How to get the matrix of linear operator?

Question

Hi!
I have a solution u and functional f:

V = FunctionSpace(mesh, 'Lagrange', 1)
u = Function(V)
...
n = FacetNormal(mesh)
h_edges = FacetArea(mesh)
f = (sqrt(h_edges("+"))*jump(grad(u),n))**2*dS

How can I get a matrix of operator
A:V->V,
Au = sqrt(h_edges)*jump(grad(u),n)

Thanks!

Comments

Hi, is $A(u+v) = Au + Av$ ?

---

Sorry, of course, I have corrected.
I want for any given solution u:
v = Function(V)
v.vector() = Au.vector()
f(u) == assemble(v**2*dS)

Answer 1

Not sure if I really understand the question. Anyway, in
nonlinear elasticity problems it is common to seek
the minimiser of an energy functional. The way this
is done is to define the nonlinear energy functional
which is the differentiated twice to get the matrix and
right hand side to be solved
in each iteration in a Newton algorithm. Look
for example in the hyperelasticity demo for an
example of how this is done.