You can see https://petsc.org/main/docs/manualpages/PC/PCASM.html It is very simple as you can see but you are limited to one block per MPI process. If you want more then you need to create them and use https://petsc.org/main/docs/manualpages/PC/PCASMSetLocalSubdomains.html#PCASMSetLocalSubdomains
Mark On Tue, Apr 12, 2022 at 4:14 AM markwinpe <markwi...@163.com> wrote: > Dear PETSc’s developers, > > Currently, I don’t have a geometric mesh for a PDE problem, I just > got a matrix from others and I want to use the ASM preconditioner to solve > the linear system. I would be appreciated if you could describe how PETSc > defines the overlap in the context of using the algebraic ASM > preconditioner. > > > > Best, > > > Wenpeng >
