Intercommunicator Accessors

intercommunicator, accessors  

 MPI_COMM_TEST_INNER(comm, flag)

   IN     comm             communicator
   OUT    flag             true if comm is intercommunicator

MPI_COMM_TEST_INTER(COMM, FLAG, IERROR)INTEGER COMM, IERROR
LOGICAL FLAG

MPI_COMM_TEST_INTER is a local routine that allows the calling process to determine if a communicator is an intercommunicator or an intracommunicator. It returns true if it is an intercommunicator, otherwise false.

When an intercommunicator is used as an input argument to the communicator accessors described in Section , the following table describes the behavior.

Furthermore, the operation MPI_COMM_COMPARE is valid for intercommunicators. Both communicators must be either intra- or intercommunicators, or else MPI_UNEQUAL results. Both corresponding MPI_UNEQUAL local and remote groups must compare correctly to get the results MPI_CONGRUENT and MPI_SIMILAR. In particular, it is MPI_CONGRUENT MPI_SIMILAR possible for MPI_SIMILAR to result because either the local or remote groups were similar but not identical.

The following accessors provide consistent access to the remote group of an intercommunicator; they are all local operations.

 MPI_COMM_REMOTE_SIZE(comm, size)

   IN     comm         intercommunicator
   OUT    size         number of process in the remote
                       group of comm

MPI_COMM_REMOTE_SIZE(COMM, SIZE, IERROR)INTEGER COMM, SIZE, IERROR

MPI_COMM_REMOTE_SIZE returns the size of the remote group in the intercommunicator. Note that the size of the local group is given by MPI_COMM_SIZE.

 MPI_COMM_REMOTE_GROUP(comm, group)

   IN     comm         intercommunicator
   OUT    group        remote group corresponding
                       to comm

MPI_Comm_remote_group(MPI_Comm comm, MPI_Group *group)

MPI_COMM_REMOTE_GROUP(COMM, GROUP, IERROR)INTEGER COMM, GROUP, IERROR

MPI_COMM_REMOTE_GROUP returns the remote group in the intercommunicator. Note that the local group is give by MPI_COMM_GROUP.