Summary: Convergence is an important tool to study functions, which means to converge to a point and approach a certain value. The types of convergence are convergence sequence, functional convergence, global convergence and local convergence. Convergence of large numbers means that functions have limits.

Function convergence criterion: the definition that a function converges to a certain point. For any real number C, there is a number greater than 0, and for any two numbers A and B, the definition that A minus B is greater than 0 and less than C .. converges well reflects the essence of mathematical analysis.

Said:

First of all, we should understand that a function is the corresponding relationship between sets. Then, we should understand that there is more than one functional relationship between A and B, and finally, we should focus on understanding the three elements of the function.

The corresponding rules of functions are usually expressed by analytical expressions, but a large number of functional relationships can not be expressed by analytical expressions, but only by images, tables and other forms.