airm_exp: Compute the AIRM Exponential

In riemtan: Riemannian Metrics for Symmetric Positive Definite Matrices

Compute the AIRM Exponential

Description

This function computes the Riemannian exponential map for the Affine-Invariant Riemannian Metric (AIRM).

Usage

airm_exp(sigma, v)

Arguments

sigma	A symmetric positive-definite matrix of class dppMatrix, representing the reference point.
v	A tangent vector of class dspMatrix, to be mapped back to the manifold at sigma.

Value

A symmetric positive-definite matrix of class dppMatrix.

Examples

if (requireNamespace("Matrix", quietly = TRUE)) {
  library(Matrix)
  sigma <- diag(2) |>
    Matrix::nearPD() |>
    _$mat |>
    Matrix::pack()
  v <- diag(c(1, 0.5)) |>
    Matrix::symmpart() |>
    Matrix::pack()
  airm_exp(sigma, v)
}

riemtan documentation built on June 8, 2025, 9:39 p.m.