in favour of `fmesher::fm_row_kron()`

.

Takes two Matrices and computes the row-wise Kronecker product. Optionally applies row-wise weights and/or applies an additional 0/1 row-wise Kronecker matrix product.

## Arguments

- M1
A matrix that can be transformed into a sparse Matrix.

- M2
A matrix that can be transformed into a sparse Matrix.

- repl
An optional index vector. For each entry, specifies which replicate the row belongs to, in the sense used in

`INLA::inla.spde.make.A`

- n.repl
The maximum replicate index, in the sense used in

`INLA::inla.spde.make.A()`

.- weights
Optional scaling weights to be applied row-wise to the resulting matrix.

## Value

A `Matrix::sparseMatrix`

object.

## Author

Finn Lindgren finn.lindgren@gmail.com