Continuation of Equilibria / Formulation of Autonomous System

Just to make your question clearer: a MX error is raised at STEP -1, indeed. Furthermore, there is a Warning: Matrix is singular to working precision.

Hi Jonathan.

Interesting question. It is true that the 'ep' toolbox only handles autonomous vector fields. Making a non-autonomous vector field autonomous through the introduction of a phase variable, however, violates the condition for an equilibrium, since the rate of change of the phase variable is nonzero. This is the reason for a failure to converge, since there is no solution to converge to. The 'ep' toolbox simply isn't designed for this case.

My recommendation is to use calls to coco_add_funcand coco_add_pars to define a zero problem and appropriate monitor functions that imposes vanishing rates of change of the position and velocity variables, but not the phase variable. You will not get the bells and whistles of the 'ep' toolbox, e.g., bifurcation detection, but then again these don't apply to your non-autonomous problem anyway.

I hope that helps.

Harry

Hi Harry,

thank you, I think I'm understanding the theory behind your answer.

Jonathan