中文说明： PCA的基本思想是将原来的指标重新组合成一组新的相互无关的几个综合指标来代替原来的指标。同时根据实际需要，从中可取几个较少的综合指标作为代表原来变量的总体性指标，尽可能多地反映原来的指标信息，达到降维的目的。 此程序在matlab环境下以PCA为基础进行了图像压缩和人脸识别两种算法的设计。
English Description：
The basic idea of PCA is to recombine the original indexes into a group of new independent comprehensive indexes to replace the original indexes. At the same time, according to the actual needs, a few less comprehensive indicators can be selected as the overall indicators representing the original variables, so as to reflect the original index information as much as possible, so as to achieve the purpose of dimension reduction.