openmpi/ompi/mpi/man/man3/MPI_Cart_rank.md

Name

MPI_Cart_rank - Determines process rank in communicator given Cartesian location.

Syntax

C Syntax

#include <mpi.h>

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

Fortran Syntax

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

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

Fortran 2008 Syntax

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 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 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

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. 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_Cart_create(3)