<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Hi Stefan,<div><br></div><div>Thanks again for your quick answers. Now it works with GAMS 23.3 or GAMS 23.4. </div><div><br></div><div>Maybe to help you to better understand where this problem comes from. My math problem contains a Kirchhoff's law about flows in my network. Now I would like to consider the same law for the energy of my network.( I was considering the energy in my network was the same everywhere.)</div><div><br></div><div>So i changed my equation of nodes from </div><div>\sum f_{i,j} = 0</div><div>to </div><div>\sum Energy{i,j}*f_{i,j} =0</div><div><br></div><div>That's how I get IPOPT causing sytem error. I did not change a thing in my non-differentiable equations.</div><div><br></div><div>Thanks agains Stefan, your help was highly useful.</div><div><br></div><div>Best Regards,</div><div>Dan</div><div><br></div><div>--- En
date de : <b>Jeu 27.5.10, Stefan Vigerske <i><stefan@math.hu-berlin.de></i></b> a écrit :<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>De: Stefan Vigerske <stefan@math.hu-berlin.de><br>Objet: Re: [Ipopt] Error system of Ipopt when using GAMS<br>À: "yanndan bronx" <yanndan@yahoo.com><br>Cc: "ipopt mailing list" <ipopt@list.coin-or.org><br>Date: Jeudi 27 mai 2010, 16h33<br><br><div class="plainMail">Hi,<br><br>thanks for the instance.<br>I can reproduce your problem.<br>With GAMS 23.4 I also get the message<br><br> Internal error 2 in QAMD : Schur size expected: 0 Real: 1<br> ** MPI_ABORT called<br><br>I believe this comes from Mumps, the linear solver that is used in Ipopt<br>(with GAMS 23.4, MUMPS 4.9 is used; with 23.3, it was 4.8).<br><br>And I guess that Mumps fails because of some invalid values in
the<br>Hessian. Ipopt computes the Hessian in the starting point.<br>Unfortunately, x|x| is not twice differentiable at x=0, and thus there<br>may be something going wrong (I have not debugged yet).<br>I tried setting the Ipopt option check_derivatives_for_naninf to yes,<br>but that did not result in complains.<br><br>Anyway, if you tell Ipopt not to use the GAMS hessian's, but to<br>approximate it, then it should work better. So try setting<br> hessian_approximation limited-memory<br>in your coinipopt.opt file.<br>Changing the starting point did not work for me, unfortunately.<br><br>Stefan<br><br>Am 27.05.2010 15:51, schrieb yanndan bronx:<br>> Hi Stefan,Thanks for your quick answer. I joining a file .gms which should reproduce the error. Sorry if the file is not commented but I am using several text files to create my model. I used CONVERT to extract the core of the problem.<br>> I am using f(x)= x|x| as non-differentiable
function.<br>> Thanks again for your help.<br>> Best Regards,Dan<br>> --- En date de : Jeu 27.5.10, Stefan Vigerske <<a ymailto="mailto:stefan@math.hu-berlin.de" href="/mc/compose?to=stefan@math.hu-berlin.de">stefan@math.hu-berlin.de</a>> a écrit :<br>> <br>> De: Stefan Vigerske <<a ymailto="mailto:stefan@math.hu-berlin.de" href="/mc/compose?to=stefan@math.hu-berlin.de">stefan@math.hu-berlin.de</a>><br>> Objet: Re: [Ipopt] Error system of Ipopt when using GAMS<br>> À: "yanndan bronx" <<a ymailto="mailto:yanndan@yahoo.com" href="/mc/compose?to=yanndan@yahoo.com">yanndan@yahoo.com</a>><br>> Cc: <a ymailto="mailto:ipopt@list.coin-or.org" href="/mc/compose?to=ipopt@list.coin-or.org">ipopt@list.coin-or.org</a><br>> Date: Jeudi 27 mai 2010, 12h16<br>> <br>> Hi,<br>> <br>> can you send the model so one can try to reproduce?<br>> You seem to use model type DNLP? What non-differentiable functions
