<br>thank you, Ashutosh!<br>at least, I know it's really my bug now :)<br><br>[]'s<br>Pedro<br><br><div class="gmail_quote">On Feb 7, 2008 11:18 PM, Ashutosh Mahajan <<a href="mailto:asm4@lehigh.edu">asm4@lehigh.edu</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">pedro,<br> the optimal solution to the mps file posted seems to be 10. i tried with<br>cplex, xpress, symphony, cbc and even clp (branch and bound).<br>
some valid constraints may be missing from your model.<br><br>ashutosh<br><div class="Ih2E3d"><br>On Thu, 07 Feb 2008, Pedro Teixeira wrote:<br><br>> The situation is as follows (I'm running the latest stable of all<br>
> projects, should I be running from the trunk?) :<br>><br>> Both Cbc and Sym give the same straight objetive value of 10. Where for<br>> this instance the known optimal is 85. The strange thing is that with Clp,<br>
> the first result is 110 but then I add an extra cut (subtour) and it<br>> becomes infeasible...<br>><br>> It's really probably something in my code, but it seems Clp was closer to<br>> what I wanted.. I posted the issue here because I was surprised to get<br>
> different solutions. I'm also trying to run in cplex, but as you suggested<br>> I'll stick with Cbc and Sym, disregard Clp and will review the code again<br>> :/<br>><br>> Ashutosh, I copied the model here:<br>
</div>> [1]http://www.pedro.not.br/tmp/model.mps<br><div class="Ih2E3d">><br>> thanks for the replies.<br>> Pedro<br>><br></div><div><div></div><div class="Wj3C7c">> On Feb 7, 2008 1:20 PM, Ted Ralphs <[2]ted@<a href="http://lehigh.edu" target="_blank">lehigh.edu</a>> wrote:<br>
><br>> As far as I remember, the branchAndBound() method of Clp is a fairly<br>> basic implementation that is not really intended for practical use. You<br>> probably want to compare with OsiCbc for solving integer programs. It<br>
> should give better results.<br>><br>> Cheers,<br>><br>> Ted<br>> Pedro Teixeira wrote:<br>> > Hi,<br>> ><br>> > I am new to coin-or and not sure if this is the appropriate list to<br>
> > post. I'm getting very different solutions when using the same model<br>> > but switching from OsiClpSolverInterface and OsiSymSolverInterface.<br>> ><br>> > my current usage is simple:<br>
> ><br>> > si->loadFromCoinModel(model , true);<br>> > si->initialSolve();<br>> > si->branchAndBound();<br>> ><br>> > With ClpSolver, it takes much more time and I get (for illustration):<br>
> > Search took 43600 iterations and 7302 nodes<br>> > Clp0000I Optimal - objective value 115<br>> ><br>> > However, with SymSolver I get the result instantaneously:<br>> > Solution Found: Node 1, Level 1<br>
> > Solution Cost: 10.000<br>> ><br>> > Shouldn't I get the same results? Or is there any known issues with<br>> Osi?<br>> > Can anyone shed in any light?<br>> ><br>
> > cheers,<br>> > Pedro<br>> > _______________________________________________<br>> > Coin-discuss mailing list<br></div></div>> > [3]Coin-<a href="mailto:discuss@list.coin-or.org">discuss@list.coin-or.org</a><br>
> > [4]http://list.coin-<a href="http://or.org/mailman/listinfo/coin-discuss" target="_blank">or.org/mailman/listinfo/coin-discuss</a><br><div class="Ih2E3d">><br>> --<br>> Dr. Ted Ralphs<br>
> Associate Professor<br>> Industrial and Systems Engineering<br>> Lehigh University<br>> (610)758-4784<br>> ted at lehigh dot edu<br></div>> [5]coral.ie.lehigh.edu/~ted<br>
><br>> References<br>><br>> Visible links<br>> 1. <a href="http://www.pedro.not.br/tmp/model.mps" target="_blank">http://www.pedro.not.br/tmp/model.mps</a><br>> 2. mailto:<a href="mailto:ted@lehigh.edu">ted@lehigh.edu</a><br>
> 3. mailto:<a href="mailto:Coin-discuss@list.coin-or.org">Coin-discuss@list.coin-or.org</a><br>> 4. <a href="http://list.coin-or.org/mailman/listinfo/coin-discuss" target="_blank">http://list.coin-or.org/mailman/listinfo/coin-discuss</a><br>
> 5. <a href="http://coral.ie.lehigh.edu/%7Eted" target="_blank">http://coral.ie.lehigh.edu/%7Eted</a><br><div class="Ih2E3d"><br>> _______________________________________________<br>> Coin-discuss mailing list<br>
> <a href="mailto:Coin-discuss@list.coin-or.org">Coin-discuss@list.coin-or.org</a><br>> <a href="http://list.coin-or.org/mailman/listinfo/coin-discuss" target="_blank">http://list.coin-or.org/mailman/listinfo/coin-discuss</a><br>
<br><br>--<br></div><div><div></div><div class="Wj3C7c">regards<br>Ashutosh Mahajan<br><a href="http://www.lehigh.edu/%7Easm4" target="_blank">http://www.lehigh.edu/~asm4</a><br><br></div></div><br>-----BEGIN PGP SIGNATURE-----<br>
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