Can we define a constant as an unknown constant

Hello

I want to ask if we can define a constant to be unknown as to get its value from the solver. For example in this code pyadjoint/time-distributed-control.py at master · dolfin-adjoint/pyadjoint · GitHub can we define the nu as an unknown constant?

Thank you.

Do you want to solve a PDE for the constant?if so you should use the “Real” element.