[Osi] [Clp] set row solution (activities)
lou at cs.sfu.ca
Thu Aug 20 17:06:31 EDT 2009
Laci, et al.,
My take on this is that nothing new is needed in OSI. A correctly
functioning OsiXXX should reflect the most recent valid primal or dual solution
when asked for row activity or reduced costs, whether the solution was obtained
from the solver or imposed by the user. It's simply a bug if this doesn't
In an earlier email to Matt G. (which I didn't post to the list), I was
pointing out that this isn't quite as simple as it sounds. There are multiple
1) When an OsiXXX object is created, it's expected to construct some sort of
2) The user can impose a solution.
3) The solver can supply a solution.
It's also possible changes have been made to the problem (coefficients, bounds,
rhs, costs) so that the solution may no longer be valid. From memory, the OSI
spec is not clear about what should happen in this case, and it's something that
we should specify.
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