\name{prepanel.functions}
\alias{prepanel.lmline}
\alias{prepanel.loess}
\alias{prepanel.qqmathline}
\title{ Useful Prepanel Function for Lattice}
\description{
  These are predefined prepanel functions available in Lattice.
}
\synopsis{
prepanel.loess(x, y, span, degree, family, evaluation, lwd, lty,
               col, ...)
}
\usage{
prepanel.lmline(x, y, ...)
prepanel.loess(x, y, ...)
prepanel.qqmathline(y, distribution, f.value = ppoints, ...) 
}
\arguments{
  \item{x, y}{x and y values.}
  \item{distribution}{ quantile function for theoretical distribution}
  \item{f.value}{ as used in \code{qqmath}}
  \item{\dots}{other arguments}
}
\value{
  usually a list with components \code{xlim, ylim, dx, dy}, the first
  two being used to calculate panel axes limits, the last two for
  banking computations. There are also several undocumented prepanel
  functions that serve as the default for high level functions, e.g.,
  \code{prepanel.default.xyplot} 
}
\seealso{\code{\link{trellis.par.get}}, \code{\link{Lattice}}. See
  \code{\link[modreg]{loess.smooth}} for further options to
  \code{prepanel.loess}
}
\author{ Deepayan Sarkar\email{deepayan@stat.wisc.edu}}
\keyword{dplot}