  This letter presents a three-dimensional form of governing equations of
generalized dynamics of 18-fold symmetry soft-matter quasicrystals, according
to the dynamics basis there are first and second phason elementary excitations
apart from phonons and fluid phonon. In the derivation, the group
representation theory is a key point. The complete form of the theory includes
an equation of state. The governing equations present some important meaning in
the study on thermodynamics of the matter which is also introduced.
