call MPI_SEND(square,1,MPI_REAL,0,99,MPI_COMM_WORLD,ierr)
                |    |    |     |  |        |         |
              send   |  type    | tag  communicator   |
             buffer  |   of    rank                 error
		     |  entry   of
		     |       destination
                  number
		    of
                  entries
		  to send