Matrix (version 1.7-4)

Diagonal: Construct a Diagonal Matrix

Description

Construct a formally diagonal Matrix, i.e., an object inheriting from virtual class diagonalMatrix (or, if desired, a mathematically diagonal CsparseMatrix).

Usage

Diagonal(n, x = NULL, names = FALSE)
.sparseDiagonal(n, x = NULL, uplo = "U", shape = "t", unitri = TRUE, kind, cols)
    .trDiagonal(n, x = NULL, uplo = "U", unitri = TRUE, kind)
   .symDiagonal(n, x = NULL, uplo = "U", kind)

Value

Diagonal() returns an object inheriting from virtual class

diagonalMatrix.

.sparseDiagonal() returns a CsparseMatrix

representation of Diagonal(n, x) or, if cols is given, of Diagonal(n, x)[, cols+1]. The precise class of the result depends on shape and kind.

.trDiagonal() and .symDiagonal() are simple wrappers, for .sparseDiagonal(shape = "t") and

.sparseDiagonal(shape = "s"), respectively.

.sparseDiagonal() exists primarily to leverage efficient C-level methods available for CsparseMatrix.

See Also

the generic function diag for extraction of the diagonal from a matrix works for all “Matrices”.

bandSparse constructs a banded sparse matrix from its non-zero sub-/super - diagonals. band(A) returns a band matrix containing some sub-/super - diagonals of A.

Matrix for general matrix construction; further, class diagonalMatrix.

Examples

 
library(stats, pos = "package:base", verbose = FALSE)

Diagonal(3)
Diagonal(x = 10^(3:1))
Diagonal(x = (1:4) >= 2)#-> "ldiMatrix"

## Use Diagonal() + kronecker() for "repeated-block" matrices:
M1 <- Matrix(0+0:5, 2,3)
(M <- kronecker(Diagonal(3), M1))

(S <- crossprod(Matrix(rbinom(60, size=1, prob=0.1), 10,6)))
(SI <- S + 10*.symDiagonal(6)) # sparse symmetric still
stopifnot(is(SI, "dsCMatrix"))
(I4 <- .sparseDiagonal(4, shape="t"))# now (2012-10) unitriangular
stopifnot(I4@diag == "U", all(I4 == diag(4)))

  L <- Diagonal(5, TRUE)
  stopifnot(L@diag == "U", identical(L, Diagonal(5) > 0))