repeating step d to calculate row values for rows 1 to 2N+1 and storing the row value for {HEAD ~ each} of {TAIL ~ the 2N+1 to 1 rows} in a respective one of memory locations 2N+1 to 1 
of
repeating step d to calculate row values for rows 1 to 2N+1 and storing the row value for { HEAD ~ each } of { TAIL ~ the 2N+1 to 1 rows } in a respective one of memory locations 2N+1 to 1
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH