pdf(file = "FigLec6.pdf",width=5.5,height=5.5,horiz=T)
#
x <- seq(-1.1,1.1,length=200)
y <- 15*(1-x*x)^2/16
y[abs(x) > 1] <- 0
plot(x=x, y=y, type='l', 
  main="Biweight Kernel", 
  xlab = "bandwidths (h)", ylab = "height")