Default parameters for NonLinearVariationalSolver

Linear Algebra
1

Hi all,

I’m looking for the default parameters of the NonLinearVariationalSolver.

I’m running

info(NonlinearVariationalSolver.default_parameters(), True)

And get a lot of “default” strings.

I’m mostly looking for the default linear solver and pre-conditioner.

Can anyone point me towards the relevant documentation?

Thanks in advance!

2

See, e.g., Bitbucket

See also Default absolute tolerance and relative tolerance - #2 by nate

1 Like
3

Thanks @nate unfortunately, as you can see here it still shows “default” for the linear solver.

4

Whoops. Yep. I just realised this after writing. If you dig around in the source you’ll likely find what you’re looking for.

If I remember rightly, old dolfin defaults to umfpack in serial and mumps in parallel, for the linear solve.

1 Like
5

This is what I read here and there yes. No preconditioners by default I suppose then since they don’t use a preconditioner, right?

6

If you want to do fancier things with preconditioning your system in conjunction with an iterative solver, I highly recommend migrating to DOLFINx. The Stokes demo is a great place to start.

Otherwise there are some old examples knocking around, e.g.,

https://bitbucket.org/fenics-project/dolfin/src/master/python/demo/undocumented/elasticity/demo_elasticity.py