corGaus  R Documentation 
This function is a constructor for the corGaus
class,
representing a Gaussian spatial correlation structure. Letting
d
denote the range and n
denote the nugget
effect, the correlation between two observations a distance
r
apart is \exp((r/d)^2)
when no nugget
effect is present and (1n) \exp((r/d)^2)
when a nugget effect is assumed. Objects created using this
constructor must later be initialized using the appropriate
' Initialize
method.
corGaus(value, form, nugget, metric, fixed)
value 
an optional vector with the parameter values in
constrained form. If 
form 
a one sided formula of the form 
nugget 
an optional logical value indicating whether a nugget
effect is present. Defaults to 
metric 
an optional character string specifying the distance
metric to be used. The currently available options are

fixed 
an optional logical value indicating whether the
coefficients should be allowed to vary in the optimization, or kept
fixed at their initial value. Defaults to 
an object of class corGaus
, also inheriting from class
corSpatial
, representing a Gaussian spatial correlation
structure.
JosÃ© Pinheiro and Douglas Bates bates@stat.wisc.edu
Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.
Venables, W.N. and Ripley, B.D. (2002) "Modern Applied Statistics with S", 4th Edition, SpringerVerlag.
Littel, Milliken, Stroup, and Wolfinger (1996) "SAS Systems for Mixed Models", SAS Institute.
Pinheiro, J.C., and Bates, D.M. (2000) "MixedEffects Models in S and SPLUS", Springer.
Initialize.corStruct
,
summary.corStruct
,
dist
sp1 < corGaus(form = ~ x + y + z)
# example lme(..., corGaus ...)
# Pinheiro and Bates, pp. 222249
fm1BW.lme < lme(weight ~ Time * Diet, BodyWeight,
random = ~ Time)
# p. 223
fm2BW.lme < update(fm1BW.lme, weights = varPower())
# p 246
fm3BW.lme < update(fm2BW.lme,
correlation = corExp(form = ~ Time))
# p. 249
fm8BW.lme < update(fm3BW.lme, correlation = corGaus(form = ~ Time))
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