Diagonal {Matrix}  R Documentation 
Create a diagonal matrix object, i.e., an object inheriting from
diagonalMatrix
(or a “standard”
CsparseMatrix
diagonal matrix in cases that is prefered).
Diagonal(n, x = NULL)
.symDiagonal(n, x = rep.int(1,n), uplo = "U", kind)
.trDiagonal(n, x = 1, uplo = "U", unitri=TRUE, kind)
.sparseDiagonal(n, x = 1, uplo = "U",
shape = if(missing(cols)) "t" else "g",
unitri, kind, cols = if(n) 0:(n  1L) else integer(0))
n 
integer specifying the dimension of the (square) matrix. If
missing, 
x 
numeric or logical; if missing, a unit diagonal

uplo 
for 
shape 
string of 1 character, one of 
unitri 
optional logical indicating if a triangular result
should be “unittriangular”, i.e., with 
kind 
string of 1 character, one of 
cols 
integer vector with values from 
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. Analogously,
.triDiagonal
gives a sparse triangularMatrix
.
This can be more efficient than Diagonal(n)
when the result is combined
with further symmetric (sparse) matrices, e.g., in kronecker
,
however not for
matrix multiplications where Diagonal()
is clearly preferred.
.sparseDiagonal()
, the workhorse of .symDiagonal
and
.trDiagonal
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]
.
Martin Maechler
the generic function diag
for extraction
of the diagonal from a matrix works for all “Matrices”.
bandSparse
constructs a banded sparse matrix from
its nonzero sub/super  diagonals. band(A)
returns a
band matrix containing some sub/super  diagonals of A
.
Matrix
for general matrix construction;
further, class diagonalMatrix
.
Diagonal(3)
Diagonal(x = 10^(3:1))
Diagonal(x = (1:4) >= 2)#> "ldiMatrix"
## Use Diagonal() + kronecker() for "repeatedblock" 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 (201210) unitriangular
stopifnot(I4@diag == "U", all(I4 == diag(4)))