For Cartesian topologies, the function MPI_DIMS_CREATE helps
the user select a balanced distribution of processes per coordinate
direction, depending on the number of processes in the group to be
balanced and optional constraints that can be specified by the user.
One possible use of this function is to partition all the processes
(the size of
MPI_COMM_WORLD's group) into an * n *-dimensional topology.

MPI_DIMS_CREATE(nnodes, ndims, dims) IN nnodes number of nodes in a grid IN ndims number of cartesian dimensions INOUT dims integer array of size ndims specifying the number of nodes in each dimension.MPI_Dims_create(int nnodes, int ndims, int *dims)

MPI_DIMS_CREATE(NNODES, NDIMS, DIMS, IERROR)INTEGER NNODES, NDIMS, DIMS(*), IERROR

The entries in the array dims are set to describe a Cartesian
grid with ndims dimensions and a total of nnodes
nodes. The dimensions are set to be as close to each other as
possible, using an appropriate divisibility algorithm. The caller may
further constrain the operation of this routine by specifying elements
of array `dims`. If `dims[i]` is set to a positive number, the
routine will not modify the number of nodes in dimension `i`; only
those entries where `dims[i] = 0` are modified by the call.

Negative input values of `dims[i]` are erroneous.
An error will occur if `nnodes` is not a multiple of
.

For `dims[i]` set by the call, `dims[i]` will be ordered in
monotonically decreasing order. Array `dims` is suitable for use
as input to routine MPI_CART_CREATE.
MPI_DIMS_CREATE is local. Several sample calls are shown
in Example .

Fri Sep 1 06:16:55 EDT 1995