Kronecker product

A Kronecker product is simply a tensor product whose underlying vector space basis is relabeled. In the present context this is realized by combining multiple index labels into one. The associated dimension to the new label is then simply the product of the dimensions associated to the old index labels respectively.

Usage

kron(x, ...)

Arguments

x

A labeled tensor object, created by %_% or tensor().

...

Any number of expressions (separated by a comma) of the form .(<label1>, <label2>, ..., <labeln-1>) -> <labeln+1>.

Value

A modified tensor object.

See also

Wikipedia: Kronecker Product

Other tensor operations: Ops.tensor(), asym(), l(), r(), subst(), sym()

Examples

a <- array(1:8, dim = c(2, 2, 2))
a %_% .(i, j, k) |> kron(.(i, j) -> l)
#> <Labeled Array> [4x2] .(-l, -k)
#>      [,1] [,2]
#> [1,]    1    5
#> [2,]    2    6
#> [3,]    3    7
#> [4,]    4    8