这篇文章是盲信号处理，因为是英文文章，所以大家看内容就好了。-Principal component analysis (PCA) is a mainstay of modern data analysis- a black box that

is widely used but poorly understood. The goal of this paper is to dispel the magic behind this

black box. This tutorial focuses on building a solid intuition for how and why principal component

analysis works　furthermore, it crystallizes this knowledge by deriving from simple intuitions, the

mathematics behind PCA . This tutorial does not shy away from explaining the ideas informally,

nor does it shy away from the mathematics. The hope is that by addressing both aspects, readers

of all levels will be able to gain a better understanding of PCA as well as the when, the how and

the why of applying this technique.