are<br>> you using?<br>> You mal also wanna try GAMS 23.4.<br>> <br>> Stefan<br>> <br>> Am 27.05.2010 11:50, schrieb yanndan bronx:<br>>> Hello Everyone,<br>>> I have a weird problem with IPOPT using GAMS Interface. My problem is an non linear problem. I tried to resolve it on real instances but I got errors of the system. So I reduced my instances to a problem of small size which can be solved with a pen and a paper.However I still have an error system. I reproduce at the end of this message the solution report :<br>>> I try to solve it with COUENNE and I get my solution. I tried with BONMIN ( I cheated, I toldBONMIN that my problem was MINLP) BONMIN called Ipopt and we get the same error sytem.<br>>> I am a bit stubborn, so I would like to see if the problem was coming from GAMS. I used CONVERT to transpose my instance into AMPL format. I tried and IPOPT achieve maximum of
iterations. BONMIN and COUENNE find quickly the solution of my problem.<br>>> Have you got any ideas to solve this kind of problem.<br>>> Best Regards, Dan<br>>><br>>><br>>><br>>> ********************************************************************************************************************************************************************************************************************MODEL STATISTICS<br>>> BLOCKS OF EQUATIONS 3 SINGLE EQUATIONS 12BLOCKS OF VARIABLES 5 SINGLE VARIABLES 41 6 projectedNON ZERO ELEMENTS 78 NON LINEAR N-Z 69DERIVATIVE POOL
16 CONSTANT POOL 19CODE LENGTH 377<br>>><br>>> GENERATION TIME = 0.125 SECONDS 4 Mb WIN233-233 Dec 15, 2009<br>>><br>>> EXECUTION TIME = 0.219 SECONDS 4 Mb WIN233-233 Dec 15, 2009GAMS Rev 233 WIN-VIS 23.3.3 x86/MS Windows 05/27/10 09:13:46 Page 7G e n e r a l A l g e b r a i c M o d e l i n g S y s t e mSolution Report SOLVE min_Master_1 Using DNLP From line 406<br>>><br>>> S O L V E
S U M M A R Y<br>>> MODEL min_Master_1 OBJECTIVE f_obj TYPE DNLP DIRECTION MINIMIZE SOLVER COINIPOPT FROM LINE 406<br>>> **** SOLVER STATUS 13 System Failure **** MODEL STATUS 13 Error No Solution **** OBJECTIVE VALUE NA<br>>> RESOURCE USAGE, LIMIT NA 1000.000 ITERATION COUNT, LIMIT NA 2000000000 EVALUATION ERRORS
NA 0<br>>> GAMS/CoinIpopt NLP Solver (IPOPT Library 3.7)written by A. Waechter<br>>> List of user-set options:<br>>> Name Value used max_cpu_time = 300 yes<br>>> ******************************************************************************This program contains Ipopt, a library for large-scale nonlinear optimization. Ipopt is released as open source code under the Common Public License (CPL). For more information visit <a
href="http://projects.coin-or.org/Ipopt******************************************************************************" target="_blank">http://projects.coin-or.org/Ipopt******************************************************************************</a><br>>> NOTE: You are using Ipopt by default with the MUMPS linear solver. Other linear solvers might be more efficient (see Ipopt documentation).<br>>><br>>> Exception of type: IpoptException in file "Unknown File" at line -1: Exception message: Unknown Exception caught in Ipopt<br>>> No solution returned********************************************************************************************************************************************************************************************************************<br>>><br>>><br>>><br>>> <br>>><br>>><br>>><br>>>
_______________________________________________<br>>> Ipopt mailing list<br>>> <a ymailto="mailto:Ipopt@list.coin-or.org" href="/mc/compose?to=Ipopt@list.coin-or.org">Ipopt@list.coin-or.org</a><br>>> <a href="http://list.coin-or.org/mailman/listinfo/ipopt" target="_blank">http://list.coin-or.org/mailman/listinfo/ipopt</a><br>> <br>> <br>> <br>> <br>> <br><br></div></blockquote></div></td></tr></table><br>