bionic (3) MPI_Intercomm_create.3.gz

NAME

       MPI_Intercomm_create -  Creates an intercommuncator from two intracommunicators

SYNOPSIS

       int MPI_Intercomm_create(MPI_Comm local_comm, int local_leader,
                              MPI_Comm peer_comm, int remote_leader, int tag,
                              MPI_Comm *newintercomm)

INPUT PARAMETERS

       local_comm
              - Local (intra)communicator
       local_leader
              - Rank in local_comm of leader (often 0)
       peer_comm
              -  Communicator  used  to  communicate  between  a  designated  process in the other communicator.
              Significant only at the process in local_comm with rank local_leader .

       remote_leader
              - Rank in peer_comm of remote leader (often 0)
       tag    - Message tag to use in constructing  intercommunicator;  if  multiple  MPI_Intercomm_creates  are
              being  made,  they  should  use  different  tags (more precisely, ensure that the local and remote
              leaders are using different tags for each MPI_intercomm_create ).

OUTPUT PARAMETERS

       newintercomm
              - Created intercommunicator

NOTES

       peer_comm is significant only for the process designated the local_leader in the local_comm .

       The MPI 1.1 Standard contains two mutually exclusive comments on the input intercommunicators.  One  says
       that  their repective groups must be disjoint; the other that the leaders can be the same process.  After
       some discussion by the MPI Forum, it has been decided that the groups must be disjoint.   Note  that  the
       reason  given for this in the standard is not the reason for this choice; rather, the other operations on
       intercommunicators (like MPI_Intercomm_merge ) do not make sense if the groups are not disjoint.

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 ).
       MPI_ERR_TAG
              -  Invalid  tag  argument.   Tags must be non-negative; tags in a receive ( MPI_Recv , MPI_Irecv ,
              MPI_Sendrecv , etc.) may also be MPI_ANY_TAG .  The largest tag value is available through the the
              attribute MPI_TAG_UB .

       MPI_ERR_INTERN
              - This error is returned when some part of the MPICH implementation is unable to acquire memory.
       MPI_ERR_RANK
              - Invalid source or destination rank.  Ranks must be between zero and the size of the communicator
              minus one; ranks in a receive  (  MPI_Recv  ,  MPI_Irecv  ,  MPI_Sendrecv  ,  etc.)  may  also  be
              MPI_ANY_SOURCE .

SEE ALSO

       MPI_Intercomm_merge, MPI_Comm_free, MPI_Comm_remote_group,
       MPI_Comm_remote_size

                                                   11/12/2016                            MPI_Intercomm_create(3)