= Notes on Jian et al. 2007 =

 * Diffusion tensors D inhabit a 6-dimensional space of 3-by-3 symmetric matrices.

  * The symmetry conditions reduce the 9 dimensions to 6 because 3 pairs of off-diagonal entries have to be equal.

 * The standard model of DT excitation is that brain matter is made up of a number of '''compartments'''