n_100
 x_rnorm(n)
 x_sort(x)
# x

 y_c(rep(seq(0,1,1/length(x)),c(rep(2,length(x)+1))))
# y

 x_c(x,x-0.0001)
 x_c(x,min(x)-0.1,max(x)+0.1)
 x_sort(x)
# x

 plot(x,y,type="l",ylab="Empirical density")
 x_seq(min(x),max(x),(max(x)-min(x))/100)
# x
 lines(x,pnorm(x),lty=2)



lines(x,pnorm(x),type="h")





x_seq(-10,15,0.05)
 plot(x,x*dnorm(x,1,1),type="l")
  x_seq(-3,5,0.05)
 plot(x,x*dnorm(x,1,1),type="l")
 lines(x,rep(0,length(x)),type="l")

  
  x_seq(0,6,0.05)
 plot(x,x*dexp(x,1),type="l")
  x_seq(0,10,0.05)
 plot(x,x*dexp(x,1),type="l")
 lines(x,rep(0,length(x)),type="l")
 lines(x,dgamma(x,2,1),lty=3)