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<div class="moz-cite-prefix">Nicolas,<br>
<br>
I am unable to reproduce the errors (on linux).<br>
<br>
Crash.lp says it is infeasible - even just using clp to solve
continuous. With scaling it says there is an infeasibility of
5.0e-5 while with scaling off there are two summing to 0.002 which
might be easier to track down. I suspect tiny infeasibilities are
the reason you got the messages with preprocessing.<br>
<br>
If you can track down infeasibility, it may be worth adding extra
variables or relaxing rhs to keep feasible - and then you might be
able to go back to using preprocessing.<br>
<br>
Erreur.lp looks alright (although coefficients of -1.0e15 are not
healthy - but I think they transfer to objective).<br>
<br>
John Forrest<br>
On 06/07/16 16:01, <a class="moz-txt-link-abbreviated" href="mailto:nicolas.derhy@engie.com">nicolas.derhy@engie.com</a> wrote:<br>
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<p class="MsoNormal"><span lang="EN-US">Hi everyone,<br>
<br>
I want to report problems with CBC when I disable
preprocessing.</span></p>
<p class="MsoNormal"><span lang="EN-US">The version I use is CBC
2.9.8 (x86) on Win7.
</span></p>
<p class="MsoNormal"><span lang="EN-US">In the command line, I
add “-ratio 0.05 -seconds 30” (for example : cbc "Crash.lp"
-ratio 0.05 -preprocess off -seconds 30 -solve
-printingOptions all -solution "solution_crash.txt")</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I have attached two
files :</span></p>
<p class="MsoListParagraph"><span lang="EN-US"><span>-<span>
</span></span></span><span lang="EN-US">Crash.lp : CBC
stops suddenly</span></p>
<p class="MsoListParagraph"><span lang="EN-US"><span>-<span>
</span></span></span><span lang="EN-US">Error.lp : first,
it seems optimization was completed successfully. But the
objective function is clearly wrong and when I export
solution, optimal value of some binary variables are non
integer (vDebitNul(Interco_0,Noeud_9,Noeud_2) = 0.168948)</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I tried to modify some
parameters (preprocess, presolve) but nothing works.</span></p>
<p class="MsoNormal"><span lang="EN-US">If I activate
preprocessing, everything works.
</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I disabled preprocessing
previously because I obtained weird results and could not
use optimal solution provided by CBC in some cases. I
noticed CBC generated the following message :</span></p>
<p class="MsoNormal"><span lang="EN-US">“Cgl0013I Postprocessed
model is infeasible - possible tolerance issue - try without
preprocessing”</span></p>
<p class="MsoNormal"><span lang="EN-US">So, it was the reason
for disabling preprocessing. After that (and until these new
problems), everything worked better.</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">If anyone has an idea to
improve stability of CBC when preprocess is off, it would be
great.</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">Nicolas</span></p>
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