Intergrating a user-designed linear solver

[rebpoli]

Hi all,

I have a linear solver I'd like to test in libmesh.
Can you provide some directions on how to integrate it?
What are the main hooks I should look at?
I am using linear and nonlinear implicit systems.

Thanks,
Renato

[jwpeterson]

I guess you are referring to implementing a "meta" solver that would combine some existing PETSc (or other) linear solvers in a new way, and not implementing your own linear solver from scratch? The LinearSolver class hierarchy in libmesh has specific implementations for PETSc, Eigen, and others, so I would probably start there.

[rebpoli]

It is a separate solver. I will take a look at LinearSolver, thanks.

[roystgnr]

Agreed with John that subclassing LinearSolver may be the best way to start for you. After you have things working for linear problems, you could try using your LinearSolver within a libMesh::NewtonSolver and attaching that to your NonlinearImplicitSystem, then giving your custom LinearSolver to it. That'll at least see how things perform with your linear solver wrapped in a quasi-Newton + line search outer solver. I'm not sure how best to connect a custom linear solver to the more sophisticated nonlinear solvers in PETSc SNES, though.

[rebpoli]

I will dig into that. I understand your point.
Thanks.