[Coin-discuss] OSI, CLP pivot

[John J Forrest]

Matt,

If you want to keep to an OsiSolverInterface then I probably can't help,
but if you know you will be using OsiClpSolverInterface then I may be able
to help.  If you can put together a driver to go through the steps you want
then I can see how much faster I can make it - either by adding calls using
the Clp getModelPtr() or more elegantly by adding a new specialOption bit
to OsiClpSolverInterface.

John


                                                                           
             Matthew Galati                                                
             <magh at lehigh.edu>                                             
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If someone wants to do the following, using the "simplex interface":
{
  while{
     //some stuff...
     ...
     si->resolve();
     si->pivot(colIn, colOut, outStatus);
     ...
     si->getBasisStatus();
     si->getBInvARow( );
     ...
     //some stuff...
  }
}

Is it neccessary to call enable/disableSimplexInterface at every call?

I noticed, that if you pivot, the "basis_" is not updated until
disableSimplexInterface is called. So, the next call to getBasisStatus
does not have updated status.

The following seems to work, but is very slow. There is alot of time
spent in enable/disable.

{
  while{
     //some stuff...
     ...
     si->resolve();
     si->enableSimplexInterface();
     si->pivot(colIn, colOut, outStatus);
     si->disableSimplexInterface();
     ...
     si->enableSimplexInterface();
     si->getBasisStatus();
     si->disableSimplexInterface();

     si->enableSimplexInterface();
     si->getBInvARow( );
     si->disableSimplexInterface();
     ...
     //some stuff...
  }
}

Thanks,
Matt


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