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Pass a null space through a nonlinear solver

+1 vote

Hi all,
I'm trying to solve a nonlinear elasticity problem, and want to eliminate the rigid body modes. With a linear solver, I use solver.set_nullspace, but I don't see a way to pass it to a nonlinear solver (which would then pass it to the associated linear solver). Seems that I will have to make my own NL solver to be able to use it, or find a way to pass it directly to snes.

Did I miss an option or something? If not, I will create a dolfin issue about this.

Thanks

asked Jul 31, 2014 by mwelland FEniCS User (8,410 points)

1 Answer

+1 vote
 
Best answer

You did not miss anything. To do more low-level things one must go from NonlinearVariationalSolver to NewtonSolver. Check cahn-hilliard demo.

answered Aug 5, 2014 by Jan Blechta FEniCS Expert (51,420 points)
selected Aug 5, 2014 by mwelland

Thanks Jan, so I think I would have to create the linear solver (set the nullspace) and then pass it to the newton solver through the constructor. Is that correct?

commented Aug 5, 2014 by mwelland FEniCS User (8,410 points)

This should work.

commented Aug 5, 2014 by Jan Blechta FEniCS Expert (51,420 points)
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