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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">I tried primal, dual and barrier using CLP standalone, all give the same result ~ close enough. 79596.39 79596.40 and 79596.29…<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> clp-bounces@list.coin-or.org [mailto:clp-bounces@list.coin-or.org]
<b>On Behalf Of </b>Jonathan Currie<br>
<b>Sent:</b> Sunday, May 27, 2012 6:18 PM<br>
<b>To:</b> 'Akhil langer'; 'clp@list.coin-or.org'<br>
<b>Subject:</b> Re: [Clp] different optimal values with primal and dual methods.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">Hi Akhil,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">I'm not sufficiently experienced to be able to answer why the solvers give such different answers (I assume there are multiple factors), however
note I ran your model using the OPTI Toolbox across the LP solvers I have and found CLP did not return the minimum (using the default settings) for either the dual or primal solvers:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">Test Problem [LP] Result<o:p></o:p></span></p>
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color:#1F497D">--------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"> Solver Status Fval Time<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"> cplex OK +79596.2542 0.7609s<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"> mosek FAIL +79596.2164 1.0940s<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">clp (dual) OK +114009.8970 0.3482s<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">clp (primal) OK +79605.5292 0.7370s<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"> glpk FAIL +0.0000 1.9977s<o:p></o:p></span></p>
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color:#1F497D"> qsopt OK +79596.2542 0.8384s<o:p></o:p></span></p>
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color:#1F497D"> matlab OK +79596.2542 7.7259s<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">--------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">I assume you obtained the same minimums as above using CLP? How was the original model created?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">Jonathan Currie<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ" style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> clp-bounces@list.coin-or.org [mailto:clp-bounces@list.coin-or.org]
<b>On Behalf Of </b>Akhil langer<br>
<b>Sent:</b> Sunday, 27 May 2012 2:17 p.m.<br>
<b>To:</b> clp@list.coin-or.org<br>
<b>Subject:</b> [Clp] different optimal values with primal and dual methods.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-NZ">I am attaching a linear program model file in mps format. I am trying to solve it using the driver.cpp program in the examples directory of the coin-clp distribution. Surprisingly, I am getting different optimal values
when solved using the dual and primal methods (model.dual(), model.primal()). Can someone please look into it and help me resolve this issue.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-NZ"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-NZ">Some help as early as possible will be useful as I am in a critical phase of my project.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-NZ"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-NZ">Thanks,<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-NZ">Akhil<o:p></o:p></span></p>
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