n
n-1
n+1
2n-1
maximum of n,d
n+d
nd
nd/2
A-2 , B-4 , C-1 , D-3
A-3 , B-4 , C-1 , D-2
A-3 , B-4 , C-2 , D-1
A-4 , B-1 , C-2 , D-3
n x (i -1) + j
m x (j -1) + i
m x (n-j) + j
n x (m-i) + j
higher dimension
many non-zero entries
many zero entries
higher dimension and many non-zero entries