Hi Michel,
I have a problem with your commit b58eaa8e2b869f894b480c371ba60e14cf6ede7e where you added (two years ago) a test for 0/0 generalized eigenvalues. If I remember correctly, in this case any complex number is a generalized eigenvalue so the model has no unique solution. If the numerator and the denominator are less that 1e-6, then mjdgges issues an error message with info equal to -30. My problem is related to the hard coded threshold.
In this RBC model:
https://gist.github.com/stepan-a/5757263
the technology is characterized by a Constant Elasticity of Substitution production function. If psi is less than -1, that is if the elasticity of substitution is less than one half, Dynare fails because of the condition introduced in your commit. The problem is that I am almost certain that the model admits a solution for smaller values of psi. It is well known that there exists a closed form solution for the (continuous time) Ramsey model with Harrod-Domar technology (psi->\infty). Also, I am able to simulate this model with the (stochastic) extended path approach for much smaller values of psi.
I know that with this model, because of the almost kinked production function, the perturbation solution in such case would most likely deliver a very crude approximation but it would be nice to have something (and not an error message).
Are you okay if I add an option for this threshold? Do you have a rational for the hard coded value? I will try to push a branch tomorrow...
Best, Stéphane.