[Coin-discuss] OsiClp branchAndBound changes state of model

[Matthew Galati]

I changed to CbcModel. How do I get the cut timings?

On Wed, Feb 11, 2015 at 12:53 PM, Matthew Galati <matthew.galati at gmail.com>
wrote:

> Thanks John.
>
> I'll switch to CbcModel and will let you know how it goes.
>
> On Wed, Feb 11, 2015 at 10:33 AM, John Forrest <
> john.forrest at fastercoin.com> wrote:
>
>>  Matt,
>>
>> If line 1 is actually
>>
>> OsiClpSolverInterface o;
>>
>> you are in trouble anyway - OsiClpSolverInterface:branchAndBound() was
>> only written to satisfy requirements.  OsiCbcSolverInterface is also not so
>> good.
>>
>> So many things will have changed in a CbcModel after search - cutoffs,
>> number of nodes etc.  I would set up whatever cuts, heuristics and initial
>> model in CbcModel baseModel and then
>>
>> baseModel.solver()-.addRow();
>> CbcModel workingModel = baseModel;
>>     workingModel.branchAndBound();
>>
>> On another of your questions - for flexibility I would pass in a Derived
>> message handler (see for example Clp/examples/driver2.cpp) and then do
>> exactly what you want in "print".
>>
>> You can get timings for cut generators, but for strong branching you are
>> going to have to use profiling e.g. gprof.
>>
>> John Forrest
>>
>>
>> On 10/02/15 22:23, Matthew Galati wrote:
>>
>> The following workflow is not doing what I expected.
>>
>>  1 OsiClp o;
>> 2 o.loadProblem(...)
>> 3 o.branchAndBound();
>> 4 o.addRow();
>> 5 o.branchAndBound();
>>
>>  After 3, the model seems to be changed - for example, a bunch of
>> columns are fixed to 0 and some are fixed to 1. Presumably presolve or the
>> reduced model in the tree at the end of solve.
>>
>>  So, when I add my row, I am no longer working with the original model.
>>
>>  Bug? Expected behavior?
>>
>>  How does one go about doing what I want - which is: solve, add a row,
>> solve again.
>>
>>
>>
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