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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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