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<body class='hmmessage'><div dir='ltr'><font face="Calibri,sans-serif" size="3" style="font-size:12pt;" color="#000000"><br id="FontBreak"></font>Hi Rodolfo,<div><br></div><div>Thank's for reply.</div><div><br></div><div><div>But when applying pricing, we use dual values to get the reduced cost,</div><div>in my case, i don't get the correct values of dual variables.</div><div>The earlier example is one iteration of column generation, at these step</div><div>scip found the optimal solution of the master problem, so no need to generate new columns,</div><div>the problem is that the value of dual variable are all zero, which is not correct, and scip</div><div>continue to generate new columns.</div></div><div><br></div><div>So how we can get dual variables in pricing if scip don't provide dual information ? </div><div><br></div><div>Best regards</div><div><br></div><div>A. Ouali </div><div><br></div><div> <br><br><div><hr id="stopSpelling">Date: Thu, 16 Oct 2014 18:17:20 -0300<br>Subject: Re: [Scip] Getting duals values of best solution<br>From: rodolfo.carvajal@gmail.com<br>To: oualiaek@hotmail.fr<br><br><p dir="ltr">Hi Abdelkader,<br>
If you solve your MIP as a SCIP problem, you don't get dual information (see the SCIP FAQ <a href="http://scip.zib.de/#faq" target="_blank">http://scip.zib.de/#faq</a>).<br>
You can use the LP interface (lpi/lpi.h) to interact with the LP solver and get the duals.</p>
<p dir="ltr">Hope this helps,<br>
Rodolfo</p>
<div class="ecxgmail_quote">On Oct 16, 2014 5:49 PM, "Abdelkader Ouali" <<a href="mailto:oualiaek@hotmail.fr">oualiaek@hotmail.fr</a>> wrote:<br><blockquote class="ecxgmail_quote" style="border-left:1px #ccc solid;padding-left:1ex;">
<div><div dir="ltr">Dear scip users,<div><br><div><div>I have a short example of ILP, and i want to know how to get dual values of optimal solution,</div><div>when i use cplex, it give me the correct value of dual variables,</div><div>but when using scip the dual values is all zero, knowing that i set the pointers of constraint to the transformed</div><div>ones, in attachment you will find source code containing the example and how i do to get the dual values.</div><div><br></div><div>I want to know what is wrong in this code ?</div></div><div><br></div><div>Best regards</div><div><br></div><div>A. Ouali </div></div> </div></div>
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