relocate: Relocate Tangent Representations to a New Reference Point

In riemtan: Riemannian Metrics for Symmetric Positive Definite Matrices

Relocate Tangent Representations to a New Reference Point

Description

Changes the reference point for tangent space representations on a Riemannian manifold. Supports parallel processing via the futureverse framework for improved performance on large datasets.

Usage

relocate(old_ref, new_ref, images, met, progress = FALSE)

Arguments

old_ref	A reference point on the manifold to be replaced. Must be an object of class dppMatrix from the Matrix package.
new_ref	The new reference point on the manifold. Must be an object of class dppMatrix from the Matrix package.
images	A list of tangent representations relative to the old reference point. Each element in the list must be an object of class dspMatrix.
met	A metric object of class rmetric, containing functions for Riemannian operations (logarithmic map, exponential map, vectorization, and inverse vectorization).
progress	Logical indicating whether to show progress during computation (default: FALSE). Requires progressr package.

Details

This function uses parallel processing when the number of images exceeds a threshold and parallel processing is enabled via set_parallel_plan(). For small datasets, sequential processing is used automatically to avoid parallelization overhead.

Value

A list of tangent representations relative to the new reference point. Each element in the returned list will be an object of class dspMatrix.

Examples

if (requireNamespace("Matrix", quietly = TRUE)) {
  library(Matrix)
  data(airm)
  old_ref <- diag(2) |>
    Matrix::nearPD() |>
    _$mat |>
    Matrix::pack()
  new_ref <- diag(c(2, 3)) |>
    Matrix::nearPD() |>
    _$mat |>
    Matrix::pack()
  images <- list(
    diag(2) |> Matrix::symmpart() |> Matrix::pack(),
    diag(c(1, 0.5)) |> Matrix::symmpart() |> Matrix::pack()
  )
  relocate(old_ref, new_ref, images, airm)
}

riemtan documentation built on Nov. 11, 2025, 1:06 a.m.