Kronecker Recurrent Unit (`KRUCell`)

## Paper

https://arxiv.org/abs/1705.10142

## Equations

Replaces the recurrent matrix with a parametrization using the Kronecker product

```math
\begin{equation}
    \mathbf{W} = \mathbf{W}_0 \otimes \cdots \otimes \mathbf{W}_{F-1}
    = \bigotimes_{f=0}^{F-1} \mathbf{W}_f.
\end{equation}
```

## Official implementation

none