利用方向导数探讨多元函数的单调性与极值

Multi-function Monotone and Extreme in Directional Derivative

将一元函数的单调性推广到多元函数上,给出了多元函数单调性的定义,利用方向导数探讨了多元函数关于方向导数的中值公式与多元函数单调性的判定法则,并利用该法则推出了求多元函数的极值的方法.

The monotone of one variable was extended to the multi-function to define the multi-function monotone,and the formula of directional derivative and the rule of judging multi-function monotone were explored via directional derivative to get the way of finding the extreme of multi function.