Calculation method, also known as numerical mathematics, is a subject that studies numerical solutions of algebra, differential method, functional analysis, statistical mathematics and other problems. And the numerical function should refer to the function belonging to this discipline. People understand it more as transforming abstract functional relationships into corresponding numerical relationships, that is, digitizing various functions, that is, making various numerical tables, such as trigonometric function tables, which is called numerical functions. Nowadays, with the popularization of computer application, many computer calculation methods involve a variety of numerical functions.