AB= 要求:A的列划分方式与B的行划分方式相同. 10:00 01:00 E O 例1A= 12:10|A2,E 11:01 10:10 0-42 B. E B B. B 0:10 B E 12:01 AB= A21B1+B21A21+B2 -11:31 A 转置 特点:“大转 小转 5准对角矩阵:设A1,A2,…,A都是方阵记 A=diag(A1,42,…,A,)= 性质:(1)detA=(det41)(det2)…(det4,) (2)A可逆兮A1(i=1,2,…,s)可逆12           = s sr r C C C C AB     1 11 1 要求： A 的列划分方式与 B 的行划分方式相同． 例 1             − = 1 1 0 1 1 2 1 0 0 1 0 0 1 0 0 0 A       = A E E O 21             − − − = 1 1 2 0 1 0 4 1 1 2 0 1 1 0 1 0 B       = 21 22 11 B B B E       + + = 21 11 21 21 22 11 A B B A B B E AB             − − − = 1 1 3 1 2 4 3 3 1 2 0 1 1 0 1 0 4. 转置：            = s sr r m n A A A A A     1 11 1 ,           = T T 1 T 1 T 11 T r sr s A A A A A     特点：“大转”+“小转” 5. 准对角矩阵：设 A1 , A2 , As  , 都是方阵, 记             = = s s A A A A A A A   2 1 1 2 diag( , , , ) 性质：(1) det (det )(det ) (det ) A = A1 A2  As (2) A 可逆 A (i 1,2, ,s)  i =  可逆