Tensor decomposition


In multilinear algebra, a tensor decomposition is any scheme for expressing a "data tensor" as a sequence of elementary operations acting on other, often simpler tensors. Many tensor decompositions generalize some matrix decompositions.
Tensors are generalizations of matrices to higher dimensions and can consequently be treated as multidimensional fields.
The main tensor decompositions are:

Notation

This section introduces basic notations and operations that are widely used in the field.
SymbolsDefinition
scalar, vector, row, matrix, tensor
vectorizing either a matrix or a tensor
matrixized tensor
mode-m product

Introduction

A multi-way graph with K perspectives is a collection of K matrices with dimensions I × J. This collection of matrices is naturally represented as a tensor X of size I × J × K. In order to avoid overloading the term “dimension”, we call an I × J × K tensor a three “mode” tensor, where “modes” are the numbers of indices used to index the tensor.