说明：  通过matlab代码实现PCA算法程序设计步骤： 包括1、去均值 2、计算协方差矩阵及其特征值和 xtpKUR 特征向量 3、计算协方差矩阵的特征值大于阈值的个数以及 YEzchtH值 4、降序排列特征值，编译通过达到很高的性能。
(PCA algorithm program realization by matlab code design steps include: 1, 2 to the mean, covariance matrix and its eigenvalues and eigenvectors xtpKUR 3, calculate the covariance matrix of eigenvalues greater than the number of threshold values, and only 4 YEzchtH, in descending order eigenvalues, compiled by achieving high performance.)