Hi Henrik, You can pass an alternative Jacobian (ie not the true derivative(J, u) ) to the solver by explicitly passing a form for J. The critical person who is the expert on this is Lawrence, who is away for the next week. I'm not sure if he's on email. Regards, David On Fri, 9 Oct 2015 at 14:16 Buesing, Henrik <HBuesing@eonerc.rwth-aachen.de> wrote:

Dear Firedrakers,

if I wanted to modify the diagonal entries of my Jacobian in a Newton step during a time step… How would I do this? Do I have to define my own preconditioner here?

Henrik

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Dipl.-Math. Henrik Büsing

Institute for Applied Geophysics and Geothermal Energy

E.ON Energy Research Center

RWTH Aachen University

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