Geodesic distances between pairs of covariance matrices and geodesics between covariance matrices were calculated by the log-Euclidean method (Arsigny et al., 2006; Fletcher et al., 2004; Dryden et al., 2009) and implemented in Matlab. (See Section 6.2 for the mathematical details.). The pairwise distance calculation was applied to all pairs across age of the sex specific covariance matrices of the entire 27 coherence pairs and to the two regional blocks of coherence pairs (10 pairs each), anterior and posterior, which had identical topographic structure by the 10-20 system of scalp coordinates. This made possible comparisons between sexes and regions. Since there are 96 age specific covariance matrices for each block, there are 4560 pairwise distances calculate for each block. Additionally, for each age span distances between the covariance matrices of corresponding blocks were calculated. This provides a direct measure of the trajectories of between block differences, which could either be between sex distances for the same region or between region distances for the same sex.
