Example of splitting a communicator

Example of Communicator Splitting

• Assume communicator with group of 8 processes

  

  call mpi_comm_rank (comm, rank, ierr)
  call mpi_comm_size (comm, size, ierr)
  color = 2*rank/size
  key   = size - rank - 1
  call mpi_comm_split (comm, color, key, 
                       newcomm, ierr)