[Ipopt] TOO_FEW_DOF error for overconstrained (but feasible) problem

[Etienne Vouga]

I am trying to solve a problem with 54 variables and 63 equality
constraints. Several of the constraints are redundant -- so the problem is
feasible -- but finding a minimal set is nontrivial and changes depending
on the configuration.

When I try to solve the problem, Ipopt aborts with the error TOO_FEW_DOFS.
Writing the equality constraints as inequality constraints -epsilon < g(x)
< epsilon does allow ipopt to run and converge.

Is there a better solution?
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