In §C.12, the theory of multiport scattering was derived, i.e.,
the reflections and transmissions that occur when
digital
waveguides having wave impedances
are connected together. It
was noted that when
is a power of two, there are
no multiplies in the scattering relations Eq.(C.129), and that
this fact has been used to build multiply-free reverberators and other
structures using digital waveguide meshes
[435,523,147,400,525,526,402,403,405,55,204,325,324,326,427,33].