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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hello,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am working with IpOpt to solve an optimization problem with non-linear constraints. Most of the time it converges to the solution without any problem, but there is a certain set of similar cases where I keep getting the “infeasible problem detected” error. Having checked the constraints, it seems that there is always a violation of at least 1e-3, and IpOpt cannot get past it despite it being practically at what I know to be the solution already. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have tried lowering the tolerance to allow that margin of error but I get a restoration phase failure with the message: “Restoration phase converged to a feasible point that is unacceptable to the filter for the original problem”, and the scaled dual infeasibility is always at 100. Also, since those cases happen when one particular variable is at 0, I have tried putting the problematic constraints as respected in those cases, but then IpOpt can’t get to the solution at all because of discontinuity issues I suspect.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am a bit stomped by this situation and any help or suggestion would be well appreciated. Has anyone faced this kind of situation before? Is there a workable way to make IpOpt ignore certain constraints in certain conditions, or should I try something else completely?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thank you,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Maxime<o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-CA'>------ <br>IMPORTANT LEGAL NOTICE: This e-mail and any files transmitted with it are the property of FLOGEN Organization and/or its affiliates, are confidential, and are intended solely for the use of the individual or entity to whom this e-mail is addressed. If you are not a named recipient or otherwise have reason to believe that you have received this message in error, please notify the sender and delete this message immediately from your computer. Any other use, retention, dissemination forwarding, printing or copying of this e-mail is strictly prohibited. This e-mail is for information purposes only and does NOT constitute any binding acceptance of any offer, deal, contract, settlement of any sort by FLOGEN, its directors, managers or employees. You are hereby notified that FLOGEN does not do any acceptance orally, by e-mail or any other informal way but only through legally signed written agreements. Although this email and any attachments are believed to be free of any virus or other defect that might affect any computer system into which it is received, and opened, it is the responsibility of the recipient to ensure that it is virus free and no responsibility is accepted by FLOGEN Organization and/or its affiliates for any loss or damage arising in any way from its use.</span><span style='mso-fareast-language:EN-CA'><o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>