The Kronecker product is named after the German mathematician Leopold Kronecker (1823–1891), even though there is little evidence that he was the first to define and use it. The Kronecker product is also sometimes called matrix direct product. The Kronecker product is to be distinguished from the usual matrix multiplication, which is an entirely different operation. It is a specialization of the tensor product (which is denoted by the same symbol) from vectors to matrices and gives the matrix of the tensor product linear map with respect to a standard choice of basis. In mathematics, the Kronecker product, sometimes denoted by ⊗, is an operation on two matrices of arbitrary size resulting in a block matrix.
For the Kronecker product of representations of symmetric groups, see Kronecker coefficient.
