Function to get the precision matrix of an `inla_rspde`

object created with the `rspde.matern()`

function.

## Usage

```
# S3 method for inla_rspde
precision(object, theta = NULL, ...)
```

## Arguments

- object
The

`inla_rspde`

object obtained with the`rspde.matern()`

function.- theta
If null, the starting values for theta will be used. Otherwise, it must be suplied as a vector. For stationary models, we have

`theta = c(log(tau), log(kappa), nu)`

. For nonstationary models, we have`theta = c(theta_1, theta_2, ..., theta_n, nu)`

.- ...
Currently not used.