MPI_Comm_rank(3)		   Open MPI		      MPI_Comm_rank(3)

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.

SEE ALSO
       MPI_Comm_group
       MPI_Comm_size
       MPI_Comm_compare

1.7.4				 Feb 04, 2014		      MPI_Comm_rank(3)

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