RMsinepower: The Sinepower Covariance Model on the Sphere
In RandomFields: Simulation and Analysis of Random Fields

Description Usage Arguments Details Value Author(s) References See Also Examples

RMsinepower is an isotropic covariance model. The corresponding covariance function, the sine power function of Soubeyrand, Enjalbert and Sache, only depends on the angle 0 ≤ θ ≤ π between two points on the sphere and is given by

ψ(θ) = 1 - ( sin(θ/2) )^{α},

where 0 < α ≤ 2.

1	RMsinepower(alpha, var, scale, Aniso, proj)

`alpha`	a numerical value in (0,2]
`var,scale,Aniso,proj`	optional arguments; same meaning for any `RMmodel`. If not passed, the above covariance function remains unmodified.

For the sine power function of Soubeyrand, Enjalbert and Sache, see Gneiting, T. (2013), equation (17). For a more general form see RMchoquet.

RMsinepower returns an object of class RMmodel.

Christoph Berreth; \martin

Gneiting, T. (2013) Strictly and non-strictly positive definite functions on spheres Bernoulli, 19(4), 1327-1349.

RMmodel, RFsimulate, RFfit, spherical models, RMchoquet

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

RFoptions(coord_system="sphere")
model <- RMsinepower(alpha=1.7)
plot(model, dim=2)

## the following two pictures are the same
x <- seq(0, 0.4, 0.01)
z1 <- RFsimulate(model, x=x, y=x)
plot(z1)

x2 <- x * 180 / pi
z2 <- RFsimulate(model, x=x2, y=x2, coord_system="earth")
plot(z2)

stopifnot(all.equal(as.array(z1), as.array(z2)))

RFoptions(coord_system="auto")