The single dot product of the spheroid is defined as

δ_{z} = ⋅, |
(15.181) |

where
is a unit vector parallel to the XH vector.
is a unit vector parallel to the unique axis of the diffusion tensor and can be expressed using the spherical angles where *θ* is the polar angle and *φ* is the azimuthal angle as

= . | (15.182) |

The relax user manual (PDF), created 2020-08-26.