transform_parameters_anisotropic: Transform Anisotropic SPDE Model Parameters to Original Scale

In rSPDE: Rational Approximations of Fractional Stochastic Partial Differential Equations

Transform Anisotropic SPDE Model Parameters to Original Scale

Description

This function takes a vector of transformed parameters and applies the appropriate transformations to return them in the original scale for use in anisotropic SPDE models.

Usage

transform_parameters_anisotropic(theta, nu_upper_bound = NULL)

Arguments

theta	A numeric vector of length 4 or 5, containing the transformed parameters in this order: lhx The logarithmic representation of hx. lhy The logarithmic representation of hy. logit_hxy The logit-transformed representation of hxy. lsigma The logarithmic representation of sigma. lnu (optional) The logarithmic representation of nu. If not provided, nu is not returned.
nu_upper_bound	(optional) A numeric value representing the upper bound for the smoothness parameter nu. This is only used, and must be provided, if lnu is provided.

Value

A named list with the parameters in the original scale:

hx

The original scale for hx (exponential of lhx).

hy

The original scale for hy (exponential of lhy).

hxy

The original scale for hxy (inverse logit transformation of logit_hxy).

sigma

The original scale for sigma (exponential of lsigma).

nu (optional)

The original scale for nu (using the forward_nu transformation). Only included if lnu is provided.

Examples

# With lnu
theta <- c(log(0.1), log(0.2), log((0.3 + 1) / (1 - 0.3)), log(0.5), log(1))
nu_upper_bound <- 2
transform_parameters_anisotropic(theta, nu_upper_bound)

# Without lnu
theta <- c(log(0.1), log(0.2), log((0.3 + 1) / (1 - 0.3)), log(0.5))
transform_parameters_anisotropic(theta)

rSPDE documentation built on Jan. 26, 2026, 9:06 a.m.