Fig. 1.

Statistical distance on tensors. Here we define a statistical distance between two tensors as (x₁ −μ)Σ⁻¹(x₂ – μ)^T, where Σ is the 6×6 matrix whose i, j^th element is the covariance between tensor component i in twin 1 (x₁) with tensor component j in twin 2 (x₂), and μ is the mean tensor of all the twins in log-Euclidean space. The green and blue 2D concentric ellipses on the center show isovalues of the Mahalanobis metric associated with this covariance matrix