3 papers
math.NA2026
Conditioning and interpolation error bounds for second-order Stiefel retractions with closed-form inverses
Rasmus Jensen, Ralf Zimmermann
Retractions provide a computationally efficient alternative to the Riemannian exponential and logarithm maps for practical data-processing tasks on manifolds. In particular, second…
math.NA2026
An new polar factor retraction on the Stiefel manifold with closed-form inverse
Rasmus Jensen, Ralf Zimmermann
Retractions are the workhorses in Riemannian computing applications, where computational efficiency is of the essence. This work introduces a new retraction on the compact Stiefel…
math.NA2025
Maximum volume coordinates for Grassmann interpolation: Lagrange, Hermite, and errors
Rasmus Jensen, Ralf Zimmermann
We present a novel approach to Riemannian interpolation on the Grassmann manifold. Instead of relying on the Riemannian normal coordinates, i.e. the Riemannian exponential and loga…