The capacitance of given structures may be computed by solving the electrostatic field and calculating the total energy of the field. The capacitance is directly releted to the energy and to the potential difference. The first figure shows the isocontours of the electric potential between two charged cylinders. The cylinders are separated by two materials with different permittivities.

For multibody cases the capacitance is a matrix. Elmer has permutation algoritms which allow automatic definition of the capacitance matrix. The matrix is always symmetric and thus has N(N+1)/2 unknowns. The second figure shows one permutation for a case were the capacitance matrix for five bodies was defined.