powerexp.gc: The Powered Exponential Correlation Function of Class...

In gcKrig: Analysis of Geostatistical Count Data using Gaussian Copulas

The Powered Exponential Correlation Function of Class corr.gc

Description

The powered exponential correlation function in spatial statistics.

By default, range parameter is not available, so this function is used for likelihood inference and spatial prediction in function mlegc and predgc. Users need to specify the shape parameter kappa and if the correlation model includes a nugget effect nugget = TRUE or not nugget = FALSE.

When both range and nugget parameters are given, the function is used for simulation with function simgc in package gcKrig.

Usage

powerexp.gc(range = NULL, kappa = 1, nugget = TRUE)

Arguments

range	a non-negative scalar of the range parameter in powered exponential correlation function.
kappa	a scalar between 0 and 2; the value of the shape parameter in the powered exponential correlation function.
nugget	the nugget effect of the correlation function. If specified, it must be a scalar between 0 and 1.

Details

The powered exponential correlation function with a nugget τ^2 is of the form:

ρ(h) = (1-τ^2) exp((-h/φ)^κ)

when h > 0 and ρ(h) = 1 when h = 0. Here h is distance, phi is range parameter, kappa is the shape parameter and tau^2 is the nugget effect.

When using the powered exponential correlation function, note that 0<κ ≤ 2.

Value

An object of class corr.gc representing the correlation component.

Author(s)

Zifei Han [e-mail]

See Also

matern.gc, spherical.gc

gcKrig documentation built on July 3, 2022, 1:05 a.m.