As a mathematical reference book, what characteristics does this giant manual require? In the process of writing, the person in charge of the publishing house and we reached a consensus that the manual should be scientific, advanced, practical, standardized and concise. More than 200 authors and reviewers have made efforts according to these characteristics and requirements, and we would like to thank them for their full cooperation and efforts, so that the manual basically reflects the above-mentioned expected characteristics or characteristics. This series is a key publishing project of the ninth five-year plan. For the convenience of readers, this manual is published in five volumes, which are called classic mathematics volume, modern mathematics volume, computer mathematics volume, random mathematics volume and economic mathematics volume respectively. It should be pointed out that the ownership of each volume (title) is relative, and the balance of each volume is considered here. For example, the article "Monte Carlo Method" can also be classified as "Computer Mathematics Volume".