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% $Id: pdClasses.Rd,v 1.6 2002/03/05 14:59:39 bates Exp $
\name{pdClasses}
\title{Positive-Definite Matrix Classes}
\alias{pdClasses}
\description{
Standard classes of positive-definite matrices (\code{pdMat})
structures available in the \code{nlme} library.
}
\value{
Available standard classes:
\item{pdSymm}{general positive-definite matrix, with no additional
structure}
\item{pdLogChol}{general positive-definite matrix, with no additional
structure, using a log-Cholesky parameterization}
\item{pdDiag}{diagonal}
\item{pdIdent}{multiple of an identity}
\item{pdCompSymm}{compound symmetry structure (constant diagonal and
constant off-diagonal elements)}
\item{pdBlocked}{block-diagonal matrix, with diagonal blocks of any
"atomic" \code{pdMat} class}
\item{pdNatural}{general positive-definite matrix in natural
parametrization (i.e. parametrized in terms of standard deviations
and correlations). The underlying coefficients are not unrestricted,
so this class should NOT be used for optimization.}
}
\references{
Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models
in S and S-PLUS", Springer.
}
\author{Jose Pinheiro \email{Jose.Pinheiro@pharma.novartis.com} and Douglas Bates \email{bates@stat.wisc.edu}}
\note{
Users may define their own \code{pdMat} classes by specifying a
\code{constructor} function and, at a minimum, methods for the
functions \code{pdConstruct}, \code{pdMatrix} and \code{coef}. For
examples of these functions, see the methods for classes \code{pdSymm}
and \code{pdDiag}.
}
\seealso{\code{\link{pdBlocked}},
\code{\link{pdCompSymm}},
\code{\link{pdDiag}},
\code{\link{pdFactor}},
\code{\link{pdIdent}},
\code{\link{pdMat}},
\code{\link{pdMatrix}},
\code{\link{pdNatural}},
\code{\link{pdSymm}},
\code{\link{pdLogChol}}
}
\keyword{models}
|
