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<div class="moz-cite-prefix">Herve,<br>
<br>
preOption 12 should switch off two parts of presolve CoinDoubleton
and CoinTripleton. You can check this by running with -pOption 3
which should give printout on what actions are done in presolve.
Without preOption you should see printout like<br>
<br>
CoinPresolveDoubleton(4) - 0 rows, 0 columns dropped in time
0.004, total 0.720045<br>
CoinPresolveTripleton(8) - 0 rows, 0 columns dropped in time 0,
total 0.720045<br>
<br>
while with it set you should not see those lines.<br>
<br>
CoinPresolve failing/giving wrong answer is a bug.<br>
<br>
Can you put model (compressed) somewhere so I can download it.
Does Clp give correct result without any presolve? If not please
give me correct value of objective.<br>
<br>
John Forrest<br>
<br>
On 11/03/13 13:24, Hervé BOUVART wrote:<br>
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<div>Dear John,<br>
<br>
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I solve a large problem (470000 rows, 655000 cols), in
continuous variables (now, after numerous attempts with
integer variables).<br>
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It appears that the solution, also given by other solvers
is ok using version 2.7.7 of CLP, if I provide -preO 12 as
an option (infeasible or unbounded if presolver is used
without option).<br>
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With version 2.8, I get a solution which is 25% different!
Moreover the -preO options does not seem to help anymore.<br>
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My .MPS file is over 134 MB, so I don't attach it here.<br>
<br>
</div>
<div>What is the meaning of the figure after -preO (presolve
options) command?<br>
<br>
</div>
<div>I use CLP and CBC compiled via MS Visual C++ 2010 Express.<br>
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<div>Thanks in advance,<br>
<br>
</div>
<div>Herve<br>
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