void send(void *buf, int count, int dest, int tag, int rank) {
    $message out = $message_pack(rank, dest, tag, buf, count*sizeof(double));
    $comm_enqueue(&MPI_COMM_WORLD, out);
  }

  void recv(void *buf, int count, int source, int tag, int rank) {
    $message in = $comm_dequeue(&MPI_COMM_WORLD, source, rank, tag);
    $message_unpack(in, buf, count*sizeof(double));
  }

  void reduce_send(void *buf, int count, int dest, int tag, int rank){
    $message out = $message_pack(rank, dest, tag, buf, count*sizeof(double));
    $comm_enqueue(&REDUCE_COMM, out);
  }

  void reduce_recv(void *buf, int count, int source, int tag, int rank){
    $message in = $comm_dequeue(&REDUCE_COMM, source, rank, tag);
    $message_unpack(in, buf, count*sizeof(double));
  }