!**********************************************************************
!   Derived datatypes, Send the last from 0 and store it as the first
!   row in processor 1
!     
!****************************************************************************
program datatypes

  include 'mpif.h'
  integer, parameter :: DP=kind(0.0D0)
  
  real(kind=DP),dimension(:,:),allocatable :: A
  integer :: n, myid, numprocs,nx,ny,row,col,count,blocklen,stride
  integer :: status,ierr
  
  call MPI_INIT( ierr )
  call MPI_COMM_RANK( MPI_COMM_WORLD, myid, ierr )
  call MPI_COMM_SIZE( MPI_COMM_WORLD, numprocs, ierr )
  
  nx=100; ny=150
  allocate(A(nx,ny));
  
  do col=1,ny
     do row=1,nx
        A(row,col)=col+(rank+1)*1000.0;
     end do
  end do
  
  ! Notice, in Fortran data is stored column-wise, 
  ! sending a row is then a problem
  
  count=ny; blocklen=1; stride=nx;
  call MPI_Type_vector(count,blocklen,stride,MPI_DOUBLE_PRECISION,newtype,ierr);
  call MPI_Type_commit(newtype,ierr);
  
  !* Send last row, notice the message length = 1 ! *!
  if (myid == 0) then
     call MPI_Send(A(nx,1), 1, newtype, 1, 111, MPI_COMM_WORLD,ierr)
     
  elseif (myid==1) then
     call MPI_Recv(A(1,1), 1, newtype, 0, 111, MPI_COMM_WORLD, status, ierr);
     do col=1,ny
        write(*,*) A(1,col)
     end do
  end if
  
  deallocate(A)
  call MPI_Type_free(newtype,ierr);
  call MPI_FINALIZE(ierr)
  
end program datatypes