Callbacks on Newton solver

[klunkean]

I just wanted to add that, to me, it feels wrong to define res and Dres globally and then use those global variables in the CustomNonlinearProblem class.
Just for - in my opinion - cleaner code I would set the linear and bilinear forms as attributes supplied to the __init__ method as done here:

Set krylov linear solver paramters in newton solver

I recommend designing your own NewtonSolver and setting the options using PETSc. Here’s a quick example based on the nonlinear poisson demo. import matplotlib.pyplot as plt from dolfin import * class Problem(NonlinearProblem): def __init__(self, J, F, bcs): self.bilinear_form = J self.linear_form = F self.bcs = bcs NonlinearProblem.__init__(self) def F(self, b, x): assemble(self.linear_form, tensor=b) for bc in self.bcs: bc.…

For this kind of reply I would really like to have something like a comment function as known from stackoverflow…