关于函数的定义
我们决不能让00后大学生学习微积分输在起跑线上，20年后，仍然落后于西方发达国家。
请见本教材第一章第1.2节关于函数的序偶定义：
DEFINITION
A real fimctionof one variable is a set f of ordered pairs of real numbers such that for everyreal number a one of the following two things happens:
(i) There isexactly one real number b for which the ordered pair (a, b) is a member of f.In this case we say that f(a) is defined and we write f(a) = b. The number b iscalled the value of f at a.
(ii) There is noreal number b for which the ordered pair (a, b) is a member of f. In this casewe say that f(a) is undefined.
Thus f(a) = bmeans that the ordered pair (a, b) is an element of f. Here is one way tovisualize a function. Imagine a black box labeled f as in Figure 1.2.1. I（在此省略）
说明：此件系定于7月3日上午向教育部高教司理工处汇报工作之用，
袁萌摘抄于2018年7月1日