Dear all,
I am trying to minimize a functional of the form
$$J(f) = \sum_i ||y_i - f(x_i)||^2 + Regularizer(f)$$
where Regularizer gives rise to a nonlinear problem. To convert this to a functional that can be minimized with Fenics, I rewrite it as in http://www.geometrictools.com/Documentation/ThinPlateSplines.pdf, equation (25). Unfortunately I haven't found a way to implement the Delta function that appears there in Fenics. The PointSource class doesn't work, because the magnitude there is constant, but I need something that depends on the function. Also I haven't figured out how to make PointSource work with the NonlinearVariationalSolver.
Do you have any suggestions as to how my objective can be implemented?
Best,
Philipp.
