Extract the trend formula, or the terms in the trend formula, in a fitted Gibbs point process model.

```
# S3 method for ppm
formula(x, …)
# S3 method for ppm
terms(x, …)
```

x

An object of class `"ppm"`

,
representing a fitted point process model.

…

Arguments passed to other methods.

See the help files for the corresponding generic functions.

These functions are methods for the generic commands
`formula`

and
`terms`

for the class `"ppm"`

.

An object of class `"ppm"`

represents a fitted
Poisson or Gibbs point process model.
It is obtained from the model-fitting function `ppm`

.

The method `formula.ppm`

extracts the trend formula from the
fitted model `x`

(the formula originally specified as the
argument `trend`

to `ppm`

).
The method `terms.ppm`

extracts the individual
terms in the trend formula.

`ppm`

,
`as.owin`

,
`coef.ppm`

,
`extractAIC.ppm`

,
`fitted.ppm`

,
`logLik.ppm`

,
`model.frame.ppm`

,
`model.matrix.ppm`

,
`plot.ppm`

,
`predict.ppm`

,
`residuals.ppm`

,
`simulate.ppm`

,
`summary.ppm`

,
`update.ppm`

,
`vcov.ppm`

.

# NOT RUN { data(cells) fit <- ppm(cells, ~x) formula(fit) terms(fit) # }