osx man page for mpi_intercomm_create

MPI_Intercomm_create(3OpenMPI)											    MPI_Intercomm_create(3OpenMPI)

NAME
       MPI_Intercomm_create - Creates an intercommuncator from two intracommunicators.

SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Intercomm_create(MPI_Comm local_comm, int local_leader,
	    MPI_Comm peer_comm, int remote_leader, int tag, MPI_Comm *newintercomm)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_INTERCOMM_CREATE(LOCAL_COMM, LOCAL_LEADER, PEER_COMM,
		 REMOTE_LEADER, TAG, NEWINTERCOMM, IERROR)
	    INTEGER   LOCAL_COMM, LOCAL_LEADER, PEER_COMM, REMOTE_LEADER
	    INTEGER   TAG, NEWINTERCOMM, IERROR

C++ Syntax
       #include <mpi.h>
       Intercomm Intracomm::Create_intercomm(int local_leader, const
	    Comm& peer_comm, int remote_leader, int tag) const

INPUT PARAMTERS
       local_comm
		 The communicator containing the process that initiates the inter-communication (handle).

       local_leader
		 Rank of local group leader in local_comm (integer).

       peer_comm "Peer" communicator; significant only at the local_leader (handle).

       remote_leader
		 Rank of remote group leader in peer_comm; significant only at the local_leader (integer).

       tag	 Message tag used to identify new intercommunicator (integer).

OUTPUT PARAMETERS
       newintercomm
		 Created intercommunicator (handle).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION
       This  call creates an intercommunicator. It is collective over the union of the local and remote groups. Processes should provide identical
       local_comm and local_leader arguments within each group. Wildcards are not permitted for remote_leader, local_leader, and tag.

       This call uses point-to-point communication with communicator peer_comm, and with tag tag between the leaders. Thus,  care  must  be  taken
       that there be no pending communication on peer_comm that could interfere with this communication.

       If  multiple  MPI_Intercomm_creates  are  being made, they should use different tags (more precisely, they should ensure that the local and
       remote leaders are using different tags for each MPI_intercomm_create).

NOTES
       We recommend using a dedicated peer communicator, such as a duplicate of MPI_COMM_WORLD, to avoid trouble with peer communicators.

       The MPI 1.1 Standard contains two mutually exclusive comments on the input intracommunicators.  One says that their repective  groups  must
       be  disjoint;  the  other  that	the leaders can be the same process.  After some discussion by the MPI Forum, it has been decided that the
       groups must be disjoint.  Note that the reason given for this in the standard is not the reason for this choice; rather, the  other  opera-
       tions on intercommunicators (like MPI_Intercomm_merge ) do not make sense if the groups are not disjoint.

ERRORS
       Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func-
       tions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception  mechanism
       will be used to throw an MPI:Exception object.

       Before  the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for
       I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN  may	be
       used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO
       MPI_Intercomm_merge
       MPI_Comm_free
       MPI_Comm_remote_group
       MPI_Comm_remote_size

Open MPI 1.2							  September 2006				    MPI_Intercomm_create(3OpenMPI)