recvptr + rank * recv_count * extent,
recv_count, recv_type, rank, tag, comm, &status);
for (i = 1; i < num_procs; i++) {
src = (rank - i + num_procs) % num_procs;
dst = (rank + i) % num_procs;
recvptr + rank * recv_count * extent,
recv_count, recv_type, rank, tag, comm, &status);
for (i = 1; i < num_procs; i++) {
src = (rank - i + num_procs) % num_procs;
dst = (rank + i) % num_procs;