[Ipopt] wrong "infeasibility" message

[Juan Carlos Lopez Alfonso]

Hi all,

I have written two days ago to this list and I have not received any
answer until this moment, sorry but I need suggestions and comments. I
need some help with my problem, because I have included a volumetric
constraint, which guarantee the existence and uniqueness of an optimal
solution, but in some cases the optimization algorithm ends with this
message: "EXIT: Converged to a point of local infeasibility. Problem
may be infeasible". I have made some test, and when I change the
initial point in the same problem, in some case the optimal solution
is reached and in others not. For example, I have computed the optimal
solution of my problem without this volumetric constraint, and after,
I have used this optimal solution as the initial point of the same
problem when I impose the volumetric constraint not so restrictive.
Therefore, I have used always the optimal solution of the last problem
to change the volumetric constraint more and more restrictive. With
this procedure, is possible to obtain the optimal solution of my
problem with a volumetric constraint more and more restrictive.

I cant use this procedure in my real problem, because is a big one, so
I can not compute a lot of optimal solutions in order to obtain the
optimal solution of my problem with my volumetric constraint.

Could any one give me suggestions or comments? Is there any way to
change the way to compute the step in each iteration in IPOPT? Please,
any comment will be really useful for my.

Thank you in advance and waiting for comments
Juan Carlos