Convexity of Nonsmooth Functions
Dongyan Chen · Shuxue de shijian yu renshi · 2002
In this paper, we change the directional derivative of function of many variables into the left derivative and the progressive derivative of function of one variable with the help of the definition and the property of function of one variable. The necessary and sufficient condition for the convexity of nonsmooth function of many variables is given and proved by using the criterion of the convexity of function of one variable.