[Coin-lpsolver] Parametric Analysis using CLP + OSI

[Paulo J. S. Silva]

Ops...

I am still having problems with the parametric analysis code. It looks
like John changes to primalPivotResult still don't refresh everything
needed.

For now my code may face numerical problems if I update the objective
function before primalPivotResult. After many pivots the function is
changing a little the reduced costs (it should remain the same as I said
in the last e-mail). The difference is up to 1.0e-8, but this is enough
for the code to detected incorrectly unboundedness of the problem.

If I move the objective function after the primalPivotResult everything
works. It also work if I leave the objective update before the pivot
function but call

s.disableSimplexInterface()
s.enableSimplexInterface(True)

after the pivot. I believe this two calls refresh some data.

Unfortunately, I have to give a seminar in two days and I still don't
have the slides. So I wont be able to work for two days on this. When I
come back I'll look at the paraobj code John added to the unit tests to
see if I can reproduce the error my reading the MPS file with the
problem description.

Best,

Paulo

-- 
Paulo José da Silva e Silva 
Professor Assistente do Dep. de Ciência da Computação
(Assistant Professor of the Computer Science Dept.)
Universidade de São Paulo - Brazil

e-mail: pjssilva at ime.usp.br        Web: http://www.ime.usp.br/~pjssilva

Teoria é o que não entendemos o    (Theory is something we don't)
suficiente para chamar de prática. (understand well enough to call) 
                                   (practice)