.. _mpi_cart_rank:

MPI_Cart_rank
=============

.. include_body

:ref:`MPI_Cart_rank` |mdash| Determines process rank in communicator given Cartesian
location.

SYNTAX
------

C Syntax
^^^^^^^^

.. code-block:: C

   #include <mpi.h>

   int MPI_Cart_rank(MPI_Comm comm, int coords[], int *rank)

Fortran Syntax
^^^^^^^^^^^^^^

.. code-block:: Fortran

   USE MPI
   ! or the older form: INCLUDE 'mpif.h'

   MPI_CART_RANK(COMM, COORDS, RANK, IERROR)
       INTEGER COMM, COORDS(*), RANK, IERROR

Fortran 2008 Syntax
^^^^^^^^^^^^^^^^^^^

.. code-block:: Fortran

   USE mpi_f08

   MPI_Cart_rank(comm, coords, rank, ierror)
       TYPE(MPI_Comm), INTENT(IN) :: comm
       INTEGER, INTENT(IN) :: coords(*)
       INTEGER, INTENT(OUT) :: rank
       INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS
----------------

* ``comm`` : Communicator with Cartesian structure (handle).
* ``coords`` : Integer array (of size ndims, which was defined by
   :ref:`MPI_Cart_create` call) specifying the Cartesian coordinates of a
   process.

OUTPUT PARAMETER
----------------

* ``rank`` : Rank of specified process (integer).
* ``ierror`` : Fortran only: Error status (integer).

DESCRIPTION
-----------

For a process group with Cartesian structure, the function :ref:`MPI_Cart_rank`
translates the logical process coordinates to process ranks as they are
used by the point-to-point routines. For dimension i with periods(i) =
true, if the coordinate, coords(i), is out of range, that is, coords(i)
< 0 or coords(i) >= dims(i), it is shifted back to the interval 0 =<
coords(i) < dims(i) automatically. Out-of-range coordinates are
erroneous for nonperiodic dimensions.

ERRORS
------

.. include:: ./ERRORS.rst

.. seealso::
   * :ref:`MPI_Cart_create`