bra12a13其中3an2D, =[b,1b3a132a33b1b63a13D, =a23a31a33663aiD, =a21a31a3282.1引言A§2.1 引言 其中 1 12 13 1 2 22 23 3 32 33 , b a a D b a a b a a = 11 1 13 2 21 2 23 31 3 33 , a b a D a b a a b a = 11 12 1 3 21 22 2 31 32 3 . a a b D a a b a a b =