\name{expand}
\title{Expand a Decomposition into Factors}
\usage{
expand(x, \dots)
}
\alias{expand}
\alias{expand.default}
\description{
    Expands decompositions stored in compact form into factors.
}
\arguments{
    \item{x}{
	a matrix decomposition. 
    }
    \item{...}{
	the method for \code{"qr.Matrix"} has an additional argument.
    }
}
\value{
    the expanded decomposition.
}
\details{
    This is a generic function with special methods for different types
    of decompositions.
    Use \code{\link{methods}("expand")} to list all the methods for the
    \code{expand} generic.
}
\section{NOTE}{
    Factors for decompositions such as \code{lu} and \code{qr} can be
    stored in a compact form.
    The function \code{expand} allows all factors to be fully expanded. 
}
\seealso{
%    \code{\link{expand.lu.Matrix}}, \code{\link{expand.lu.Hermitian}},
%    \code{\link{expand.qr.Matrix}}, \code{\link{expand.eigen.Matrix}},
    \code{\link{facmul}}.
}
\examples{
library(Matrix)
x <- Matrix( 1:9, 3, 3)
expand(qr(x))
}
\keyword{algebra}