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MPI_Comm_rank(3OpenMPI)                                                              MPI_Comm_rank(3OpenMPI)



NAME
       MPI_Comm_rank - Determines the rank of the calling process in the communicator.


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 communicator'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 pro-cesses processes
       cesses 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++ 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_Comm_group
       MPI_Comm_size
       MPI_Comm_compare




Open MPI 1.2                                   September 2006                        MPI_Comm_rank(3OpenMPI)