# loess.control

##### Set Parameters for Loess

Set control parameters for `loess`

fits.

##### Usage

```
loess.control(surface = c("interpolate", "direct"),
statistics = c("approximate", "exact", "none"),
trace.hat = c("exact", "approximate"),
cell = 0.2, iterations = 4, iterTrace = FALSE, …)
```

##### Arguments

- surface
should the fitted surface be computed exactly (

`"direct"`

) or via interpolation from a kd tree? Can be abbreviated.- statistics
should the statistics be computed exactly, approximately or not at all? Exact computation can be very slow. Can be abbreviated.

- trace.hat
Only for the (default) case

`(surface = "interpolate", statistics = "approximate")`

: should the trace of the smoother matrix be computed exactly or approximately? It is recommended to use the approximation for more than about 1000 data points. Can be abbreviated.- cell
if interpolation is used this controls the accuracy of the approximation via the maximum number of points in a cell in the kd tree. Cells with more than

`floor(n*span*cell)`

points are subdivided.- iterations
the number of iterations used in robust fitting, i.e. only if

`family`

is`"symmetric"`

.- iterTrace
logical (or integer) determining if tracing information during the robust iterations (

`iterations`

\(\ge 2\)) is produced.- …
further arguments which are ignored.

##### Value

A list with components

##### See Also

*Documentation reproduced from package stats, version 3.5.0, License: Part of R 3.5.0*