DOLFIN

How to get assembled matricies from NonlinearVariationalSolver?

Asked by minak

Hello Everyone,

I am solving nonlinear system of PDEs and everything works fine
problem = NonlinearVariationalProblem(F, w, bcs=bcs, J=J, form_compiler_parameters=ffc_options)
solver = NonlinearVariationalSolver(problem)

The problem is that I would like look at the assembled matrices. The only solution I found already is to set parameters
solver.parameters["print_rhs"] = True
solver.parameters['print_matrix'] = True

Then we obtain <Matrix wrapper of <uBLASMatrix of size ... x ...> to std output, but this is not very convenient.

How can I assign this matrix to the variable (in particular in each Newton iteration) it will allow me to make some operations on the matrix.

Thank you,
minak

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Jan Blechta (blechta) said : 		#1

You can do this sort of things by subclassing NonlinearProblem and overloading its F(), J() or form() method like in Cahn-Hilliard demo. I think more comprehensive examples of this sort of things is in another demo..

Jan

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