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Mon May 9 14:29:12 2005 UTC (14 years, 9 months ago) by bates
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Mon May 9 14:29:12 2005 UTC (14 years, 9 months ago) by bates
File size: 2742 byte(s)
\name{lgCMatrix-class} \docType{class} \alias{lgCMatrix-class} \alias{ltCMatrix-class} \alias{lsCMatrix-class} \alias{\%*\%,lgCMatrix,lgCMatrix-method} \alias{coerce,matrix,lgCMatrix-method} \alias{t,lgCMatrix-method} \title{Compressed, sparse, column-oriented logical matrices} \description{The \code{lgCMatrix} class is a class of general, sparse, logical matrices in the compressed, sparse, column-oriented format. \code{lsCMatrix} and \code{ltCMatrix} are similar classes representing symmetric and triangular matrices respectively. In this implementation the non-zero elements in the columns are sorted into increasing row order. There is no \code{x} slot in this class because the only non-zero value stored is \code{TRUE}.} \section{Objects from the Class}{ Objects can be created by calls of the form \code{new("lgCMatrix", ...)}. } \section{Slots}{ \describe{ \item{\code{uplo}:}{Object of class \code{"character"}. Must be either "U", for upper triangular, and "L", for lower triangular. Present in the triangular and symmetric classes but not in the general class.} \item{\code{diag}:}{Object of class \code{"character"}. Must be either \code{"U"}, for unit triangular (diagonal is all ones), or \code{"N"} for non-unit. The implicit diagonal elements are not explicitly stored when \code{diag} is \code{"U"}. Present in the triangular classes only.} \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.} \item{\code{i}:}{Object of class \code{"integer"} of length nnzero (number of non-zero elements). These are the row numbers for each TRUE element in the matrix. All other elements are FALSE.} \item{\code{Dim}:}{Object of class \code{"integer"} - the dimensions of the matrix.} } } \section{Methods}{ \describe{ \item{coerce}{\code{signature(from = "dgCMatrix", to = "lgCMatrix")}} \item{t}{\code{signature(x = "lgCMatrix")}: returns the transpose of \code{x}} } } %\references{} %\author{} \note{ This class is most frequently used during the symbolic analysis phase of an algorithm involving sparse matrices. Frequently such algorithms involve two phases: a symbolic phase wherein the positions of the non-zeros in the result are determined and a numeric phase wherein the actual results are calculated. During the symbolic phase only the positions of the non-zero elements in any operands are of interest, hence any numeric sparse matrices can be treated as a logical sparse matrices. } \seealso{ \code{\link{dgCMatrix-class}} } %\examples{} \keyword{classes} \keyword{algebra}
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