program pingpong                          !!!     10-June-2005

c....... This program send the own processor number to the other processor
c....... (run with only 2 processors!) 
c....... WRONG VERSION!! should not work

        include 'mpif.h'

	integer status(MPI_STATUS_SIZE)

c........initialize MPI
        call mpi_init(ierr)
        call mpi_comm_rank(mpi_comm_world,iam,ierr)
        call mpi_comm_size(mpi_comm_world,nproc,ierr)

c........set an ID value for the message tag 
	itag=99
        icount=1
	isbuf = iam

	if (iam.eq.0) then
         idest=1
         isource=1
	endif

	if (iam.eq.1) then
         idest=0
         isource=0
   	endif

        CALL MPI_RECV(irbuf, icount, MPI_INTEGER, isource, itag,
     1                 MPI_COMM_WORLD, status, ierr)
	PRINT*, "TASK #", iam, " received ", irbuf 

	PRINT*, "TASK #", iam, " sent ", isbuf
        CALL MPI_SEND(isbuf, icount, MPI_INTEGER, idest, itag,  
     1                 MPI_COMM_WORLD, ierr)



c........close out MPI
	call mpi_finalize(ierr)

        stop
        end