program struct
      include 'mpif.h'

      integer NELEM
      parameter(NELEM=25)
      integer numtasks, rank, source, dest, tag, i,  ierr
      integer stat(MPI_STATUS_SIZE)

      type Particle
      sequence
      real*4 x, y, z, velocity
      integer n, type
      end type Particle

      type (Particle) p(NELEM), particles(NELEM)
      integer particletype, oldtypes(0:1), blockcounts(0:1), 
     &        offsets(0:1), extent

C     *----------------*
C    * Initialize MPI *
C   *----------------*

      call MPI_INIT(ierr)

C     *------------------------------------------------------*
C    * Get my rank in the MPI_COMM_WORLD communicator group *
C   *------------------------------------------------------*

      call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)

C     *-------------------------------------------------------*
C    * Get the size of the MPI_COMM_WORLD communicator group *
C   *-------------------------------------------------------*

      call MPI_COMM_SIZE(MPI_COMM_WORLD, numtasks, ierr)

C     *---------------------------------------------------------------*
C    * Setup description of the 4 MPI_FLOAT fields x, y, z, velocity *
C   *---------------------------------------------------------------*

      offsets(0) = 0
      oldtypes(0) = MPI_REAL
      blockcounts(0) = 4

C      *----------------------------------------------------------------*
C     * Setup description of the 2 MPI_INT fields n, type              *
C    * Need to first identify the offset by getting size of MPI_FLOAT *
C   *----------------------------------------------------------------*

      call MPI_TYPE_EXTENT(MPI_REAL, extent, ierr)
      offsets(1) = 4 * extent
      oldtypes(1) = MPI_INTEGER
      blockcounts(1) = 2

C     *------------------------------------------*
C    * Now define structured type and commit it *
C   *------------------------------------------*

      call MPI_TYPE_STRUCT(2, blockcounts, offsets, oldtypes, 
     &                     particletype, ierr)
      call MPI_TYPE_COMMIT(particletype, ierr)

C     *-------------------------------------------------------------*
C    * Initialize the particle array and then send it to each task *
C   *-------------------------------------------------------------*
  
      tag = 1
      if (rank .eq. 0) then
        do 10 i=0, NELEM-1
        particles(i) = Particle ( 1.0*i, -1.0*i, 1.0*i, 
     &                  0.25, i, mod(i,2) )
  10    continue

        do 20 i=0, numtasks-1
        call MPI_SEND(particles, NELEM, particletype, i, tag, 
     &                 MPI_COMM_WORLD, ierr)
 20     continue
      endif

C     *----------------------------------------------------------------*
C    * Each task receives the particle array and stores it in p array *
C   *----------------------------------------------------------------*

      source = 0
      call MPI_RECV(p, NELEM, particletype, source, tag, 
     &              MPI_COMM_WORLD, stat, ierr)

C     *-------------------------------------*
C    * Print a sample of what was received *
C   *-------------------------------------*

      print *, 'rank= ',rank,p(3)

C     *------------------------*
C    * Free derived data type *
C   *------------------------*

      call MPI_TYPE_FREE(particletype, ierr)

C     *--------------*
C    * Finalize MPI *
C   *--------------*

      call MPI_FINALIZE(ierr)

      end