Triangular, (compressed) sparse column matrices

Description

The "dtCMatrix" class is a class of triangular, 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 "dtTMatrix" class is a class of triangular, sparse matrices in triplet format.

Objects from the Class

Objects can be created by calls of the form new("dtCMatrix", ...) or calls of the form new("dtTMatrix", ...), but more typically automatically via Matrix() or coercion such as as(x, "dtCMatrix").

Slots

uplo:

Object of class "character". Must be either "U", for upper triangular, and "L", for lower triangular.

diag:

Object of class "character". Must be either "U", for unit triangular (diagonal is all ones), or "N"; see triangularMatrix.

p:

Object of class "integer" of pointers, one for each column, to the initial (zero-based) index of elements in the column. (Only present in the dtCMatrix class.)

i:

Object of class "integer" of length nnzero (number of non-zero elements). These are the row numbers for each non-zero element in the matrix.

j:

Object of class "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 dtTMatrix class.)

x:

Object of class "numeric" - the non-zero elements of the matrix.

Dim,Dimnames:

The dimension (a length-2 "integer") and corresponding names (or NULL), inherited from the Matrix, see there.

Extends

Class "dgCMatrix", directly. Class "triangularMatrix", directly. Class "dMatrix", "sparseMatrix", and more by class "dgCMatrix" etc, see the examples.

Methods

coerce

signature(from = "dtCMatrix", to = "dgTMatrix")

coerce

signature(from = "dtCMatrix", to = "dgeMatrix")

coerce

signature(from = "dtTMatrix", to = "dgeMatrix")

coerce

signature(from = "dtTMatrix", to = "dtrMatrix")

coerce

signature(from = "dtTMatrix", to = "matrix")

solve

signature(a = "dtCMatrix", b = "matrix")

solve

signature(a = "dtCMatrix", b = "dgeMatrix")

solve

signature(a = "dtCMatrix", b = "missing")

solve

signature(a = "dtCMatrix", b = "numeric")

solve

signature(a = "dtCMatrix", b = "CsparseMatrix"): fully sparse triangular solve, in traditional S/R aka backsolve.

t

signature(x = "dtCMatrix"): returns the transpose of x

t

signature(x = "dtTMatrix"): returns the transpose of x

See Also

Classes dgCMatrix, dgTMatrix, dgeMatrix, and dtrMatrix.

Examples

showClass("dtCMatrix")

showClass("dtTMatrix")
t1 <- new("dtTMatrix", x= c(3,7), i= 0:1, j=3:2, Dim= as.integer(c(4,4)))
t1
## from  0-diagonal to unit-diagonal {low-level step}:
tu <- t1 ; tu@diag <- "U"
tu
(cu <- as(tu, "dtCMatrix"))
str(cu)# only two entries in @i and @x
stopifnot(cu@i == 1:0,
          all(2 * symmpart(cu) == Diagonal(4) + forceSymmetric(cu)))

t1[1,2:3] <- -1:-2
diag(t1) <- 10*c(1:2,3:2)
t1 # still triangular
(it1 <- solve(t1))
t1. <- solve(it1)
all(abs(t1 - t1.) < 10 * .Machine$double.eps)