#####   R-code for making Figure 2.10

	postscript("fig210.ps",width=6,height=6,horizontal=F)

	par(mfrow=c(2,2),mar=c(3,1,1,1))

	x1 <- (seq(1,100)-50)/16
	x  <- (seq(1,100)-50)/20
	y1 <- 1/sqrt(2*pi)*exp(-x^2/2)
	
	plot(x, y1, type="l", lty=1, xaxt="n", yaxt="n", ylim=c(-0.1,0.5),
	     xlab="(a)",ylab="",mgp=c(2,1,0),cex=1, frame.plot=F)
	lines(x1,rep(0,length(x1)),lty=1,lwd=1.5)

	y1 <- (2/sqrt(2*pi)*exp(-(x+0.75)^2/0.5)+2/sqrt(2*pi)*
               exp(-(x-0.75)^2/0.5))/2

	plot(x, y1, type="l", lty=1, xaxt="n", yaxt="n", ylim=c(-0.1,0.5),
	     xlab="(b)",ylab="",mgp=c(2,1,0),cex=1, frame.plot=F)
	lines(x1,rep(0,length(x1)),lty=1,lwd=1.5)

	x  <- seq(1,100)/20
	x1 <- seq(-10,110)/20
	y1 <- 1/(2^1.5*0.5*sqrt(pi))*x^0.5*exp(-x/2)

	plot(x, y1, type="l", lty=1, xaxt="n", yaxt="n", ylim=c(-0.1,0.3),
	     xlab="(c)",ylab="",mgp=c(2,1,0),cex=1, frame.plot=F)
	lines(x1,rep(0,length(x1)),lty=1,lwd=1.5)

	y1 <- 1/(2^1.5*0.5*sqrt(pi))*(5-x)^0.5*exp(-(5-x)/2)

	plot(x[1:99], y1[1:99], type="l", lty=1, xaxt="n", yaxt="n", 
             ylim=c(-0.1,0.3),xlab="(d)",ylab="",mgp=c(2,1,0),cex=1, 
             frame.plot=F)
	lines(x1,rep(0,length(x1)),lty=1,lwd=1.5)


	graphics.off()