SpatioTemporal (version 0.9.2)

block.mult: Multiplication of Block Diagonal Matrix and Vector

Description

Computes the matrix product between a block diagonal square matrix and a column vector (or matrix).

Usage

block.mult(mat, X, n.x = dim(X)[2], n.blocks = 1, block.sizes =
           rep(dim(mat)[1]/n.blocks, n.blocks))

Arguments

mat

A block diagonal, square matrix.

X

Vector or matrix to multiply by mat.

n.x

Number of columns in X, defaults correctly if X is a matrix.

n.blocks

Number of diagonal blocks in mat. Defaults to 1 (i.e. a full matrix) if not given.

block.sizes

A vector of length n.blocks with the size of each of the diagonal blocks. If not given it will assume equal-sized blocks.

Value

• Returns mat * X.

encoding

latin1

See Also

Block matrices van be created by make.sigma.B, make.sigma.B.full and make.sigma.nu. Other block matrix functions makeCholBlock, calc.iS.X, calc.tF.times.mat, dot.prod, sumLogDiag. This function is called by loglike.

Examples

#create a matrix
mat <- cbind(c(1,0,0),c(0,2,1),c(0,1,2))
#define the number of blocks and block sizes
block.sizes <- c(1,2)
n.blocks <- length(block.sizes)

#define a X vector
X <- c(1,2,3)

#compute mat \%*\% X
block.mult(mat, X, n.x = 1, n.blocks, block.sizes)
#or the old fashioned way
mat %*% X
if( max(abs(block.mult(mat, X, n.x = 1, n.blocks, block.sizes) -
    (mat %*% X))) > 1e-13 ){
stop("block.mult: Results not equal")
}