lowess <- function(x, y=NULL, f=2/3, iter=3, delta=.01*diff(range(xy$x[o]))) {
	xy <- xy.coords(x,y)
	if(length(xy$x) != length(xy$y)) stop("x and y lengths differ")
	n <- length(xy$x)
	o <- order(xy$x)
	.C("lowess",
		x=as.double(xy$x[o]),
		as.double(xy$y[o]),
		n,
		as.double(f),
		as.integer(iter),
		as.double(delta),
		y=double(n),
		double(n),
		double(n))[c("x","y")]
}
