The model formula will be handled using `stats::model.matrix()`

, and so
the the same approach to include interactions in `stats::lm()`

applies when
specifying the `formula`

. In addition to `stats::lm()`

, it is possible to
include `common_xregs`

in the model formula, such as `trend()`

, `season()`

,
and `fourier()`

.

## Specials

### xreg

Exogenous regressors can be included in a LOGISTIC model without explicitly
using the `xreg()`

special. Common exogenous regressor specials as specified
in `common_xregs`

can also be used. These regressors are handled using
`stats::model.frame()`

, and so interactions and other functionality behaves
similarly to `stats::lm()`

.

```
xreg(...)
```

`...` | Bare expressions for the exogenous regressors (such as `log(x)` ) |

## Examples

```
melb_rain |>
model(logistic = LOGISTIC(Wet ~ fourier(K = 5, period = "year")))
#> # A mable: 1 x 1
#> logistic
#> <model>
#> 1 <LOGISTIC>
```