that the bounds have been 
> violated for this particular variable.
>
> This makes sense for a brief moment, until I realize that CBC is 
> reporting the solution is optimal. Solutions can of course violate 
> strict bounds when tolerances are considered, but I would assume I 
> would see this behavior on any of the numerous other models we have 
> solved with CBC.
>
> Can anyone shed some light on this condition, and how the resulting 
> solution should be interpreted?
>
> Thanks,
>
> Jean-Paul
>
>
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