MPI_Intercomm_merge(3)

NAME
     MPI_Intercomm_merge - Creates an intracommuncator from an
     intercommunicator

SYNOPSIS
     C:

          #include <mpi.h>

          int MPI_Intercomm_merge ( comm, high, comm_out )
          MPI_Comm  comm;
          int       high;
          MPI_Comm *comm_out;


     C++:

          #include <mpi.h>

          Intracomm Intercomm::Merge(
          bool              high) const


     Fortran:

          INCLUDE "mpif.h" (or USE MPI)

          INTEGER intercomm, intracomm, ierror
          LOGICAL high

          CALL MPI_INTERCOMM_MERGE(intercomm, high, intracomm, ierror)


STANDARDS
     This release implements the MPI 1.2 standard, as documented by the MPI
     Forum in the spring 1997 release of MPI:  A Message Passing Interface
     Standard.

DESCRIPTION
     The MPI_Intercomm_merge routine creates an intracommuncator from an
     intercommunicator.  This routine accepts the following parameters:

     comm      Specifies  the intercommunicator

     high      Specifies a value used to order the groups of the two
               intracommunicators within comm when creating the new
               communicator

     comm_out  Returns the created intracommunicator
     ierror    Specifies the return code value for successful completion,
               which is in MPI_SUCCESS.  MPI_SUCCESS is defined in the mpif.h
               file.

NOTES
     The following algorithm is used to create the intracommunicator:

     1.   Allocate two contexts.

     2.   Swap high values between local and remote group leaders.

     3.   Determine the high value.

     4.   Merge the two groups and make the intracommunicator.