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# View of /pkg/man/dsCMatrix-class.Rd

Tue Feb 15 22:09:25 2005 UTC (14 years, 7 months ago) by bates
File size: 3680 byte(s)
Methods and coercions for the dtTMatrix class
\name{dsCMatrix-class}
\docType{class}
\alias{dsCMatrix-class}
\alias{dsTMatrix-class}
\alias{solve,dsCMatrix,matrix-method}
\alias{chol,dsCMatrix,missing-method}
\alias{chol,dsCMatrix,logical-method}
\alias{t,dsCMatrix-method}
\alias{coerce,dsCMatrix,dgTMatrix-method}
\alias{coerce,dsCMatrix,dgeMatrix-method}
\alias{coerce,dsCMatrix,matrix-method}
\alias{determinant,dsCMatrix,missing-method}
\alias{determinant,dsCMatrix,logical-method}
\title{Symmetric, compressed, sparse column matrices}
\description{The \code{dsCMatrix} class is a class of symmetric, sparse
matrices in the compressed, column-oriented format.  In this
implementation the non-zero elements in the columns are sorted into
increasing row order. The \code{dsTMatrix} class is a class of
symmetric, sparse matrices in triplet format.}
\section{Objects from the Class}{
Objects can be created by calls of the form \code{new("dsCMatrix",
...)} or \code{new("dsTMatrix", ...)}
}
\section{Slots}{
\describe{
\item{\code{uplo}:}{A character object indicating if the upper
triangle (\code{"U"} or \code{"u"}) or the lower triangle
(\code{"L"} or \code{"l"}) is stored.  At present only the lower
triangle form is allowed.}
\item{\code{p}:}{Object of class \code{"integer"} of pointers, one
for each column, to the initial (zero-based) index of elements in
the column. (Only present in the \code{dsCMatrix} class.)}
\item{\code{i}:}{Object of class \code{"integer"} of length nnzero
(number of non-zero elements).  These are the row numbers for
each non-zero element in the matrix.}
\item{\code{j}:}{Object of class \code{"integer"} of length nnzero
(number of non-zero elements).  These are the column numbers for
each non-zero element in the matrix. (Only present in the
\code{dsTMatrix} class.)}
\item{\code{x}:}{Object of class \code{"numeric"} - the non-zero
elements of the matrix.}
\item{\code{factors}:}{Object of class \code{"list"} - a list
of factorizations of the matrix. }
\item{\code{Dim}:}{Object of class \code{"integer"} - the dimensions
of the matrix - must be an integer vector with exactly two
non-negative values.}
}
}
\section{Extends}{
Class \code{"dgCMatrix"}, directly.
}
\section{Methods}{
\describe{
\item{solve}{\code{signature(a = "dsCMatrix", b = "matrix")}: Solve
a linear system of equations defined by \code{x} using a Cholesky
decomposition.}
\item{chol}{\code{signature(x = "dsCMatrix", pivot = "logical")}:
Returns (and stores) the Cholesky decomposition of the matrix
\code{x}. If \code{pivot} is \code{TRUE} (the default) Metis is
used to create a reordering of the rows and columns of \code{x} so
as to minimize fill-in.}
\item{determinant}{\code{signature(x = "dsCMatrix", logarithm =
"missing")}: Evaluate the determinant of \code{x} on the
logarithm scale.  This creates and stores the Cholesky factorization.}
\item{determinant}{\code{signature(x = "dsCMatrix", logarithm =
"logical")}: Evaluate the determinant of \code{x} on the
logarithm scale or not, according to the \code{logarithm}
argument.  This creates and stores the Cholesky factorization.}
\item{coerce}{\code{signature(from = "dsCMatrix", to = "dgTMatrix")}}
\item{coerce}{\code{signature(from = "dsCMatrix", to = "dgeMatrix")}}
\item{coerce}{\code{signature(from = "dsCMatrix", to = "matrix")}}
}
}
%\references{}
%\author{}
%\note{}
\seealso{
}
%\examples{}
\keyword{classes}
\keyword{algebra}