u a 1b 2b u1 HI H 12 H21 H Ib 22LL2 b z1 uia u1b Hub HI 126 b 12 12 a z26 H2la H22alu2d H21b H22bLu2b Hula hi 11b Z1 Hela h 21b H 22b z2 Ha Ha= lla H、xH2b 116 Hi h2la h 22a H 22bNa + i1a + i2a u2a u1a Nb + i1b + i2b u1b u2b + u2 + u1 i1 i2 • • • 2 1 u i 21 22 11 12 H H H H = 2 1 i u 2 1 i u = a a i u 2 1 + b b i u 2 1 a a u i 2 1 a a a a H H H H 21 22 11 12 = + b b u i 2 1 b b b b H H H H 21 22 11 12 a a a a H H H H 21 22 11 12 = + 2 1 u i b b b b H H H H 21 22 11 12 a a a a H H H H 21 22 11 12 = + b b b b H H H H 21 22 11 12 21 22 11 12 H H H H