Matrix (version 0.999375-8)

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")

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

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.

See Also

the generic function diag for extraction of the diagonal from a matrix works for all Matrices. Matrix, 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"))