petsc-3.13.6 2020-09-29

DMCompositeGetGlobalISs

Gets the index sets for each composed object

#include "petscdmcomposite.h"  
PetscErrorCode  DMCompositeGetGlobalISs(DM dm,IS *is[])

Collective on dm

dm -the packer object

is -the array of index sets

The is entries should be destroyed with ISDestroy(), the is array should be freed with PetscFree()

These could be used to extract a subset of vector entries for a "multi-physics" preconditioner

Use DMCompositeGetLocalISs() for index sets in the packed local numbering, and DMCompositeGetISLocalToGlobalMappings() for to map local sub-DM (including ghost) indices to packed global indices.

The output argument 'is' must be an allocated array of sufficient length, which can be learned using DMCompositeGetNumberDM().

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