# Blog

## 小仙女的七夕

heart1 = function(name) { t = seq(0, 60, len = 100) plot(c(-8, 8), c(0, 20), type = "n", axes = FALSE, xlab = "", ylab = "") x = -0.01 * (-t^2 + 40 * t + 1200) * sin(pi * t/180) y = 0.01 * (-t^2 + 40 * t + 1200) * cos(pi * t/180) lines(x, y, lwd = 4) lines(-x, y, lwd = 4) text(0, 7, &

## 用陶哲轩公式求解特征向量

Tao’s equation aims to get the eigenvectors from Hemi-matrix from the eigenvalues of the matrix as well as the sub matrix. This could allow to calculate the eigenvectors to be easy and more flexible. Results R code (Simple one) set.seed(1992) dat = mvtnorm::rmvnorm(100,sigma = diag(10)) dat.std = scale(dat) # get variance-covariance matrix A = cov(dat.std) lam_A = eigen(A)\$values n = nrow(A) res = rep(1, n) for

## LDA vs. QDA vs. Logistic Regression

1. Classification Model比较 . LDA QDA Logistic KNN Parameters Less More Less Non-parametric Decision. Linear Quatratic Linear Non-linear Bias High Low High Low 对于两个Linear Decision Boundary的方法而言(LDA & Logistic regression)

## 鲜花广场和摇滚乐

Washinton St.和Dubuque St.交叉口的对面是一段狭长的鲜花广场，此时正盛放着兰花。广场尽头是联合酒吧，周五晚上乐队就在那儿弹奏摇滚乐。高昂的