matern {asreml} | R Documentation |
Model function for an extended Matern class.
mtrn(x, y, phi=NA, nu=0.5, delta=1.0, alpha=0.0, lambda=2) mtrnv(x, y, phi=NA, nu=0.5, delta=1.0, alpha=0.0, lambda=2, init=0.1) mtrnh(x, y, phi=NA, nu=0.5, delta=1.0, alpha=0.0, lambda=2, init=0.1)
x |
An object in |
y |
An object in |
phi |
The range parameter; default |
nu |
The smoothness parameter; default 0.5. |
delta |
Governs geometric anisotropy; default 1.0. |
alpha |
Governs geometric anisotropy; default 0.0. |
lambda |
Specifies the choice of metric: 2 is Euclidean distance (default), and 1 is city block. |
init |
An optional vector of initial values for any variance parameters,
with an optional |
The mtrn
special function implements an extended Matern
class which accomodates geometric anisotropy and a choice of
metrics for random fields observed in two dimensions (Haskard
et al., 2007). See the User Guide for details.
If an argument to mtrn
is numeric, it is treated as a
starting value for estimation and given the constraint code
P
(positive). This behaviour can be altered by concatenating
the numeric value followed by the constraint code (“P”,
“U” or “F”) into a character string. If an argument
is absent from the call, the corresponding parameter is held fixed
at its default value.
asr_mtrnv
: Matern variance model,
homogeneous variance form.
asr_mtrnh
: Matern variance model,
heterogeneous variance form.
Haskard KA, Cullis BR, Verbyla AP (2007). “Anisotropic Matern correlation and spatial prediction using REML.” Journal of Agricultural and Biological Sciences, 12, 147-160.