PETSc version 3.16.6

MatMPIAdjCreateNonemptySubcommMat

create the same MPIAdj matrix on a subcommunicator containing only processes owning a positive number of rows

#include "petscmat.h" 
PetscErrorCode MatMPIAdjCreateNonemptySubcommMat(Mat A,Mat *B)

Collective

- original MPIAdj matrix

- matrix on subcommunicator, NULL on ranks that owned zero rows of A

This function is mostly useful for internal use by mesh partitioning packages that require that every process owns at least one row.

The matrix B should be destroyed with MatDestroy(). The arrays are not copied, so B should be destroyed before A is destroyed.

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