crs (version 0.15-33)

# tensor.prod.model.matrix: Utility functions for constructing tensor product smooths

## Description

Produce model matrices or penalty matrices for a tensor product smooth from the model matrices or penalty matrices for the marginal bases of the smooth.

## Usage

`tensor.prod.model.matrix(X)`

## Arguments

X

a list of model matrices for the marginal bases of a smooth

## Value

Either a single model matrix for a tensor product smooth, or a list of penalty terms for a tensor product smooth.

## Details

If `X[[1]]`, `X[[2]]` ... `X[[m]]` are the model matrices of the marginal bases of a tensor product smooth then the ith row of the model matrix for the whole tensor product smooth is given by `X[[1]][i,]%x%X[[2]][i,]%x% ... X[[m]][i,]`, where `%x%` is the Kronecker product. Of course the routine operates column-wise, not row-wise!

## References

Wood, S.N. (2006) “Low Rank Scale Invariant Tensor Product Smooths for Generalized Additive Mixed Models”. Biometrics 62(4):1025-1036

`te`, `smooth.construct.tensor.smooth.spec`
```# NOT RUN {