LKDiag {LatticeKrig}

Create a matrix with given entries on the given diagonals

Description

This function builds a matrix in which each entry on a given diagonal has the same value. The matrix can be any size, not necessarily square, and the user can specify arbitrary diagonals to fill. If ncol is not set, the output will be a square matrix. If diags is not set, the entries will be placed as close as possible to the main diagonal; e.g. passing in one value for entries will produce a diagonal matrix, and passing in a vector of 3 values will produce a tridiagonal matrix. If an even number of entries are provided, they will be placed symmetrically around the main diagonal, leaving the main diagonal as zeroes.

Usage

LKDiag(entries, nrow, diags = NULL, ncol = nrow,
full = FALSE)

Arguments

entries

The values to put on each diagonal.

nrow

The number of rows in the matrix; if ncol isn't set, the matrix will be square with nrow rows and columns.

diags

The diagonals to put the entries on. 0 corresponds to the main diagonal, positive values go above the main diagonal, and negatives go below.

ncol

The number of columns in the matrix, if it's different from the number of rows.

full

If TRUE return a dense matrix in the usual R matrix format. If FALSE return a sparse matrix in spam format.

Value

LKDiag returns a (dense) matrix with the given diagonals.

Author(s)

Matt Iverson

Examples

#produces a 5x5 identity matrix
LKDiag(1, 5)

#produces a 6x6 tridiagonal matrix
LKDiag(c(1, -2, 1), 6)
LKDiag(c(1, -2, 1), 6, diags=(-1:1))

#produces a 5x5 matrix with 3 on the main diagonal and the corners
n <- 5
LKDiag(3, n, diags=c(0, n-1, -(n-1)))

# each of the following produces a 4x6 matrix with a 2 in the diagonal 
# below the main diagonal and 5 in the diagonal  above it
LKDiag(c(2, 5), nrow = 4, ncol = 6)
LKDiag(c(2, 5), nrow = 4, ncol = 6, diags = c(-1, 1))
LKDiag(c(5, 2), nrow = 4, ncol = 6, diags = c(1, -1))