现行的不少教材在叙述凸函数定义时,通常都假设函数是连续的.本文以没有连续为前提的一元凸函数的定义为基础,探讨了函数的连续性,左右导数的存在性,凸函数在区间端点的形态,最后利用左右导数,给出了判定函数为凸的一个充条件.
The convex function often plays an important role in many fields of mathematics. It is meaningful to study the analytical properties of the convex function. In these paper, the continuity of the convex function has been studied. The limit property of the convex function about the end points of the interval has been discussed. A criteria of convex function has been given.