左右两边同乘以因子(ss;),再令s=(i1,2,…;n) N(S k =(s-S (i=1,2,…m) D(S) [F(S)=L[]+L[-2-]+…+L[ S-S ke”+k2e+…+k,e”"]2(左右两边同乘以因子( s-si )，再令s =si ( i=1,2,…,n ) ( 1,2, ) ( ) ( ) ( ) i n D s N s k s s i s s i = − i =  = [ ( )] [ ] [ ] [ ] 1 2 1 2 1 1 1 1 n n s s k L s s k L s s k L F s L − + + − + − = − − −  − [ ] ( ) 1 2 1 2 k e k e k e t s t n s t s t n = + ++ 