Fig2.2 <- function()
{
#  postscript(file = "Fig2.2.ps", horiz = F, height = 6.5, width = 6.5)
  par(mfrow = c(2, 2), mar = c(1.5, 1.5, 1.5, 0.5), mgp = c(5, 0.4, 0))
  x <- seq(-2, 2, length = 200)
  plot(x, dnorm(x), type = "l")
  mtext("Gaussian kernel", side = 3, line = 0.1)
  x <- seq(-1, 1, length = 200)
  plot(x, 1 - abs(x), type = "l")
  mtext("Triangle kernel", side = 3, line = 0.1)
  plot(x, (3 * (1 - x^2))/4, type = "l")
  mtext("Epanechnikov kernel", side = 3, line = 0.1)
  plot(x, (15 * (1 - x^2)^2)/16, type = "l")
  mtext("Biweight kernel", side = 3, line = 0.1)
#  graphics.off()
 NULL
}