h1h2…b b, x 2 1x+b141+b122+…+b,2 x2=x2+b211+b2l2+…+b2 ppb u b u b p up x x 1 =  1 1 + 1 1 1 + 1 2 2 ++ 1 b u b u b p up x x 2 =  2 2 + 2 1 1 + 2 2 2 ++ 2