无界函数的导数逼近

Derivativc-approximation of unbounded function

利用扩展乘数法，将Ｓ，Ｎ．Ｂｅｒｎｓｔｅｉｎ插值算子加以扩展，用其逼近Ｃ￣２（－∞，＋∞）上的导函数，得到其收敛阶为Ｏ（ａ＿ｎｌｎｎ／ｎ）。

Applying the method of multiple-enlargement to S.N. Bernstein interpola-tion operator and approximating this operator to the derivative of unbounded function on C￣2(-∞,+∞).It’s covergence order is O(α_nlnn/n).