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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Filip,<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'>Thank you for your help. Is it possible that using a different linear solver may help to avoid those local points of infeasibility on top of having a good initial guess?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I am presently using mumps.<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'>Maxime<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><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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"'> Filip Jorissen [mailto:filip.jorissen@kuleuven.be] <br><b>Sent:</b> Friday, April 06, 2018 3:13 AM<br><b>To:</b> Maxime Boulay<br><b>Cc:</b> Ipopt@list.coin-or.org<br><b>Subject:</b> Re: [Ipopt] Infeasible Problem Detected when the problem is actually feasible<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>It sounds like IPOPT converges to a local point of infeasibility? I.e. your equations are non-convex and you need a good/feasible initial guess to be able to converge to a feasible (local) optimum.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Filip<o:p></o:p></p><div><p class=MsoNormal><br><br><o:p></o:p></p><div><p class=MsoNormal>Op 5 apr. 2018, om 17:27 heeft Maxime Boulay <<a href="mailto:mboulay@flogen.com">mboulay@flogen.com</a>> het volgende geschreven:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Hello,<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>I am using IpOpt to solve a problem with about 20 variables and 20 constraints. I know the solution to this problem, and I have verified that my constraints are respected at the solution, there is also no error in the Derivative Checker. However, IpOpt still ends up giving me the Infeasible Problem Detected message when I run it. If I keep running it again with the "warm_start_init_point", it eventually does find the solution. This happens for many different entry values to this problem. Can anyone help me find a clue as to why this would happen?<span class=apple-converted-space> </span><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Thank you.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Maxime<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif"'>_______________________________________________<br>Ipopt mailing list<br></span><a href="mailto:Ipopt@list.coin-or.org"><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif";color:purple'>Ipopt@list.coin-or.org</span></a><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif"'><br></span><a href="https://list.coin-or.org/mailman/listinfo/ipopt"><span style='font-size:9.0pt;font-family:"Helvetica","sans-serif";color:purple'>https://list.coin-or.org/mailman/listinfo/ipopt</span></a><o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>