kernel.factor.Rd
\name{kernel.factor}
\alias{kernel.factor}
\title{Scale factor for density kernel}
\description{
Returns a scale factor for the kernels used in density estimation
for numerical data.
}
\usage{
kernel.factor(kernel = "gaussian")
}
\arguments{
\item{kernel}{
String name of the kernel.
Options are
\code{"gaussian"}, \code{"rectangular"},
\code{"triangular"},
\code{"epanechnikov"},
\code{"biweight"},
\code{"cosine"} and \code{"optcosine"}.
(Partial matching is used).
}
}
\details{
Kernel estimation of a probability density in one dimension
is performed by \code{\link[stats]{density.default}}
using a kernel function selected from the list above.
This function computes a scale constant for the kernel.
For the Gaussian kernel, this constant is equal to 1.
Otherwise, the constant \eqn{c} is such that the kernel
with standard deviation \eqn{1} is supported on the interval
\eqn{[-c,c]}.
For more information about these kernels,
see \code{\link[stats]{density.default}}.
}
\value{
A single number.
}
\seealso{
\code{\link[stats]{density.default}},
\code{\link{dkernel}},
\code{\link{kernel.moment}},
\code{\link{kernel.squint}}
}
\examples{
kernel.factor("rect")
# bandwidth for Epanechnikov kernel with half-width h=1
h <- 1
bw <- h/kernel.factor("epa")
}
\author{\adrian
and Martin Hazelton
}
\keyword{methods}
\keyword{nonparametric}
\keyword{smooth}