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MPI_Comm_rank(3) man page (version 1.2.9)

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NAME

       MPI_Comm_rank  - Determines the rank of the calling process in the com-
       municator.

SYNTAX


C Syntax

       #include <mpi.h>
       int MPI_Comm_rank(MPI_Comm comm, int *rank)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_COMM_RANK(COMM, RANK, IERROR)
            INTEGER   COMM, RANK, IERROR

C++ Syntax

       #include <mpi.h>
       int Comm::Get_rank() const

INPUT PARAMETERS

       comm      Communicator (handle).

OUTPUT PARAMETERS

       rank      Rank of the calling process in group of comm (integer).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       This function gives the rank of the process in the particular  communi-
       cator's  group.  It is equivalent to accessing the communicator's group
       with MPI_Comm_group, computing the rank using MPI_Group_rank, and  then
       freeing the temporary group via MPI_Group_free.

       Many  programs  will  be written with the master-slave model, where one
       process (such as the rank-zero process) will play a  supervisory  role,
       and the other processes will serve as compute nodes. In this framework,
       MPI_Comm_size and MPI_Comm_rank are useful for determining the roles of
       the various processes of a communicator.

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.

Open MPI 1.2                    September 2006         MPI_Comm_rank(3OpenMPI)

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