MPI_Comm_rank(3)                   Open MPI                   MPI_Comm_rank(3)



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 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++
       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




1.4.1                            Jan 14, 2010                 MPI_Comm_rank(3)
