fig819 <- function(post=F)
{
 if(post)
  {#ps.options (colors=ps.colors.rgb[c("blue", "magenta", "cyan",
   #"green", "MediumBlue", "red", "black", "yellow", "blue"),])
    postscript("Fig819.ps", width=4.4, height=6.6, horizontal=F, pointsize=8)
  }
 else {if(dev.cur()==1) motif(); par(ask=T)}
 
 par(mfrow = c(3,2), mar=c(5,3,3,1)+0.1)
 par(mex=0.5,csi=0.11)

 
 SP500 <- matrix(scan("../datasets/SP500",skip=15),ncol=5,byrow=T)
 SP500 <- rev(SP500[1:2529,5])            #closing prices from Jan 2,90
 SP500 <- log(as.numeric(SP500))
 

 ###########  one period return from Jan. 3, 1990   #############
 x <- diff(SP500)^2
 n = length(r1)
 p = 6
 Y <- x[(p+1):n]
 X1 <- x[p:(n-1)]
 X2 <- x[(p-1):(n-2)]
 X3 <- x[(p-2):(n-3)]
 X4 <- x[(p-3):(n-4)]
 X5 <- x[(p-4):(n-5)]
 X6 <- x[(p-5):(n-6)]
 g = 0.75
#fig819.gam   <- gam(Y ~ lo(X1,g) + lo(X2,g)+lo(X3,g) + lo(X4,g)+lo(X5,g)+lo(X6,g))
 r.term  <- predict(fig819.gam, type="term")


 x <- seq(min(x),max(x), length=101)
 plot(x, approx(X1,r.term[,1],x,rule=3)$y, type="l", xlab="(a)", ylab="")
 title("Lag one function")

 plot(x, approx(X2,r.term[,2],x,rule=3)$y, type="l", xlab="(b)", ylab="")
 title("Lag two function")

 plot(x, approx(X3,r.term[,3],x,rule=3)$y, type="l", xlab="(c)", ylab="")
 title("Lag three function")

 plot(x, approx(X4,r.term[,4],x,rule=3)$y, type="l", xlab="(d)", ylab="")
 title("Lag four function")

 plot(x, approx(X5,r.term[,5],x,rule=3)$y, type="l", xlab="(e)", ylab="")
 title("Lag Five function")

 plot(x, approx(X6,r.term[,6],x,rule=3)$y, type="l", xlab="(f)", ylab="")
 title("Lag Six function")




}