[Ipopt] Problems in models in C++

Dan yanndan at yahoo.com
Wed Feb 9 04:57:18 EST 2011

Dear all,
I have a problem with the C++ Interface. I am currently coding some network models. I tried to model a small instance like the hs_071 example and it went well.
I coded my network in term of functions that my TNLP class will called if needed.  When I run it, it does not find a solution and it goes into a loop.I caught this message run by IPOPT:"WARNING : Problem in step computation; switching to emergency code."
In order to solve my problem, I tried several thing including the derivative checker and two weird things appears:my jacobian is not dense. I can not figure why. I checked at almost step and I can not find why the derivative checker of my jacobian is dense.the value found by the derivative checker are eccentric. It says mine are wrong while they are not. It is a adjacency matrix so it is only 1 and -1.If you have any ideas to solve my problem of ways to find my errors, I would greatly appreciate.
Best Regards,Dan

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