MPI_CART_MAP, MPI_Cart_map

Purpose

Computes placement of tasks on the physical processor.

C synopsis

#include <mpi.h>
MPI_Cart_map(MPI_Comm comm,int ndims,int *dims,int *periods,
             int *newrank);

C++ synopsis

#include mpi.h
int MPI::Cartcomm::Map(int ndims, const int dims[],
                       const bool periods[]) const;

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_CART_MAP(INTEGER COMM,INTEGER NDIMS,INTEGER DIMS(*),
             INTEGER PERIODS(*),INTEGER NEWRANK,INTEGER IERROR)

Parameters

comm
     is the input communicator (handle) (IN)

ndims
     is the number of dimensions of the cartesian structure (integer) (IN)

dims
     is an integer array of size ndims specifying the number of tasks in
     each coordinate direction (IN)

periods
     is a logical array of size ndims specifying the periodicity in each
     coordinate direction (IN)

newrank
     is the reordered rank or MPI_UNDEFINED if the calling task does not
     belong to the grid (integer) (OUT)

IERROR
     is the FORTRAN return code. It is always the last argument.

Description

MPI_CART_MAP allows MPI to compute an optimal placement for the calling
task on the physical processor by reordering the tasks in comm.

Notes

The rank determined by MPI_CART_MAP depends on the distribution of task per
node. The value may or may not match rank in MPI_COMM_WORLD.

Errors

MPI not initialized

MPI already finalized

Invalid communicator

Invalid communicator type
     must be intracommunicator

Invalid ndims
     ndims < 1 or ndims > groupsize

Invalid dimension
     ndims[i] <= 0

Invalid grid size
     n< 0 or n > groupsize, where n is the product of dims[i]