# objsurf

##### Objective Function Surface

For a model that was fitted by optimisation, compute the values of the objective function in a neighbourhood of the optimal value.

##### Usage

`objsurf(x, …)`# S3 method for dppm
objsurf(x, ..., ngrid = 32, ratio = 1.5, verbose = TRUE)

# S3 method for kppm
objsurf(x, ..., ngrid = 32, ratio = 1.5, verbose = TRUE)

# S3 method for minconfit
objsurf(x, ..., ngrid = 32, ratio = 1.5, verbose = TRUE)

##### Arguments

- x
Some kind of model that was fitted by finding the optimal value of an objective function. An object of class

`"dppm"`

,`"kppm"`

or`"minconfit"`

.- …
Extra arguments are usually ignored.

- ngrid
Number of grid points to evaluate along each axis. Either a single integer, or a pair of integers. For example

`ngrid=32`

would mean a`32 * 32`

grid.- ratio
Number greater than 1 determining the range of parameter values to be considered. If the optimal parameter value is

`opt`

then the objective function will be evaluated for values between`opt/ratio`

and`opt * ratio`

.- verbose
Logical value indicating whether to print progress reports.

##### Details

The object `x`

should be some kind of model that was fitted
by maximising or minimising the value of an objective function.
The objective function will be evaluated on a grid of
values of the model parameters.

Currently the following types of objects are accepted:

an object of class

`"dppm"`

representing a determinantal point process. See`dppm`

.an object of class

`"kppm"`

representing a cluster point process or Cox point process. See`kppm`

.an object of class

`"minconfit"`

representing a minimum-contrast fit between a summary function and its theoretical counterpart. See`mincontrast`

.

The result is an object of class `"objsurf"`

which can be
printed and plotted: see `methods.objsurf`

.

##### Value

An object of class `"objsurf"`

which can be
printed and plotted.
Essentially a list containing entries `x`

, `y`

, `z`

giving the parameter values and objective function values.

##### See Also

##### Examples

```
# NOT RUN {
fit <- kppm(redwood ~ 1, "Thomas")
os <- objsurf(fit)
if(interactive()) {
plot(os)
contour(os, add=TRUE)
persp(os)
}
# }
```

*Documentation reproduced from package spatstat, version 1.59-0, License: GPL (>= 2)*