) 中图学技术大荸学系 University of Science and Technology of China DEPARTMENT OF MATHEMATICS 近似f(1)≈f(2) f(x-Ln,(x)x- f(x-L(x)x-x n+1 X-x X-x →f(x) n+Ln(x)+ n+1 n+1 X-x →f(x)-Ln(x)≈ X X n+1数 学 系 University of Science and Technology of China DEPARTMENT OF MATHEMATICS 近似 ( ) ( ) 2 ( 1) 1 ( 1)   + +  n n f f 则 ( ( )) ~ ( ) ( ) ( ) ( ) ~ ( ) ( ) ( ) ~ ( ) ( ) ( ) 0 1 0 1 0 0 0 1 1 1 0 L x L x x x x x f x L x L x x x x x L x x x x x f x x x x x f x L x f x L x n n n n n n n n n n n n − − −  −  − − + − −   − −  − − + + + + +