  We present a technique novel in numerical methods. It compiles the domain of
the numerical methods as a discretized volume. Congruent elements are glued
together to compile the domain over which the solution of a boundary value
problem of a linear operator is sought. We associate a group and a graph to
that volume. When the group is symmetry of the boundary value problem under
investigation, one can specify the structure of the solution, and find out if
there are equispectral volumes of a given type. We show that similarity of the
so called auxiliary matrices is sufficient and necessary for two discretized
volumes to be equispectral. A simple example demonstrates the feasibility of
the suggested method.
