RMbcw: Model bridging stationary and intrinsically stationary processes

Description

RMbcw is a variogram model that bridges between some intrinsically stationary isotropic processes and some stationary ones. It reunifies the RMgenfbm ‘b’, RMgencauchy ‘c’ and RMdewijsian ‘w’.

The corresponding centered semi-variogram only depends on the distance $r \ge 0$ between two points and is given by $γ (r) = \frac{(r^{α} + 1)^{β / a l p h a} - 1}{2^{β / a l p h a} - 1}$ where $0 < \alpha \le 2$ and $\beta

Usage

RMbcw(alpha, beta, c, var, scale, Aniso, proj)

Arguments

alpha

a numerical value; should be in the interval (0,2].

beta

a numerical value; should be in the interval (-infty,2].

only for experts. If given, a not necessariy positive definite function $c-\gamma(r)$ is built.

var,scale,Aniso,proj

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

Value

RMbcw returns an object of class RMmodel

Details

For $betaa >0$, $beta<0$, $beta="0$" we="" have="" the="" generalised="" fractal="" brownian="" motion="" RMgenfbm, the generalised Cauchy model RMgencauchy, and the de Wisjian model RMdewijsian, respectively.

Hence its two arguments alpha and beta allow for modelling the smoothness and a wide range of tail behaviour, respectively.

References

Schlather, M (2014) A parameteric variogram model bridging between stationary and intrinsically stationary processes. arxiv 1412.1914.

Examples

Run this code

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

model <- RMbcw(alpha=1, beta=0.5)
x <- seq(0, 10, 0.02)
plot(model)
plot(RFsimulate(model, x=x))

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