摘要: Well, to understand why the covariance matrix of a population is always positive semi-definite, notice that: \[\sum_{i, j=1}^n y_i \cdot y_j \cdot \op 阅读全文
posted @ 2023-12-20 09:21 ChrainY 阅读(2) 评论(0) 推荐(0) 编辑