[Ipopt-tickets] [Ipopt] #288: Cannot pass information through input variables

[Ipopt]

#288: Cannot pass information through input variables
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Reporter:  kamilova                      |      Owner:  ipopt-team
    Type:  defect                        |     Status:  new
Priority:  high                          |  Component:  Ipopt
 Version:  3.12                          |   Severity:  normal
Keywords:  input exception -101 Fortran  |
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 I am using IPOPT with Fortran for my NLP. Essentially I already had
 another optimisation routine working, and now I wanted to use Ipopt to
 compare. This required me to rewrite my functions a bit. I can create the
 problem handle with IPROBLEM. However, when I run it, I get an "Unknown
 exception caught in Ipopt" and error -101. According to the documentation,
 this means that there is a problem with my model. Since my model worked
 fine for the other optimisation method, I suspect it has to do with my
 coding skills.

 As far as I can tell, the problem is that for some bizarre reason, my
 input parameter "x" does not have any values in any of the subroutines
 (gradient, constraints, gradient of constraints, objective function,
 hessian...) used for IPOPT.

 I have printed all the other input parameters, such as number of
 optimisation variables, number of constraints, the dat and idat user
 defined values, etc... and they work fine. The problem is that x just
 doesn't have any value, and if I try to access it (printing, or accessing
 individual elements x(i) ) it returns the error. I have successfully
 printed x right before calling IPSOLVE and right after. But something
 happens during IPSOLVE that makes it not recognise my x.

 Any help would be greatly appreciated! I am very stuck!

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Ticket URL: <https://projects.coin-or.org/Ipopt/ticket/288>
Ipopt <http://projects.coin-or.org/Ipopt>
Interior-point optimizer for nonlinear programs.