Multiphase problem fails with IPOPT

[javigartieda]

Hello,

First of all, thank you for making DMG available. I'm currently using it to solve an optimal control problem with the Gauss Pseudospectral Method (GPM). I have been able to successfully implement a single-phase problem using IPOPT as the solver. However, when I attempt to solve a multiphase problem, the solver fails to converge, and I encounter issues with the code.

Here are some details:

The same problem runs fine with SNOPT, but fails with IPOPT.
It seems the issue is specific to how the IPOPT solver handles multiphase problems.
I've checked the documentation, but I couldn't find specific instructions or troubleshooting tips for multiphase configurations using IPOPT.
Could you provide any guidance or suggest modifications that would allow IPOPT to handle multiphase problems in the same way it does with SNOPT?

Thanks for your help and for this great contribution!