mpi_intercomm_merge(3openmpi) [osx man page]

MPI_Intercomm_merge(3OpenMPI)											     MPI_Intercomm_merge(3OpenMPI)

NAME

       MPI_Intercomm_merge - Creates an intracommunicator from an intercommunicator.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Intercomm_merge(MPI_Comm intercomm, int high,
	    MPI_Comm *newintracomm

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_INTERCOMM_MERGE(INTERCOMM, HIGH, NEWINTRACOMM, IERROR)
	    INTEGER   INTERCOMM, NEWINTRACOMM, IERROR
	    LOGICAL   HIGH

C++ Syntax
       #include <mpi.h>
       Intracomm Intercomm::Merge(bool high) const

INPUT PARAMETERS

       intercomm Intercommunicator (type indicator).

       high	 Used to order the groups of the two intracommunicators within comm when creating the new communicator (type indicator).

OUTPUT PARAMETERS

       newintracomm
		 Created intracommunicator (type indicator).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       This  function  creates an intracommunicator from the union of the two groups that are associated with intercomm. All processes should pro-
       vide the same high value within each of the two groups. If processes in one group provide the value high = false and processes in the other
       group  provide the value high = true, then the union orders the "low" group before the "high" group. If all processes provide the same high
       argument, then the order of the union is arbitrary. This call is blocking and collective within the union of the two groups.

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_create
       MPI_Comm_free

Open MPI 1.2							  September 2006				     MPI_Intercomm_merge(3OpenMPI)

MPI_Comm_test_inter(3OpenMPI)											     MPI_Comm_test_inter(3OpenMPI)

NAME

       MPI_Comm_test_inter  - Tests to see if a comm is an intercommunicator.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Comm_test_inter(MPI_Comm comm, int *flag)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_COMM_TEST_INTER(COMM, FLAG, IERROR)
	    INTEGER   COMM, IERROR
	    LOGICAL   FLAG

C++ Syntax
       #include <mpi.h>
       bool Comm::Is_inter() const

INPUT PARAMETER

       comm	 Communicator (handle).

OUTPUT PARAMETERS

       flag	(Logical.)

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       This  local routine allows the calling process to determine the type of a communicator. It returns true for an intercommunicator, false for
       an intracommunicator.

       The type of communicator also affects the value returned by three other functions.  When dealing with an intracommunicator (enables  commu-
       nication  within a single group), the functions listed below return the expected values, group size, group, and rank.  When dealing with an
       inter-communicator, however, they return the following values:

       MPI_Comm_size  Returns the size of the local group.
       MPI_Comm_group Returns the local group.
       MPI_Comm_rank  Returns the rank in the local group.

       To return the remote group and remote group size of an inter-communicator, use the  MPI_Comm_remote_group  and  MPI_Comm_remote_size  func-
       tions.

       The  operation  MPI_Comm_compare  is  valid for intercommunicators. Both communicators must be either intra- or intercommunicators, or else
       MPI_UNEQUAL results. Both corresponding local and remote groups must compare correctly to get the results MPI_CONGRUENT and MPI_SIMILAR. In
       particular, it is 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: MPI_Comm_remote_size, MPI_Comm_remote_group.

       The intercommunicator accessors (MPI_Comm_test_inter, MPI_Comm_remote_size, MPI_Comm_remote_group) are all local operations.

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_remote_group
       MPI_Comm_remote_size
       MPI_Intercomm_create
       MPI_Intercomm_merge

Open MPI 1.2							  September 2006				     MPI_Comm_test_inter(3OpenMPI)