说明：  除了理论上的作用,主要是为了更好的存储数据和计算.计算机存储数据存的就是一个矩阵,如果一个矩阵能奇异值分析,那么存的数据就很少,而且计算也很方便
(In addition to the role of theory, the main purpose is to better store data and calculation. Computer storage data is a matrix, if a matrix can singular value analysis, then there is little data, and the calculation is very convenient)