Warped geometries of Segre-Veronese manifolds

Abstract: Segre-Veronese manifolds are smooth manifolds consisting of partially symmetric rank-$1$ tensors. They are naturally viewed as submanifolds of a Euclidean space of tensors. However, they can also be equipped with other metrics than their induced metrics, such as warped product metrics. We investigate a one-parameter family of warped geometries, which includes the standard Euclidean geometry, and whose parameter controls by how much spherical tangent directions are weighted relative to radial tangent directions. We compute the exponential and logarithmic maps of these warped Segre-Veronese manifolds, including the corresponding starting and connecting geodesics. A closed formula for the intrinsic distance between points on the warped Segre-Veronese manifold is presented. We determine for which warping parameters Segre-Veronese manifolds are geodesically connected and show that they are not geodesically connected in the standard Euclidean geometry. The benefits of connecting geodesics may outweigh using the Euclidean geometry in certain applications. One such application is presented: numerically computing the Riemannian center of mass for averaging rank-$1$ tensors.