## 7.2ߓv͂ƍsxNg
a <- c(3,4)
b <- c(-3,4)
t(a) %*% b       #xNg̓

sqrt(t(a)%*%a)   #mƋ
d <- sqrt(t(a-b)%*%(a-b));d

# ȍsƃxNg
diag(3)
rep(1,3)
diag(0,3,3)
rep(0,3)

## švZ
E <- matrix(1:6,nrow=3,ncol=2)
F <- matrix(0:3,nrow=2,ncol=2)
E%*%F           #s̐
solve(F)@@@@#ts
F%*%(solve(F))  #PʍsɂȂ邩
det(F)@@@@@#s

# UUs߂
(n <- nrow(X))
(Cxx <- (1/n)*t(X)%*%X)

# ֍s߂
S <- diag (sqrt(diag(Cxx)))  #@W΍̑Ίps  
Z <- X %*% solve(S)    #@Wf[^s
R <- (t(Z) %*% Z)/n    #  ֌Ws
