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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Hi John,<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>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>thanks for your prompt reply. Unfortunately it doesn't work no
matter what parameters I pass. I have also updated to the most recent TRUNK to
make sure I'm not finding old bugs. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Still, the duals don't get updated and the result is infeasible.
<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>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Regards<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Sebastian<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>
<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"'> John J Forrest
[mailto:jjforre@us.ibm.com] <br>
<b>Sent:</b> Dienstag, 21. Juli 2009 16:14<br>
<b>To:</b> Sebastian Theophil<br>
<b>Cc:</b> clp@list.coin-or.org; clp-bounces@list.coin-or.org<br>
<b>Subject:</b> Re: [Clp] Problem infeasible after fast dual although only
bound changed?<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p style='margin-bottom:12.0pt'>Sebastian,<br>
<br>
If you want the duals updated then it should be startFastDual(2) - see
OsiClpSolverInterface.hpp;<br>
<br>
John Forrest<br>
<br>
<img width=16 height=16 id="_x0000_i1025"
src="cid:image001.gif@01CA0A1F.E14686C0"
alt="Inactive hide details for "Sebastian Theophil" ---07/21/2009 07:33:45 AM---Hi, I have a very simple primal degenerate LP proble"><span
style='color:#424282'>"Sebastian Theophil" ---07/21/2009 07:33:45
AM---Hi, I have a very simple primal degenerate LP problem:</span><o:p></o:p></p>
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src="cid:image003.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt;color:#5F5F5F'>From:</span><o:p></o:p></p>
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<p class=MsoNormal><img width=1 height=1 id="_x0000_i1027"
src="cid:image004.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt'>"Sebastian Theophil"
<stheophil@think-cell.com></span><o:p></o:p></p>
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src="cid:image003.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt;color:#5F5F5F'>To:</span><o:p></o:p></p>
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src="cid:image004.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt'><clp@list.coin-or.org></span><o:p></o:p></p>
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src="cid:image003.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt;color:#5F5F5F'>Date:</span><o:p></o:p></p>
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<span style='font-size:10.0pt'>07/21/2009 07:33 AM</span><o:p></o:p></p>
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<span style='font-size:10.0pt;color:#5F5F5F'>Subject:</span><o:p></o:p></p>
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src="cid:image004.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt'>[Clp] Problem infeasible after fast dual
although only bound changed?</span><o:p></o:p></p>
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src="cid:image003.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt;color:#5F5F5F'>Sent by:</span><o:p></o:p></p>
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<p class=MsoNormal><img width=1 height=1 id="_x0000_i1035"
src="cid:image004.png@01CA0A1F.E14686C0"><br>
<span style='font-size:10.0pt'>clp-bounces@list.coin-or.org</span><o:p></o:p></p>
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<br>
<br>
<tt><span style='font-size:10.0pt'>Hi,</span></tt><span style='font-size:10.0pt;
font-family:"Courier New"'><br>
<br>
<br>
<tt>I have a very simple primal degenerate LP problem:</tt><br>
<br>
<tt>\Problem name: </tt><br>
<br>
<tt>Minimize</tt><br>
<tt>obj: x2</tt><br>
<tt>Subject To</tt><br>
<tt>cons0: x0 + x2 >= -0</tt><br>
<tt>cons1: - x0 + x2 >= -10</tt><br>
<tt>cons2: x1 + x2 >= -0</tt><br>
<tt>cons3: - x1 + x2 >= -10</tt><br>
<tt>Bounds</tt><br>
<tt>x0 Free</tt><br>
<tt>x1 Free</tt><br>
<tt>x2 Free</tt><br>
<tt>End</tt><br>
<br>
<tt>The primal solution is (5, 5, -5), but there are two dual solutions</tt><br>
<tt>(0.5, 0.5, 0, 0) and (0, 0, 0.5, 0.5). </tt><br>
<tt>The code below reads the file, searches a dual positive variable and</tt><br>
<tt>changes the RHS of the associated constraint. The constraint can no</tt><br>
<tt>longer be binding, and the dual solution should change solution after
a</tt><br>
<tt>resolve. This works as expected without startFastDual. </tt><br>
<br>
<tt>If startFastDual is active, the dual solution doesn't change though</tt><br>
<tt>although it is no longer feasible. </tt><br>
<br>
<tt>OsiClpSolverInterface solver;</tt><br>
<tt>solver.readLp("C:\\primaldegenerate1.lp");</tt><br>
<tt>solver.initialSolve();</tt><br>
<br>
<tt>solver.startFastDual(0);</tt><br>
<br>
<tt>int nRow=0;</tt><br>
<tt>for(; nRow<solver.getNumRows(); ++nRow) {</tt><br>
<br>
<tt>if(abs(solver.getRowPrice()[nRow])>gvEPSILON_CONSTRAINT) {</tt><br>
<tt>break;</tt><br>
<tt>}</tt><br>
<tt>}</tt><br>
<br>
<tt>solver.setRowLower( nRow, solver.getRowLower()[nRow]-1.0</tt><br>
<tt>);</tt><br>
<tt>solver.resolve();</tt><br>
<tt>solver.stopFastDual();</tt><br>
<br>
<br>
<tt>Is this a bug or am I doing sth wrong? I thought bound changes inside</tt><br>
<tt>fast dual were allowed. What would be the fastest way to resolve the</tt><br>
<tt>system after such a change? </tt><br>
<br>
<br>
<tt>Thanks,</tt><br>
<tt>Sebastian</tt><br>
<br>
<tt>--</tt><br>
<tt>Sebastian Theophil . stheophil@think-cell.com</tt><br>
<tt>Software Engineer</tt><br>
<br>
<tt>think-cell Software GmbH . Invalidenstr. 34 . 10115 Berlin, Germany </tt><br>
<tt><a href="http://www.think-cell.com">http://www.think-cell.com</a> .
phone +49-30-666473-10 . toll-free (US) +1-800-891-8091</tt><br>
<tt>Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl . Amtsgericht
Berlin-Charlottenburg, HRB 85229</tt><br>
<br>
<br>
<tt>_______________________________________________</tt><br>
<tt>Clp mailing list</tt><br>
<tt>Clp@list.coin-or.org</tt><br>
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<br>
</span><o:p></o:p></p>
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<!--[object_id=#0342cca8cd3ef743bdaeaa37dbcc7c82#]--><P style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma,Verdana,Arial">--<BR>Sebastian Theophil (<A href="mailto:stheophil@think-cell.com">stheophil@think-cell.com</A>)<BR>Software Engineer </P><!--[object_id=#think-cell.com#]--><TABLE style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma,Verdana,Arial" cellSpacing=0>
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<TD style="PADDING-RIGHT: 10pt">think-cell Software GmbH</TD>
<TD colSpan=2><A href="http://www.think-cell.com/">http://www.think-cell.com</A></TD></TR>
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<TD style="PADDING-RIGHT: 10pt">Invalidenstr. 34</TD>
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<TD colSpan=3>Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl</TD></TR>
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