Hello All,

I was trying to provide a preconditioning form for my Newton solver. I wrote my own NewtonSolver and NonlinearProblem. Here’s what I observed:

- MyNewtonSolver.solver_setup (is exactly the same as NewtonSolver.solver_setup, just for test purpose) does be called and Preconditioning matrix does be created
- MyNonlinearProblem.J_pc(P, x) is never called.

MyNonlinearProblem.J_pc(P, x) is:

```
def J_pc(self, P, x):
print('jpc is called')
if self.j_pc is not None:
dolfin.assemble(self.j_pc, tensor=P)
for bc in self.bcs:
bc.apply(P)
```

Can anyone tell me what to do pls?

Thanks in advance,

Victor