[Osi] set row solution (activities)

Ted Ralphs ted at lehigh.edu
Thu Aug 13 18:30:18 EDT 2009

In Osi, the primal solution is referred to as the column solution,
since there is one value for each column (and the dual solution is the
row solution). So I'm not sure what you meant by the "(primal) row
solution." Row activity is the inner product of the column solution
with a given row of the constraint matrix, so it is not related to the
dual solution. I assume that by setRowSolution(), you mean the method
for setting the dual solution (currently called setRowPrices(), though
for consistency, it probably shouldn't be). But this method would have
no affect on the row activities, so what do you mean by
"setRowSolution and do a memcpy into rowActivity_."?


On Thu, Aug 13, 2009 at 6:13 PM, Matthew Galati<magh at lehigh.edu> wrote:
> I think setRowPrice sets the dual solution - not the (primal) row solution.
> Internally, it is the rowActivity_ array that needs to be set - that is what
> is returned by getRowActivity(). That is why you are not seeing it come back
> - you are actually setting the duals with setRowPrice.
> I am not sure what it does to internals, but I think all you need is a
> method "setRowSolution" and do a memcpy into rowActivity_.
>> Matt,
>>        Osi.setColSolution and Osi.setRowPrice will set the column and row
>> solution, respectively.  Row activity should follow from setColSolution.
>>        Based on the Osi unit test, OsiClp ignores imposed row and column
>> solutions (at least, they are not immediately reflected in the results
>> returned
>> for row activity and reduced costs).
>>                                                Lou
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Dr. Ted Ralphs
Associate Professor, Lehigh University
(610) 628-1280
ted 'at' lehigh 'dot' edu

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