RMdagum: Dagum Covariance Model Family

Description Usage Arguments Details Value References See Also Examples

View source: R/RMmodels.R

Description

RMdagum is a stationary isotropic covariance model. The corresponding covariance function only depends on the distance r ≥ 0 between two points and is given by

C(r) = 1-(1+r^(-β))^(-γ / β).

The parameters β and γ can be varied in the intervals (0,1] and (0,1), respectively.

Usage

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Arguments

beta

numeric in (0,1]

gamma

numeric in (0,1)

var,scale,Aniso,proj

optional arguments; same meaning for any RMmodel. If not passed, the above covariance function remains unmodified.

Details

Like the generalized Cauchy model the Dagum family can be used to model fractal dimension and Hurst effect. For a comparison of these see Berg, C. and Mateau, J. and Porcu, E. (2008). This paper also establishes valid parameter choices for the Dagum family, but be careful because therein the model is parameterized differently.

Value

RMdagum returns an object of class RMmodel.

References

See Also

RMmodel, RFsimulate, RFfit.

Examples

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RFoptions(seed=0) ## *ANY* simulation will have the random seed 0; set
##                   RFoptions(seed=NA) to make them all random again

model <- RMdagum(beta=0.5, gamma=0.5, scale=0.2)
x <- seq(0, 10, 0.02)
plot(model)
plot(RFsimulate(model, x=x))

RandomFields documentation built on Jan. 19, 2022, 1:06 a.m.