Vector Function

Question

I'd like to set up a problem of the form $\min \int |g(\nabla u) \nabla u- W|^2$ subject to boundary conditions on $u$. I haven vector field, $W$, currently set up as a standard vector valued python function. My question is really how do I "subtract" vector fields within fenics?

Answer 1

If your question is how to access different dimensions of a vector field you can use the sub() function. As an example if you have:

u = VectorFunctionSpace(..)

as your function space, you can access u in the X direction using u.sub(0), and u.sub(1) for the Y direction.