osx man page for mpi_comm_dup

MPI_Comm_dup(3OpenMPI)													    MPI_Comm_dup(3OpenMPI)

NAME
       MPI_Comm_dup  -	Duplicates an existing communicator with all its cached information.

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

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_COMM_DUP(COMM, NEWCOMM, IERROR)
	    INTEGER   COMM, NEWCOMM, IERROR

C++ Syntax
       #include <mpi.h>
       Intracomm Intracomm::Dup() const

       Intercomm Intercomm::Dup() const

INPUT PARAMETER
       comm	 Communicator (handle).

OUTPUT PARAMETERS
       newcomm	 Copy of comm (handle).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION
       MPI_Comm_dup  duplicates  the existing communicator comm with associated key values. For each key value, the respective copy callback func-
       tion determines the attribute value associated with this key in the new communicator; one particular action that a copy callback  may  take
       is to delete the attribute from the new communicator. Returns in newcomm a new communicator with the same group, any copied cached informa-
       tion, but a new context (see Section 5.7.1 of the MPI-1 Standard, "Functionality").

NOTES
       This operation is used to provide a parallel library call with a duplicate communication space that has the same properties as the original
       communicator.  This  includes  any attributes (see below) and topologies (see Chapter 6, "Process Topologies," in the MPI-1 Standard). This
       call is valid even if there are pending point-to-point communications involving the communicator comm. A  typical  call	might  involve	an
       MPI_Comm_dup at the beginning of the parallel call, and an MPI_Comm_free of that duplicated communicator at the end of the call. Other mod-
       els of communicator management are also possible.

       This call applies to both intra- and intercommunicators.

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.

Open MPI 1.2							  September 2006					    MPI_Comm_dup(3OpenMPI)