statistics-lab_resources-normTail.R

normTail <-
function(m=0, s=1, L=NULL, U=NULL, M=NULL, df=1000, curveColor=1, border=1, col='#569BBD', xlim=NULL, ylim=NULL, xlab='', ylab='', digits=2, axes=1, detail=999, xLab=c('number', 'symbol'), cex.axis=1, xAxisIncr=1, ...){
	if(is.null(xlim)[1]){
		xlim <- m + c(-1,1)*3.5*s
	}
	temp <- diff(range(xlim))
	x    <- seq(xlim[1] - temp/4, xlim[2] + temp/4, length.out=detail)
	y    <- dt((x-m)/s, df)/s
	if(is.null(ylim)[1]){
		ylim <- range(c(0,y))
	}
	plot(x, y, type='l', xlim=xlim, ylim=ylim, xlab=xlab, ylab=ylab, axes=FALSE, col=curveColor, ...)
	if(!is.null(L[1])){
		these <- (x <= L)
		X <- c(x[these][1], x[these], rev(x[these])[1])
		Y <- c(0, y[these], 0)
		polygon(X, Y, border=border, col=col)
	}
	if(!is.null(U[1])){
		these <- (x >= U)
		X <- c(x[these][1], x[these], rev(x[these])[1])
		Y <- c(0, y[these], 0)
		polygon(X, Y, border=border, col=col)
	}
	if(all(!is.null(M[1:2]))){
		these <- (x >= M[1] & x <= M[2])
		X <- c(x[these][1], x[these], rev(x[these])[1])
		Y <- c(0, y[these], 0)
		polygon(X, Y, border=border, col=col)
	}

	if(axes == 1 || axes > 2){
		if(xLab[1]=='symbol'){
			xAt  <- m + (-3:3)*s
			xLab <- expression(mu-3*sigma, mu-2*sigma,
							mu-sigma, mu,	mu+sigma,
							mu+2*sigma, mu+3*sigma)
		} else if(xLab[1] != 'number'){
			stop('Argument "xLab" not recognized.\n')
		} else {
			temp <- seq(xAxisIncr, max(abs(xlim-m))/s, xAxisIncr)*s
			xAt <- m + c(-temp, 0, temp)
			xLab <- round(xAt, digits=digits)
		}
	}
	if(axes > 2){
		axis(1, at=xAt, labels=xLab, cex.axis=cex.axis)
		buildAxis(2, c(y,0), n=3, nMax=3, cex.axis=cex.axis)
	} else if(axes > 1){
		buildAxis(2, c(y,0), n=3, nMax=3, cex.axis=cex.axis)
	} else if(axes > 0){
		axis(1, at=xAt, labels=xLab, cex.axis=cex.axis)
	}

	abline(h=0)
}