A.[1,-j,-1,j] B.[1,j,-1,-j] C.[j,-1,-j,1] D.[-1,j,1,-j]
A.N B.1 C.W D.W
A.X(k)=-X(k) B.X(k)=X*(k) C.X(k)=X*(-k) D.X(k)=X(N-k)