MPI_Intercomm_merge(3) Open MPI MPI_Intercomm_merge(3)
NAME
MPI_Intercomm_merge - Creates an intracommunicator from an intercommu-
nicator.
SYNTAX
C Syntax
#include <mpi.h>
int MPI_Intercomm_merge(MPI_Comm intercomm, int high,
MPI_Comm *newintracomm)
Fortran Syntax
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_INTERCOMM_MERGE(INTERCOMM, HIGH, NEWINTRACOMM, IERROR)
INTEGER INTERCOMM, NEWINTRACOMM, IERROR
LOGICAL HIGH
Fortran 2008 Syntax
USE mpi_f08
MPI_Intercomm_merge(intercomm, high, newintracomm, ierror)
TYPE(MPI_Comm), INTENT(IN) :: intercomm
LOGICAL, INTENT(IN) :: high
TYPE(MPI_Comm), INTENT(OUT) :: newintracomm
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
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 provide
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 argu-
ment, 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
4.1.2 Nov 24, 2021 MPI_Intercomm_merge(3)
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