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 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 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++ 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_Intercomm_create
       MPI_Comm_free