#	October 4, 2005

#	Look at U.S. Airline Data

yr <- seq(1949+1/24,by=1/12,length=96)
airline <- scan("airline.dat")

myplt <- function(log=F,lines=F,xl=c(1949,1957)) {
   if(log) plot(yr,airline,pch=16,log="y",xlim=xl,ylab="Intl Air Traffice")
    else   plot(yr,airline,pch=16,xlim=xl,ylab="International Airline Traffic")
   if(lines) lines(yr,airline)
}

	# fit polynomial model

airtrvl.1 <- function() {
  if(length(dev.list())==1) { my.ps.color() }

  x <- (yr-1949)/12; xx <- seq(0, 2/3,l=351)
  X <- rep(1,96); XX <- rep(1,length(xx))
  myplt(F,T); browser()
  for(k in 1:5) {
    X <- cbind(X,x^k); XX <- cbind(XX,xx^k)
    ab <- lsfit(X,airline,int=F)$coef; yh <- c( XX %*% ab )
    myplt(F); lines(12*xx+1949,yh,lwd=2,col=3)
    title(paste("polynomial order ",k))
    print(" use ps.copy and mv to poly1.eps ")
    browser()
  }
}

airtrvl.1()

airtrvl.2 <- function() {
  if(length(dev.list())==1) { my.ps.color() }

  x <- (yr-1949)/12; xx <- seq(0, 2/3,l=351)
  X <- rep(1,96); XX <- rep(1,length(xx))
  myplt(T,T); browser()
  for(k in 1:5) {
    X <- cbind(X,x^k); XX <- cbind(XX,xx^k)
    ab <- lsfit(X,log(airline),int=F)$coef; yh <- exp(c( XX %*% ab ))
    myplt(T); lines(12*xx+1949,yh,lwd=2,col=3)
    title(paste("polynomial order ",k))
    print(" use ps.copy and mv to poly1.eps ")
    browser()
  }
}

airtrvl.2()