One case in which ε is "not" a symmetric matrix is for magneto-optic materials, in which case the usual statement of Lorentz reciprocity does not hold (see below for a generalization, however). If we allow magneto-optic materials, but restrict ourselves to the situation where material "absorption is negligible", then ε and μ are in general 3×3 complex Hermitian matrices. In this case, the operator formula_99 is Hermitian under the "conjugated" inner product formula_100, and a variant of the reciprocity theorem still holds: