Covariance matrix

• Statistical simulation of the Covariance matrix with R-Project
  

  > x1<- c(rep(15,4),rep(20,3),rep(25,1),rep(15,1),rep(20,4),rep(25,7));
  > y1<- c(rep(5,4),rep(5,3),rep(5,1),rep(10,1),rep(10,4),rep(10,7));
  > x2<- (x1-15)/5;
  > y2<- (y1-5)/5;
  > ni<- table(x1);
  > n<-sum(ni);
  > xt1<-cbind(x1,y1);
  > xt2<-cbind(x2,y2);
  > cov(xt1)*(n-1)/n
          x1   y1
  x1 15.6875 5.25
  y1  5.2500 6.00
  
  > cov(xt2)*(n-1)/n
         x2   y2
  x2 0.6275 0.21
  y2 0.2100 0.24