PetscCommDuplicate

Duplicates the communicator only if it is not already a PETSc communicator.

Synopsis

#include "petscsys.h"   
PetscErrorCode PetscCommDuplicate(MPI_Comm comm_in, MPI_Comm *comm_out, PetscMPIInt *first_tag)

Collective

Input Parameter

• comm_in - Input communicator

Output Parameters

• comm_out - Output communicator. May be comm_in.

• first_tag - Tag available that has not already been used with this communicator (you may pass in NULL if you do not need a tag)

Note

PETSc communicators are just regular MPI communicators that keep track of which tags have been used to prevent tag conflict. If you pass a non-PETSc communicator into a PETSc creation routine it will attach a private communicator for use in the objects communications. The internal MPI_Comm is used to perform all the MPI calls for PETSc, the outer MPI_Comm is a user and is not used by PETSc.

See Also

PetscObjectGetNewTag(), PetscCommGetNewTag(), PetscCommDestroy()

Level

developer

Location

src/sys/objects/tagm.c

Examples

src/ksp/ksp/tutorials/ex73.c

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