Machine learning PCA

 http://www.cs.otago.ac.nz/cosc453/student_tutorials/principal_components.pdf

https://chih-sheng-huang821.medium.com/%E6%A9%9F%E5%99%A8-%E7%B5%B1%E8%A8%88%E5%AD%B8%E7%BF%92-%E4%B8%BB%E6%88%90%E5%88%86%E5%88%86%E6%9E%90-principle-component-analysis-pca-58229cd26e71