4n,+ N=16=42 k=4k,+k X(k)=∑∑x(n1,n0)WW 0=0n 1)X1(k,n)=∑x(n,n) 0 2)X1(k2n0)=X1(k0,n0)WN 3)X2(kk)=∑X1(k0,n0)W2 N  16  4 1 0 1 0 4 4 n n n k k k            1 0 0 0 0 1 0 1 3 3 4 4 1 0 0 0 , n k n k n k N N N n n X k x n n W W W          1 0 1 3 1 0 0 1 0 4 0 1) , , n k n X k n x n n W        0 0 ' 1 0 0 1 0 0 2) , , n k X N k n  X k n W     0 1 0 3 ' 2 0 1 1 0 0 4 0 3) , , n k n X k k X k n W   