19.4.2.2 Properties of the Anisotropy of the Motion

         property ::= DYN { ANISOTROPY } { X }
                          { ANISTROPY  } { V }

Note: the program will accept the above incorrect speling as well as the normal spelling.

This property specification extracts the anisotropy of the fluctuations. Since the principal axis transformation orders the second moment fluctuations by their size, one can measure the anisotropy of the motion using the following measure:

                        M2X
             -------------------------  -  1
                     2      2
                  M2Y  + M2Z       -12
             SQRT(-----------) + 10
                       2

where the second moments are in the principal axis system. For this measure, isotropic motion will yield an anisotropy of 0; motion along a single line will yield an anisotropy of 1,000,000,000,000. For large anisotropies, the measure will roughly yield the ratio of the dominant motion to the other motions. The anisotropy of X specifies the coordinate anisotropy; the anisotropy of V specifies the velocity anisotropy.