ABSTRACT
The motivation for constructing the solid harmonics was that they formed, in terms of homogeneous functions, a particular set of solutions to Laplace’s equation. While the relevance of Laplace’s equation cannot be minimized, the differential properties of the harmonics are fundamentally statements about their responses to infinitesimal rotations of the coordinate system, or, equivalently, of the vectors r and a. An infinitesimal rotation is described by a vector delta omega, specifying the axis and angle of rotation.
