petsc-3.12.5 2020-03-29

PetscSFCompose

Compose a new PetscSF by putting the second SF under the first one in a top (roots) down (leaves) view

#include "petscsf.h" 
PetscErrorCode PetscSFCompose(PetscSF sfA,PetscSF sfB,PetscSF *sfBA)

	sfA	- The first PetscSF, whose local space may be a permutation, but can not be sparse.
	sfB	- The second PetscSF, whose number of roots must be equal to number of leaves of sfA on each processor

sfBA -The composite SF. Doing a Bcast on the new SF is equvalent to doing Bcast on sfA, then Bcast on sfB

For the resulting composed SF to be valid, the input SFs must be true star forests: the leaves must be unique. This is checked in debug mode.

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