<div dir="ltr"><div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr">El dom., 6 ene. 2019 a las 13:27, John Forrest (<<a href="mailto:john.forrest@fastercoin.com">john.forrest@fastercoin.com</a>>) escribió:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div class="gmail-m_-5057512837296354997moz-cite-prefix">If you update Cbc stable and add</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix"><br>
</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix"> -DKEEP_ORIGINAL_SOLVER</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix"><br>
</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix">to CXXDEFS in configure then solver
will stay same.</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix"><br>
</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix">Remember that the bounds on integer
variables will have been changed to give an integer solution.</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix"><br>
</div>
<div class="gmail-m_-5057512837296354997moz-cite-prefix">John Forrest<br>
</div>
</div></blockquote><div><br></div>Thank you John! You were really fast to take care of my question. But I think this solution is not the ideal to me, since before use Muriqui Optimizer, users would have to install CBC by themselves, and probably they will not use -DKEEP_ORIGINAL_SOLVER. <br><br>>From my point of view, it would be better if there were a parameter in CbcModel to be set. For example, if I would set a hypothetical parameter CbcKeepOriginalSolver to 1, the original solver is kept. Or maybe a method in CbcClass to set this behavior, like this:<br><br>void keepOriginalSolver (bool value);<br><br>Thanks for your attention.<br><br>Wendel Melo<div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div bgcolor="#FFFFFF">
<div class="gmail-m_-5057512837296354997moz-cite-prefix">On 05/01/2019 23:12, Wendel Melo wrote:<br>
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<blockquote type="cite">
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<div dir="ltr">Dear friends<br>
<br>
I am giving my first steps with CBC to Mixed Integer Linear
Programming (MILP) by means of the C++ API. My current goal is
to turn Cbc one of the MILP solvers supported in Muriqui
Optimizer, a free MINLP solver (<a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.wendelmelo.net_software&d=DwMDaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=AEWIZiNSSlppb_jyQKA8GtHkg2N4WiI7Ya5btonYBgA&m=vF3oHShdseEsl9rfkG3oDqswH4nxi3dKxBlIUpKfP9I&s=Xab9Z8MBD4MYd7iPauJrXypCU1gGdGvKVvcivCdX9OM&e=" target="_blank">www.wendelmelo.net/software</a>).<br>
<br>
Due to design questions, I have been constructing an object of
the CbcModel class using an empty OsiSolverInterface object:<br>
<br>
OsiClpSolverInterface clp ;<br>
CbcModel *model = new (std::nothrow) CbcModel(clp);<br>
<br>
After that, I have been set the coefficients of my MILP
problem by means of the pointer returned by the method
CbcModel::solver, for example:<br>
<br>
OsiSolverInterface *solver = model->solver()<br>
<br>
solver->addCol(0, NULL, NULL, 0.0, 1000.0, 1.0);<br>
<br>
I am performing in this way to avoid delay copping the
OsiSolverInterface object in the CbcModel constructor since I
need to solve a sequence where the same MILP problem has to be
solved several times just changing some parameters.<br>
<br>
But I have been getting some problems. After calling method
CbcModel::branchAndBound by the second time, the pointer
returned by CbcModel::solver is getting a different value of
the previous call, for example:<br>
<br>
std::cout << "before BB solver pointer: " <<
model->solver() << std::endl;<br>
model->branchAndBound()<br>
std::cout << "after BB solver pointer: " <<
model->solver() << std::endl;<br>
<br>
The code above prints:<br>
<br>
before BB solver pointer: 0x1455a628<br>
after BB solver pointer: 0x14887f88<br>
<br>
So, we can see the solver pointer in CbcModel object was
changed. Why is it happening? I believe creating new solver
objects is bad because increase the computations. Is there a
way to avoid the changing of solver object pointer? Are there
other methods in CbcModel that can provoke the changing of the
solver pointer?<br>
<br>
Thanks in advanced<br>
<br>
Best regards<br>
<br>
<br>
Wendel Melo<br>
<a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.wendeldelo.net&d=DwMDaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=AEWIZiNSSlppb_jyQKA8GtHkg2N4WiI7Ya5btonYBgA&m=vF3oHShdseEsl9rfkG3oDqswH4nxi3dKxBlIUpKfP9I&s=bS4fzYTpGhS1fjOrU5uvoQyqlePAhVZ612Mm_CJ_rZA&e=" target="_blank">www.wendeldelo.net</a><br>
</div>
</div>
<br>
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</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="gmail_signature">Wendel</div></div></div>