+图钭学技术大荸数学系 University of Science and Technology of china DEPARTMENT OF MATHEMATICS 中心差商 f(x0)≈ f(ro+h)-f(xo-h 2h 0 h 0 Xoth数 学 系 University of Science and Technology of China DEPARTMENT OF MATHEMATICS h f x h f x h f x 2 ( ) ( ) '( ) 0 0 0 + − −  中心差商 x0 -h x0 x0+h