georob (version 0.3-5)

default.aniso: Setting Default Values of Variogram Parameters

Description

Helper functions to set sensible default values for anisotropy parameters and for controlling what variogram and anisotropy parameters should be estimated.

Usage

default.aniso(f1 = 1., f2 = 1., omega = 90., phi = 90., zeta = 0.)
default.fit.param(
  variance = TRUE, snugget = FALSE, nugget = TRUE, scale = TRUE, 
  alpha = FALSE, beta = FALSE, delta = FALSE, gamma = FALSE, 
  kappa = FALSE, lambda = FALSE, mu = FALSE, nu = FALSE)
  
default.fit.aniso(f1 = FALSE, f2 = FALSE, omega = FALSE, 
  phi = FALSE, zeta = FALSE)

Arguments

variance

variance (sill \(\sigma^2\)) of the auto-correlated component of the Gaussian random field \(B(\mbox{\boldmath$s$\unboldmath})\).

snugget

variance (spatial nugget \(\sigma^2_{\mathrm{n}}\)) of the seemingly spatially uncorrelated component of \(B(\mbox{\boldmath$s$\unboldmath})\) (micro-scale spatial variation; default value snugget = 0).

nugget

variance (nugget \(\tau^2\)) of the independent errors \(\varepsilon(\mbox{\boldmath$s$\unboldmath})\).

scale

range parameter (\(\alpha\)) of the variogram.

alpha, beta, delta, gamma, kappa, lambda, mu, nu

names of additional variogram parameters such as the smoothness parameter \(\nu\) of the Whittle-Mat<U+008E>rn model (see RMmodel and param.names).

f1

ratio \(f_1\) of lengths of second and first semi-principal axes of an ellipsoidal surface with constant semi-variance in \(\mathrm{I}\!\mathrm{R}^3\) (default f1 = 1).

f2

ratio \(f_2\) of lengths of third and first semi-principal axes of the semi-variance ellipsoid (default f2 = 1).

omega

azimuth in degrees of the first semi-principal axis of the semi-variance ellipsoid (default omega = 90).

phi

90 degrees minus altitude of the first semi-principal axis of the semi-variance ellipsoid (default phi = 90).

zeta

angle in degrees between the second semi-principal axis and the direction of the line defined by the intersection between the \(x\)-\(y\)-plane and the plane orthogonal to the first semi-principal axis of the semi-variance ellipsoid through the origin (default zeta = 0).

Value

Either a named numeric with initial values of anisotropy parameters (default.aniso) or named logical vector, controlling what parameters should be estimated (default.fit.param default.fit.aniso).

See Also

georobIntro for a description of the model and a brief summary of the algorithms; georob for (robust) fitting of spatial linear models.

Examples

# NOT RUN {
default.aniso(f1 = 0.5, omega = 45)
default.fit.param(scale=FALSE, alpha = TRUE)
default.fit.aniso(f1 = TRUE, omega = TRUE)
# }