#####   R-code for making Figure 2.1

	x  <- (seq(1,100)-50)/15
	y1 <- pnorm(x)
	y2 <- (exp(-x^2/2))/sqrt(2*pi)

	postscript("fig21.ps",width=7.5,height=4,horizontal=F)

	par(mfrow=c(1,2), mar=c(4,4,1,1))

	plot(x,y1,type="l",xlab="x",ylab=expression(Phi(x)),
             xaxt="n",yaxt="n",mgp=c(2,1,0),cex=1)
	axis(2,at=c(0,0.25,0.5,0.75,1),labels=c("0","0.25",
             "0.5","0.75","1"),cex=1)
	axis(1,at=c(-2,-1,0,1,2),labels=c("-2","-1","0","1","2"),cex=1)
	title(xlab="(a)")
	
	plot(x,y2,type="l",xlab="x",ylab=expression(phi(x)),xaxt="n",
	     mgp=c(2,1,0),cex=1)
	axis(1,at=c(-2,-1,0,1,2),labels=c("-2","-1","0","1","2"),cex=1)
	title(xlab="(b)")

	graphics.off()