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1. Introduction
Fields is a collection of programs written in [R,S] for curve and function
fitting with an emphasis on spatial data. The major methods implemented as native
functions include:
- Tps: Thin Plate spline regression
- Krig: Spatial process estimate
(Kriging)
- krig.image: Spatial process estimate
for large 2-d problems.
The most distinctive feature of this module is that the Kriging functions allow you to supply a covariance function that is
written in native code. Some additional functions useful for spatial analysis are:
- vgram, COR : functions for
calculating variograms and correlograms.
- sim.rf : functions for
simulating spatial fields.
- smooth.image as.image, image.plot: Some useful functions
for working with image data.
- sreg, qsreg : 1-d smoothing splines
and 1-d quantile splines
There are also generic functions that support these methods such as:
- plot- diagnostic plots of fit
- summary- statistical summary of fit
- print- shorter version of summary
- surface- graphical display of fitted
surface
- predict- evaluation fit at arbitrary
points
- predict.se- prediction standard errors
at arbitrary points.
Section 2 presents the function for fitting thin plate splines. Many
of the features for splines carry over into the kriging function and so provides
a base for the general function fitting in section 3. Section 4 describes a
function for generating space filling designs and working with images. The last section is
a mathematical description of the estimates.
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