[Coin-discuss] OsiClpSolverInterface error when enableSimplexInterface=true

[John J Forrest]

enableSimplex is a bit delicate as it expects the user to be deciding 
which variable is going to come in.  You will see an example in 
OsiSimplexInterfaceTest.cpp.  If you just say the interface is enabled but 
don't  take charge then the code will update the reduced costs but then in 
choosing the next column it will update them again as that bit of code 
does not know about enableSimplex..

I can fiddle with interface but I would feel it to be more useful to make 
it more rugged when  enableSimplex is being used with user intervention.

John Forrest



"Fanie Terblanche" <RKWSET at puknet.puk.ac.za> 
Sent by: coin-discuss-admin at www-124.southbury.usf.ibm.com
03/02/2004 09:11 AM
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[Coin-discuss] OsiClpSolverInterface error when 
enableSimplexInterface=true






Hi,

I've recently started looking at the OsiClpSolverInterface code. I
experienced some problems when enabling the simplex interface. Perhaps
there is someone that knows the code well enough to sort out the problem
within reasonable time. I could give it a go......but rather let me ask
the experts!!  Below is a small sample using exmip1.mps as input.

OsiClpSolverInterface solver1;
  int mpsReadError = solver1.readMps(argv[1]);
  assert(mpsReadError == 0);
  solver1.setHintParam(OsiDoScale,false,OsiHintDo);
  solver1.setHintParam(OsiDoPresolveInInitial,false,OsiHintDo);
  solver1.setHintParam(OsiDoDualInInitial,false,OsiHintDo);
  solver1.setHintParam(OsiDoPresolveInResolve,false,OsiHintDo);
  solver1.setHintParam(OsiDoDualInResolve,false,OsiHintDo);
  solver1.enableSimplexInterface(true);
  solver1.initialSolve();

When executing the above code the following assertion fails
ClpSimplexPrimal::pivotResult line 2146
assert (fabs(dj_[sequenceIn_])<1.0e-6);

Regards





Fanie Terblanche
School of Computer, Statistical, and Mathematical Sciences
North West University (Potchefstroom Campus)
Tel:   +27 (0)18 299 2536
Fax:  +27 (0)18 299 2557
www.puk.ac.za





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