mpi.cart.shift: MPI\_Cart\_shift
In snoweye/Rmpi_PROF: Interface (Wrapper) to MPI (Message-Passing Interface)

Description Usage Arguments Details Value Author(s) References See Also Examples

mpi.cart.shift shifts the Cartesian topology in both manners, displacement and direction.

1	mpi.cart.shift(comm=3, direction, disp)

`comm`	Communicator with Cartesian structure
`direction`	Coordinate dimension of the shift
`disp`	displacement (>0 for upwards or left shift, <0 for downwards or right shift)

mpi.cart.shift provides neighbor ranks from given direction and displacement. The direction argument indicates the dimension of the shift. direction=1 means the first dim, direction=2 means the second dim, etc. disp=1 or -1 provides immediate neighbor ranks and disp=2 or -2 provides neighbor's neighbor ranks. Negative ranks mean out of boundary. They correspond to mpi.proc.null.

mpi.cart.shift returns a vector containing information regarding the rank of the source process and rank of the destination process.

Alek Hunchak and Hao Yu

http://www.lam-mpi.org/, http://www-unix.mcs.anl.gov/mpi/www/www3/

mpi.cart.create,mpi.proc.null

## Not run: 
#Need at least 9 slaves
mpi.bcast.cmd(mpi.cart.create(1,c(3,3),c(F,T)))
mpi.cart.create(1,c(3,3),c(F,T))
mpi.remote.exec(mpi.cart.shift(3,2,1))#get neighbor ranks
mpi.remote.exec(mpi.cart.shift(3,1,1))

## End(Not run)