mpi_comm_test_inter(3openmpi) [osx man page]

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)

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MPI_Comm_remote_group(3)						MPI						  MPI_Comm_remote_group(3)

NAME

       MPI_Comm_remote_group -	Accesses the remote group associated with  the given inter-communicator

SYNOPSIS

       int MPI_Comm_remote_group(MPI_Comm comm, MPI_Group *group)

INPUT PARAMETER

       comm   - Communicator (must be an intercommunicator) (handle)

OUTPUT PARAMETER

       group  - remote group of communicator (handle)

NOTES

       The user is responsible for freeing the group when it is no longer needed.

THREAD AND INTERRUPT SAFETY

       This  routine  is  thread-safe.	This means that this routine may be safely used by multiple threads without the need for any user-provided
       thread locks.  However, the routine is not interrupt safe.  Typically, this is due to the use of memory allocation routines such as  malloc
       or other non-MPICH runtime routines that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All  MPI  routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the end of the argument list.  ierr
       is an integer and has the same meaning as the return value of the routine in C.	In Fortran, MPI routines are subroutines, and are  invoked
       with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI  routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the function and Fortran routines in
       the last argument.  Before the value is returned, the current MPI error handler is called.  By default, this error handler aborts  the  MPI
       job.   The  error  handler  may	be  changed  with  MPI_Comm_set_errhandler  (for  communicators), MPI_File_set_errhandler (for files), and
       MPI_Win_set_errhandler (for RMA windows).  The MPI-1 routine MPI_Errhandler_set may be used but its  use  is  deprecated.   The	predefined
       error handler MPI_ERRORS_RETURN may be used to cause error values to be returned.  Note that MPI does not guarentee that an MPI program can
       continue past an error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
	      - No error; MPI routine completed successfully.
       MPI_ERR_COMM
	      - Invalid communicator.  A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank ).

SEE ALSO

       MPI_Group_free

LOCATION

       comm_remote_group.c

								     11/6/2010						  MPI_Comm_remote_group(3)

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