C	/*
C	* Illustrate the usage of MPI_SEND_RECV
C	* All the proc send message to the next proc simultaneously,
C	* and then receive message from the previous proc
C	*/

	program main
	include 'mpif.h'

	integer rank, tag
	integer ierr, nproc, dest
	integer sendbuf(1), recvbuf(1)
	integer status(MPI_STATUS_SIZE)

	tag = 0
	CALL MPI_INIT(ierr)
	CALL MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
	CALL MPI_COMM_SIZE(MPI_COMM_WORLD, nproc, ierr)

	dest = MOD ((rank + 1), nproc)
	print *, 'Proc ', rank, ': Sending message to ', dest, '...'
	IF (rank.EQ.0) THEN 
		CALL MPI_SENDRECV(sendbuf, 1, MPI_INTEGER, dest, tag, recvbuf, 1, MPI_INTEGER, nproc - 1, tag, MPI_COMM_WORLD, status, ierr);
	ELSE
		CALL MPI_SENDRECV(sendbuf, 1, MPI_INTEGER, dest, tag, recvbuf, 1, MPI_INTEGER, rank - 1, tag, MPI_COMM_WORLD, status, ierr);
	END IF 
	print *, 'Proc ', rank, ': Receive message from ', status(MPI_SOURCE), '...'

	call MPI_FINALIZE(ierr)
	end