my_rmvnorm2<- function(mu = rep(0,ncol(sigma)), sigma = matrix(0,2,2),n)
{
  m<-ncol(sigma)
A<- matrix(nrow=m, ncol= n)
dec<- svd(sigma)
for(i in 1:n){
  A[,i]<- dec$u %*% (rnorm(m)*sqrt(dec$d))+ mu
  }
return(t(A))
}
my_rmvnorm2(sigma= matrix(c(2,0.1,0.1,1),ncol=2),n=1000)
plot(my_rmvnorm2(sigma= matrix(c(2,0.1,0.1,1),ncol=2),n=1000))