<br><font size=2 face="sans-serif">Kish,</font>
<br>
<br><font size=2 face="sans-serif">Thank you for finding the weakness (a
free variable entered the basis not quite as I expected). Normally
I use the standalone solver "clp" and I expect Hans Mittelmann
does as well. That is a bit more sophisticated and would probably
have changed the bounds to make it go faster.</font>
<br>
<br><font size=2 face="sans-serif">hopefully it is OK now.</font>
<br>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>Kish Shen <ks15@icparc.ic.ac.uk></b>
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<br><font size=1 face="sans-serif">Sent by: coin-lpsolver-bounces@list.coin-or.org</font>
<p><font size=1 face="sans-serif">08/20/2005 05:10 PM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td valign=top><font size=1 face="sans-serif">coin-lpsolver@list.coin-or.org</font>
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<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">Re: [Coin-lpsolver] (no subject)
(should be: possible slow solving with
CLP)</font></table>
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<br><font size=2><tt><br>
John,<br>
<br>
Thanks again for your reply!<br>
<br>
Sorry - I forgot to include a subject in my original posting, as I copied<br>
the message from a bounced mail (my original post was done in a hurry and
I<br>
mistyped the mailing list address), and forgot to put in the subject...<br>
<br>
>What driver are you using and what compiler?<br>
<br>
I have tried two ways to solve the l30 problem with Clp's dual Simplex:<br>
<br>
1)<br>
<br>
Originally I was using the OsiCbc interface, with a call to initialSolve()<br>
to solve a linear problem like l30 (and no integer columns). <br>
<br>
I simply compiled all the COIN components with the default settings, except<br>
specifying -O and without -g for compilation.<br>
<br>
I use gcc 2.3.4 linking with glibc 2.0 on Linux. The timings are done on<br>
2GHz Pentium 4 Linux boxes [I compile and run on different machines --<br>
as these 2GHz machines we have has a older gcc that has problems compiling<br>
the COIN components, but we have a dozen of them and they are faster]<br>
<br>
One possible difference is that I don't solve the MPS file directly, so<br>
the order of the rows/columns may be different from when the problem is<br>
solved from the MPS file. <br>
<br>
2)<br>
I then tried solving the problem using Clp's testit program, using the<br>
`driver' driver, again compiled with the same gcc 2.3.4 configuration.<br>
<br>
Here, with the dual solver, and solving l30 from the MPS file, Clp seems
to <br>
get into an obvious loop, here is where it seems to start:<br>
<br>
Clp0006I 7388 Obj -176.227 Primal inf 1.43572e+06 (419)<br>
Clp0006I 7389 Obj -25.5449 Primal inf 1.23023e+06 (416)<br>
Clp0006I 7390 Obj -30.2813 Primal inf 570032 (413)<br>
Clp0006I 7391 Obj 120.83 Primal inf 659060 (409)<br>
Clp0006I 7392 Obj 14.7871 Primal inf 543469 (415)<br>
Clp0006I 7393 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7395 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7396 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7398 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7399 Obj 43.6816 Primal inf 1.50536e+06 (414)<br>
Clp0006I 7400 Obj 14.7871 Primal inf 543469 (415)<br>
Clp0006I 7401 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7403 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7404 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7406 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7407 Obj 43.6816 Primal inf 1.50536e+06 (414)<br>
Clp0006I 7408 Obj 14.7871 Primal inf 543469 (415)<br>
Clp0006I 7409 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7411 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7412 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7414 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7415 Obj 43.6816 Primal inf 1.50536e+06 (414)<br>
Clp0006I 7416 Obj 14.7871 Primal inf 543469 (415)<br>
Clp0006I 7417 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7419 Obj 23.1582 Primal inf 817259 (418)<br>
Clp0006I 7420 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7422 Obj 43.9863 Primal inf 247895 (421)<br>
Clp0006I 7423 Obj 43.6816 Primal inf 1.50536e+06 (414)<br>
Clp0006I 7424 Obj 14.7871 Primal inf 543469 (415)<br>
Clp0006I 7425 Obj 23.1582 Primal inf 817259 (418)<br>
<br>
but there is no obvious loop for the original run (case 1, above, which
I<br>
left running for 2 days). For this case, I can generate the calls I<br>
made to the OSI interface, which can then be compiled separately and<br>
will hopefully reporduce the problem without using our ECLiPSe system<br>
(which is how I have bveen using OSI). Do you want me to do this and send<br>
the program to you?<br>
<br>
Cheers,<br>
<br>
Kish<br>
<br>
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