Matrix (version 1.0-4)

Diagonal: Create Diagonal Matrix Object

Description

Create a diagonal matrix object, i.e., an object inheriting from diagonalMatrix.

Usage

Diagonal(n, x = NULL)
.symDiagonal(n, x = rep.int(1,n), uplo = "U")
.sparseDiagonal(n, x = rep.int(1,m), uplo = "U",
                shape = if(missing(cols)) "t" else "g",
	        kind, cols = if(n) 0:(n - 1L) else integer(0))

Arguments

n

integer specifying the dimension of the (square) matrix. If missing, length(x) is used.

x

numeric or logical; if missing, a unit diagonal $n \times n$ matrix is created.

uplo

for .symDiagonal, the resulting sparse symmetricMatrix will have slot uplo set from this argument, either "U" or "L". Only rarely will it make sense t

shape

string of 1 character, one of c("t","s","g"), to chose a triangular, symmetric or general result matrix.

kind

string of 1 character, one of c("d","l","n"), to chose the storage mode of the result, from classes dsparseMatrix, lsparseMatrix, or

cols

integer vector with values from 0:(n-1), denoting the columns to subselect conceptually, i.e., get the equivalent of Diagonal(n,*)[, cols + 1].

Value

• Diagonal() returns an object of class ddiMatrix or ldiMatrix (with superclass diagonalMatrix).

  .symDiagonal() returns an object of class dsCMatrix or lsCMatrix, i.e., a sparse symmetric matrix. This can be more efficient than Diagonal(n) when the result is combined with further symmetric (sparse) matrices, however not for matrix multiplications where Diagonal() is clearly preferred.

  .sparseDiagonal(), the workhorse of .symDiagonal returns a CsparseMatrix (the resulting class depending on shape and kind) representation of Diagonal(n), or, when cols are specified, of Diagonal(n)[, cols+1].

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

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"))