kaki kia ik ki, 故(AB)=BA7 例41对于分块矩阵的转置有, A(AY (A B= (AB); B A B(A 上页1 1 1 , n n n ik kj ki jk jk ki k k k b a b a a b ′ ′ = = = ∑ ∑= = ∑ ( ) . T T T 故 AB = B A 例4.1 对于分块矩阵的转置有, ( ) ; ( ); . T T T T T T T T T T T A A A B A B B B A B A C C D B D ⎛ ⎞ ⎛ ⎞ ⎜ ⎟ ⎜ ⎟ = = ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎟⎟ ⎜ ⎟⎟ ⎜⎝ ⎠ ⎝ ⎠ ⎛ ⎞ ⎛ ⎞ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ =⎜ ⎟ ⎜ ⎟ ⎟ ⎜⎝ ⎠⎟ ⎜⎜ ⎟⎟ ⎝ ⎠