Rethink nullspace tutorials
Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 30/100
- Issue type
- Documentation
- Clarity
- Needs clarification
- Activity status
- Stale
- Tech stack
- jupyter-notebook
- Domain
- documentation
Research direction
Start by reviewing the nullspace material in the tutorial and compare it with the linked Firedrake elasticity notebook and MFEM hypre source. Check the direct-solver and iterative-solver option cases described in the issue, then define the tutorial changes needed for separate constant-nullspace and elasticity guidance, including the solver choice discussion.
Written by the indexing model from the issue text.
Description
Direct solver
PETSc does magic after the fact with nullspace information, which is "correct", but mumps might fail if
icntl_24:1 and inctl_25: 0 is not set for more complex spaces.
Iterative solver
Hypre/Boomeramg ignores the near nullspace if
"pc_hypre_boomeramg_nodal_coarsen": (1-6)
"pc_hypre_boomeramg_vec_interp_variant": (1-3)
is not set.
Thus currently has no effect.
Should consider a two stage approach, stating that constant nullspace is "trivial", and make another one for elasticity,
following guidelines form either:
https://colab.research.google.com/github/firedrakeproject/notebooks/blob/main/03-elasticity.ipynb
or
https://docs.mfem.org/4.8/hypre_8cpp_source.html#l05296
for option tests.
Since the problems are symmetric, Im not sure why I chose gmres and not cg ...
Discussed with @MariusCausemann
- Dominant language
- Jupyter Notebook
- Stars
- 167
- Forks
- 89
- Avg merge
- 3h 25m
- Merged PRs (30d)
- 2
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