call MPI_GATHER(iarray2,4,MPI_INTEGER,iarray1,4,MPI_INTEGER,0,MPI_COMM_WORLD,ierr)
                   |    |    |           |    |      |      |       |         |
                  send  |   type         |    |     type    |   communicator  |
                 buffer |    of       receive |      of     |               error
	                |   send       buffer |    receive  |
		        |  elements           |    elements |
                      number               number           |      
		        of                   of        destination
                     elements             elements
		     to send             to receive