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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 constructors) 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++ functions 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)