“函数”是数学中一个重要而又最基本的概念,自从笛卡尔引入变数以后,变量和函数等概念就日益渗透到数学的各个分支领域中.在数学的发展历程中,函数的概念不断拓广、函数的定义不断演变,形成具有代表性的三种说法,即变量说、对应说(映射说)与关系说,它们各有利弊. Since the introduction of variables by Descartes, concepts such as variables and functions have increasingly penetrated into all branches of mathematics.In the course of the development of mathematics, the notion of function Continuously expanding, the definition of the function evolves continuously to form three representative representations. That is to say, the variables say that they have their advantages and disadvantages according to the relation (say) and the relation.