I am trying to solve a set of PDEs and ODEs together as a mixed system. The ODE variables only depend on time, so I define them as functions from the real function space R.

First question: Is this a correct approach?

Second question: I am running into a “Mismatching function spaces” error; can someone please take a look at my code (found here) and let me know what I’m doing wrong? The error arises when the value of one of the mixed-system variables is assigned to another variable which belongs to the same function space. [I remember having the same issue some time ago, but I thought that it was fixed.]

Thank you.

Best, Anna.