osx man page for mpi_comm_create

MPI_Comm_create(3OpenMPI)												 MPI_Comm_create(3OpenMPI)

NAME
       MPI_Comm_create - Creates a new communicator.

SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Comm_create(MPI_Comm comm, MPI_Group group, MPI_Comm *newcomm)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_COMM_CREATE(COMM, GROUP, NEWCOMM, IERROR)
	    INTEGER   COMM, GROUP, NEW, IERROR

C++ Syntax
       #include <mpi.h>
       MPI::Intercomm MPI::Intercomm::Create(const Group& group) const

       MPI::Intracomm MPI::Intracomm::Create(const Group& group) const

INPUT PARAMETER
       comm	 Communicator (handle).

       group	 Group, which is a subset of the group of comm (handle).

OUTPUT PARAMETERS
       newcomm	 New communicator (handle).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION
       This  function creates a new communicator newcomm with communication group defined by group and a new context. The function sets newcomm to
       a new communicator that spans all the processes that are in the group.	It sets newcomm to MPI_COMM_NULL for processes that are not in the
       group.	 The  call  is	erroneous if not all group arguments have the same value, or if group is not a subset of the group associated with
       comm. Note that the call must be executed by all processes in comm, even if they do not belong to the new group.

NOTES
       MPI_Comm_create provides a means of making a subset of processes for the purpose of separate MIMD computation, with separate  communication
       space.  newcomm,  which	is created by MPI_Comm_create, can be used in subsequent calls to MPI_Comm_create (or other communicator construc-
       tors) to further subdivide a computation into parallel sub-computations. A more general service is provided by MPI_Comm_split.

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_Comm_split

       MPI_Intercomm_create

Open MPI 1.2							  September 2006					 MPI_Comm_create(3OpenMPI)