[Clp] How to get integral solution for totally unimodular matrix?

[Lasse Kliemann]

John, it's essentially the code you sent me, just with some 
additional output for debugging. It appears however that despite 
this warning message

   Clp3002W Empty problem - 250 rows, 0 columns and 0 elements

the problem is solved correctly. I also integrated your extra 
code in my main application, and it works fine.

These two:

   si->getModelPtr()->numberRows()
   si->getModelPtr()->numberColumns()

also show correct numbers.

The only obvious problem left is that warning message itself, 
which can be irritating.


* Message by -John J Forrest- from Thu 2009-06-25:
> 
> Lasse,
> 
> I don't see that the changes I suggested would cause that.  Try just
> replacing initialSolve by resolve - also print out size of model before
> resolve.  If you want to send me stuff directly do so (as long as it is not
> too large).
> 
> John Forrest
> 
> 
>                                                                        
>   From:       Lasse Kliemann <lasse-list-coin-2009 at mail.plastictree.net>
>                                                                        
>   To:         clp at list.coin-or.org                                     
>                                                                        
>   Date:       06/24/2009 02:53 PM                                      
>                                                                        
>   Subject:    Re: [Clp] How to get integral solution for totally unimodular matrix?
>                                                                        
> 
> 
> 
> 
> 
> * Message by -John J Forrest- from Wed 2009-06-24:
> 
> > If you replace the initialSolve by resolve, then the problem goes away.
> > However the long thin strategy is 50 times faster!
> >
> > To get good performance and normal simplex characteristics you need to
> add
> > ten lines.  I attach a modified integral.cpp.
> 
> Thank you, John, for the explanation and the example code.
> 
> I ran it, but it keeps complaining about an empty problem:
> 
>    Clp3002W Empty problem - 250 rows, 0 columns and 0 elements
> 
> The problem *is* loaded via 'assignProblem'; I also tried:
> 
>    si->getModelPtr()->loadProblem(*matrix, col_lb, col_ub,
>         objective, row_lb, row_ub);
> 
> to no avail.
> 
> 
> Thank you for a hint.
> Lasse
> [attachment "atthbeby.dat" deleted by John J Forrest/Watson/IBM]
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