# objsurf

From spatstat v1.36-0
by Adrian Baddeley

##### 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 class 'kppm':
objsurf(x, ..., ngrid = 32, ratio = 1.5, verbose = TRUE)

## S3 method for class '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
`"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
`"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`

.

`"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

```
fit <- kppm(redwood, ~1, "Thomas")
os <- objsurf(fit)
if(interactive()) {
plot(os)
contour(os, add=TRUE)
persp(os)
}
```

*Documentation reproduced from package spatstat, version 1.36-0, License: GPL (>= 2)*

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