doc/manual/ksp.md

964 index sets that define the subdomains.
994 overlap to compute in constructing the subdomains.
1004 explicitly set the subdomains in an application code, then all overlap
1013 the user to specify subdomains that span multiple MPI processes. This can be
1014 useful for problems where small subdomains result in poor convergence.
1018 a multigrid solver on the subdomains.
1028 subdomains that span multiple MPI processes. The simplest way to do this is
1030 the total number of subdomains `N` that is smaller than the MPI
1032 consecutive single-rank subdomains into a single multi-rank subdomain.
1033 The single-rank subdomains contain the degrees of freedom corresponding
1035 these are the subdomains `PCASM` and `PCGASM` use by default.
1042 partitioner that generates well-connected coarse subdomains first before
1043 subpartitioning them into the single-rank subdomains.
1046 subdomains by calling `PCGASMSetSubdomains(PC,IS[],IS[])` where each
1051 constructing multi-rank subdomains that can be then used with
1053 subdomains is by using the underlying `DM` object, if it is capable of
1061 subdomains via `PCGASMSetOverlap()` – this functionality works only
1062 for subdomains that fit within a single MPI process, exactly as in
1069 subdomains. The `runex62_2D_*` examples illustrate the use of
1161   >   the subdomains. This option automatically switches the smoother on the levels to be `PCASM`.
1508 condensation of the residual at the interior of the subdomains by means
1516 assumes a one-to-one mapping between subdomains and MPI processes.
1545 between subdomains. `PCBDDC` uses by default vertex continuities and
1590 When solving problems decomposed in thousands of subdomains or more, the
1599 the number of subdomains that will be generated at the next level; the
1600 larger the coarsening ratio, the lower the number of coarser subdomains.