:ref:`MPI_Comm_rank` |mdash| Determines the rank of the calling process in the communicator.
#include <mpi.h>
int MPI_Comm_rank(MPI_Comm comm, int *rank)
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_RANK(COMM, RANK, IERROR)
INTEGER COMM, RANK, IERROR
USE mpi_f08
MPI_Comm_rank(comm, rank, ierror)
TYPE(MPI_Comm), INTENT(IN) :: comm
INTEGER, INTENT(OUT) :: rank
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
comm
: Communicator (handle).
rank
: Rank of the calling process in group of comm (integer).ierror
: Fortran only: Error status (integer).
This function gives the rank of the process in the particular communicator's group. It is equivalent to accessing the communicator's group with :ref:`MPI_Comm_group`, computing the rank using :ref:`MPI_Group_rank`, and then freeing the temporary group via :ref:`MPI_Group_free`.
Many programs will be written with the manager-worker 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, :ref:`MPI_Comm_size` and :ref:`MPI_Comm_rank` are useful for determining the roles of the various processes of a communicator.
.. seealso::
* :ref:`MPI_Comm_group`
* :ref:`MPI_Comm_size`
* :ref:`MPI_Comm_compare`