corSpher class,
representing a spherical spatial correlation structure. Letting
$d$ denote the range and $n$ denote the nugget
effect, the correlation between two observations a distance
$r < d$ apart is $1-1.5(r/d)+0.5(r/d)^3$ when no
nugget effect is present and $(1-n)
(1-1.5(r/d)+0.5(r/d)^3)$
when a nugget effect is assumed. If $r \geq d$ the
correlation is zero. Objects created using this constructor must later
be initialized using the appropriate Initialize method.corSpher(value, form, nugget, metric, fixed)nugget is FALSE, value can
have only one element, corresponding to the "range" of the
spherical correlation structure, which must be great~ S1+...+Sp, or
~ S1+...+Sp | g, specifying spatial covariates S1
through Sp and, optionally, a grouping factor g.
When a grouping factor is presenFALSE."euclidean" for the root sum-of-squares of distances;
"maximum" for the maximum difference; and "manhattanFALSE, in which case
the coefficients are allowed to vary.corSpher, also inheriting from class
corSpatial, representing a spherical spatial correlation
structure.Initialize.corStruct, distsp1 <- corSpher(form = ~ x + y)Run the code above in your browser using DataLab