# What is kronecker product?

**Asked by: Mr. Edmond Rosenbaum**

Score: 4.2/5 (36 votes)

In mathematics, the Kronecker product, sometimes denoted by ⊗, is an operation on two matrices of arbitrary size resulting in a block matrix. It is a generalization of the outer product from vectors to matrices, and gives the matrix of the tensor product linear map with respect to a standard choice of basis.

View full answerLikewise, people ask, What is Kronecker product used for?

The Kronecker product is an

**operation that transforms two matrices into a larger matrix that contains all the possible products of the entries of the two matrices**. It possesses several properties that are often used to solve difficult problems in linear algebra and its applications.

Likewise, Is Kronecker product same as tensor product?. Sometimes the Kronecker product is also called

**direct product**or tensor product.

Also to know, Is the Kronecker product associative?

KRON 4 (4.2. 6 in [9]) The Kronecker product is

**associative**, i.e. (A ⊗ B)

How do you calculate tensor product?

We start by defining the tensor product of two vectors. Definition 7.1 (Tensor product of vectors). If x, y are vectors of length M and N, respectively, their tensor product x⊗y is defined as the M ×N-matrix defined by (x ⊗ y)ij = xiyj. In other words,

**x ⊗ y = xyT**.

**16 related questions found**

### Is tensor product commutative?

The tensor product is linear in both factors. ... Contrary to the common multiplication it **is not necessarily commutative** as each factor corresponds to an element of different vector spaces.

### How do you contract a tensor?

The contraction of a single mixed tensor occurs when a pair of literal indices (one a subscript, the other a superscript) **of the tensor are set equal to each other and summed over**. In the Einstein notation this summation is built into the notation. The result is another tensor with order reduced by 2.

### What are tensor operations?

Tensors are **a type of data structure used in linear algebra**, and like vectors and matrices, you can calculate arithmetic operations with tensors. ... That tensors are a generalization of matrices and are represented using n-dimensional arrays.

### What is the difference between tensor and matrix?

In a defined system, a matrix is just a container for entries and it doesn't change if any change occurs in the system, whereas a tensor is an entity in the system that interacts with other entities in a system and **changes its values when other values change**.

### What is the inner product of a matrix?

If the dimensions are the same, then the inner product is **the trace of the outer product** (trace only being properly defined for square matrices). In an informal summary: "inner is horizontal times vertical and shrinks down, outer is vertical times horizontal and expands out".

### What is Atensor?

In mathematics, a tensor is **an algebraic object that describes a multilinear relationship between sets of algebraic objects related to a vector space**. Objects that tensors may map between include vectors and scalars, and even other tensors. ... This leads to the concept of a tensor field.

### What is the meaning of trace of matrix?

The trace of a matrix is **the sum of the diagonal elements of the matrix**: (13.49) The trace is sometimes called the spur, from the German word Spur, which means track or trace. For example, the trace of the n by n identity matrix is equal to n.

### Is the tensor product linear?

Product of tensors

is **the dual vector space** (which consists of all linear maps f from V to the ground field K).

### How do you write a tensor product in latex?

The tensor product : V ⊗ W **(Latex: V \otimes W )** .

### What is Kron Matlab?

K = kron( A,B ) **returns the Kronecker tensor product of matrices A and B** . If A is an m -by- n matrix and B is a p -by- q matrix, then kron(A,B) is an m*p -by- n*q matrix formed by taking all possible products between the elements of A and the matrix B .

### What is tensor example?

A tensor field has a tensor corresponding to each point space. An example is **the stress on a material, such as a construction beam in a bridge**. Other examples of tensors include the strain tensor, the conductivity tensor, and the inertia tensor.

### What are the different types of tensors?

**There are four main tensor type you can create:**

- Variable.
- constant.
- placeholder.
- SparseTensor.

### Why stress is a tensor?

Stress has both magnitude and direction but it does not follow the vector law of addition thus, it is not a vector quantity. Instead, **stress follows the coordinate transformation law of addition**, and hence, stress is considered as a tensor quantity. ... Therefore, stress is a tensor quantity, and (C) is the correct option.

### What is the product of two tensors?

If the two vectors have dimensions n and m, then their outer product is an **n × m matrix**. More generally, given two tensors (multidimensional arrays of numbers), their outer product is a tensor. The outer product of tensors is also referred to as their tensor product, and can be used to define the tensor algebra.

### What does it mean to contract a tensor?

To contract a tensor is **to set two of the indices equal and sum over them**, so given a tensor Aij the contraction is A=Aii=A11+A22+A33+A44 The Bianchi identities you list have five indices. To contract them, you would set some pair equal and sum over them.

### What is the cross product of two vectors?

The cross product of two vectors is **the third vector that is perpendicular to the two original vectors**. Its magnitude is given by the area of the parallelogram between them and its direction can be determined by the right-hand thumb rule.

### Is direct product commutative?

The direct product is **commutative and associative up to isomorphism**. That is, G × H ≅ H × G and (G × H) × K ≅ G × (H × K) for any groups G, H, and K. The order of a direct product G × H is the product of the orders of G and H: ... This follows from the formula for the cardinality of the cartesian product of sets.

### Are tensors associative?

The binary tensor product is **associative**: (M_{1} ⊗ M_{2}) ⊗ M_{3} is naturally isomorphic to M_{1} ⊗ (M_{2} ⊗ M_{3}). The tensor product of three modules defined by the universal property of trilinear maps is isomorphic to both of these iterated tensor products.

### What is the difference between Cartesian product and tensor product?

The difference between Cartesian and Tensor product of two vector spaces is that **the elements of the cartesian product are vectors and in the tensor product are linear applications (mappings)**, this last are vectors as well but these ones applied onto elements of V1×V2 gives a K−number.