| matern_vs {asreml} | R Documentation |
Matern variance structure
Description
Model function for an extended Matern class
The mtrn special function implements an extended Matern
class (structure) which accommodates geometric anisotropy and a choice of
metrics for random fields observed in two dimensions (Haskard
et al., 2007). See the reference manual for further details.
Usage
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)
Arguments
x |
An object in |
y |
An object in |
phi |
The range parameter (default = |
nu |
The smoothness parameter (default = |
delta |
Governs geometric anisotropy (default = |
alpha |
Governs geometric anisotropy (default = |
lambda |
Specifies the choice of metric. Options are |
init |
An optional vector of initial values for any variance parameters,
with an optional |
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.
Functions
-
asr_mtrn(): Matern variance model; correlation form. -
asr_mtrnv(): Matern variance model; homogeneous variance form. -
asr_mtrnh(): Matern variance model; heterogeneous variance form.