The indicial expressions referred to above are linear functions of the cell-location-coordinate indices, IX, IY and IZ; and the coefficients in the linear functions involve the total numbers of cells in these three coordinate directions, namely NX, NY and NZ.
The indicial expressions are:
IY increasing
^ | NY 2*NY 3*NY ......... (NX-1)*NY NX*NY | NY-1 2*NY-1 NX*NY-1 | NY-2 . . | . . . | . . . | . . . | 4 . . | 3 NY+3 . | 2 NY+2 . | 1 NY+1 2*NY+1 ...................... (NX-1)*NY+1 | -------------------------------------------------> IX increasingwbs