[petsc-dev] Is the ASM preconditioner algebraic or geometric in the context of DMPlex (unstructured) ?

Matthew Knepley knepley at gmail.com
Sun May 8 08:21:52 CDT 2022

On Sun, May 8, 2022 at 12:44 AM markwinpe <markwinpe at 163.com> wrote:

> Dear PETSc’s developers,
>       In the context of unstructured applications developed by PETSc’s
> DMPlex, if the ASM is used for preconditioning, is it algebraic (based on
> matrix graph) or geometric (based on Metis partition)?
The ASM overlap is algebraic. You could use GASM and
DMPlexDistibuteOverlap() to get an overlap based on topology, but we have
not done this since
we are usually interested in the algebraic version.



>     When the ASM preconditioner is associated with a specific DM object, I
> found there is  only the implementation of DMCreateDomainDecomposition
> <https://www.petsc.org/release/src/dm/impls/da/dadd.c.html#DMCreateDomainDecomposition_DA> for
> DA in PCSetUp_ASM, and there is no implementation for DMPlex. So I guess
> the ASM is algebraic for DMPlex, is that right ?
> Best,
> Wenpeng

What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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