关于混合偏导数求导次序无关的条件

On the Conditions for Two Mixed Partial Derivatives of Order Two of a Function of Two Variables to be Equal

本文绘出了二元函数二阶混合偏导数求导次序无关的一个充分条件.

This article gives a sufficient condition about two stairs partial derivative of binary function that have not calculusing derivative to do with sequence.