A = ( d_0 e_0 ) ( e_0 d_1 e_1 ) ( e_1 d_2 e_2 ) ( e_2 d_3 )
A = ( d_0 e_0 e_3 ) ( e_0 d_1 e_1 ) ( e_1 d_2 e_2 ) ( e_3 e_2 d_3 )