tensorSparse: Tensor Product of Sparse Vectors, Matrices or Arrays

In spatstat/spatstat.sparse: Sparse Three-Dimensional Arrays and Linear Algebra Utilities

Tensor Product of Sparse Vectors, Matrices or Arrays

Description

Compute the tensor product of two vectors, matrices or arrays which may be sparse or non-sparse.

Usage

tensorSparse(A, B, alongA = integer(0), alongB = integer(0))

Arguments

A, B	Vectors, matrices, three-dimensional arrays, or objects of class sparseVector, sparseMatrix or sparse3Darray.
alongA	Integer vector specifying the dimensions of A to be collapsed.
alongB	Integer vector specifying the dimensions of B to be collapsed.

Details

This function is a generalisation, to sparse arrays, of the function tensor in the tensor package.

tensorSparse has the same syntax and interpretation as tensor. For example, if A and B are matrices, then tensor(A,B,2,1) is the matrix product A %*% B while tensor(A,B,2,2) is A %*% t(B).

This function tensorSparse handles sparse vectors (class "sparseVector" in the Matrix package), sparse matrices (class "sparseMatrix" in the Matrix package) and sparse three-dimensional arrays (class "sparse3Darray" in the spatstat.sparse package) in addition to the usual vectors, matrices and arrays.

The result is a sparse object if at least one of A and B is sparse. Otherwise, if neither A nor B is sparse, then the result is computed using tensor.

The main limitation is that the result cannot have more than 3 dimensions (because sparse arrays with more than 3 dimensions are not yet supported).

Value

Either a scalar, a vector, a matrix, an array, a sparse vector (class "sparseVector" in the Matrix package), a sparse matrix (class "sparseMatrix" in the Matrix package) or a sparse three-dimensional array (class "sparse3Darray" in the spatstat.sparse package).

Author(s)

\spatstatAuthors

.

See Also

sparse3Darray, aperm.sparse3Darray

Examples

  M <- sparse3Darray(i=1:4, j=sample(1:4, replace=TRUE),
                     k=c(1,2,1,2), x=1:4, dims=c(5,5,2))
  A <- tensorSparse(M, M, 1:2, 2:1)

spatstat/spatstat.sparse documentation built on July 19, 2024, 8:36 p.m.