The functions in this section translate to/from the rank and the Cartesian topology coordinates. These calls are local.
MPI_Cart_rank(MPI_Comm comm, int *coords, int *rank)
MPI_CART_RANK(COMM, COORDS, RANK, IERROR)INTEGER COMM, COORDS(*), RANK, IERROR
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.
coords is an array of size ndims as returned by
MPI_CARTDIM_GET.
For the example in Figure 
,coords = (1,2)
would return rank = 6.
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.
If the topology in Figure is periodic in both
dimensions (torus), then coords = (4,6) would also return
rank = 6. Out-of-range
coordinates are erroneous for non-periodic dimensions.
MPI_Cart_coords(MPI_Comm comm, int rank, int maxdims, int *coords)
MPI_CART_COORDS(COMM, RANK, MAXDIMS, COORDS, IERROR)INTEGER COMM, RANK, MAXDIMS, COORDS(*), IERROR
MPI_CART_COORDS is the rank-to-coordinates translator. It
is the inverse mapping of MPI_CART_RANK. maxdims
is at least as big as ndims as returned by
MPI_CARTDIM_GET. For the example in
Figure , rank = 6 would return
coords = (1,2)