[Cbc] change matrix coefficient at coin-cbc.

[Stefan Vigerske]

Hi,

OsiCbc is a bad choice for accessing Cbc, because it gives only poor 
performance and is not really maintained anymore.

A more efficient way that gives you performance close to the standalone 
binary is to use the CbcSolver interface as shown in 
Cbc/examples/driver4.cpp.

For that, you create your MIP in an OsiClpSolverInterface lp and then 
solve it by Cbc via

const char* args[] = { "mybin", "-solver", "-quit" };

CbcModel* model = new CbcModel(lp);
CbcMain0(model);
CbcMain1(3, args, *model);


OsiClpSolverInterface implements getMutableMatrixByCol, which should be 
sufficient.

Hope this helps,
Stefan


On 09/06/2012 07:56 PM, Ivan Meireles Costa wrote:
> oh, sry.
>
> the lp declaration is:
>
> OsiCbcSolverInterface *lp;
>
> On Thu, Sep 6, 2012 at 2:49 PM, Ivan Meireles Costa <ivan.costa at gapso.com.br
>> wrote:
>
>> Hi guys,
>>
>> I'm working on my first project with coin-or cbc and have one problem to
>> change a coefficient in the matrix in my OsiCbcSolverInterface.
>> I've tried:
>>
>> bool OPT_COIN::chgCoef( int row, int col, double newcoef )
>> {
>>      bool ret = true;
>>      CoinPackedMatrix *matrix = lp->getMutableMatrixByRow();
>>
>>
>>
>>      if(matrix == NULL)
>>      {
>>          printf("\n\n\nNULL\n\n\n");
>>      }
>>      matrix->modifyCoefficient(row, col, newcoef);
>>
>>
>>      return ret;
>> }
>>
>> but the method "getMutableMatrixByRow()" is not yet implemented, it return
>> NULL.
>>
>> thanks
>>
>>
>>
>>
>> --
>> *Ivan Meireles Costa*
>> *Estágiario em otimização*
>>   *Telefone:* 31 3508-1323
>>   *Celular:* 31 9869-6987
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>> da complexidade.
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>> futuro.
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>>
>
>
>
>
>
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