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Last data update: 2014.03.03

R: Setting Default Values of Variogram Parameters

default.aniso

R Documentation

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 σ^2) of the auto-correlated component of the Gaussian random field B(s).
`snugget`	variance (spatial nugget σ^2_n) of the seemingly spatially uncorrelated component of B(s) (micro-scale spatial variation; default value `snugget = 0`).
`nugget`	variance (nugget τ^2) of the independent errors ε(s).
`scale`	range parameter (α) of the variogram.
`alpha, beta, delta, gamma, kappa, lambda, mu, nu`	names of additional variogram parameters such as the smoothness parameter ν of the Whittle-Mat¬érn 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 semivariance in R^3 (default `f1 = 1`).
`f2`	ratio f_2 of lengths of third and first semi-principal axes of the semivariance ellipsoid (default `f2 = 1`).
`omega`	azimuth in degrees of the first semi-principal axis of the semivariance ellipsoid (default `omega = 90`).
`phi`	90 degrees minus altitude of the first semi-principal axis of the semivariance 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 semivariance 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).

Author(s)

Andreas Papritz andreas.papritz@env.ethz.ch

Examples

default.aniso(f1 = 0.5, omega = 45)
default.fit.param(scale=FALSE, alpha = TRUE)
default.fit.aniso(f1 = TRUE, omega = TRUE)