functional equation Special values Analogously to the Riemann zeta function, the values of the Dedekind zeta function at integers encode (at least conjecturally) important arithmetic data of the field K. For example, the analytic class number formula relates the residue at s = 1 to the class number h(K) of K, the regulator R(K) of K, the number w(K) of roots of unity in K, the absolute discriminant of K, and the number of real and complex places of K. Another example is at s = 0 where it has a zero whose order r is equal to the rank of the unit group of OK and the leading term is given by It follows from the functional equation that . Combining the functional equation and the fact that Γ(s) is infinite at all integers less than or equal to zero yields that ζK(s) vanishes at all negative even integers. It even vanishes at all negative odd integers unless K is totally real (i.e. r2 = 0; e.g. Q or a real quadratic field). In the totally real case, Carl Ludwig Siegel showed that ζK(s) is a non-zero rational number at negative odd integers. Stephen Lichtenbaum conjectured specific values for these rational numbers in terms of the algebraic K-theory of K. Relations to other L-functions For the case in which K is an abelian extension of Q, its Dedekind zeta function can be written as a product of Dirichlet L-functions. For example, when K is a quadratic field this shows that the ratio is the L-function L(s, χ), where χ is a Jacobi symbol used as Dirichlet character. That the zeta function of a quadratic field is a product of the Riemann zeta function and a certain Dirichlet L-function is an analytic formulation of the quadratic reciprocity law of Gauss. In general, if K is a Galois extension of Q with Galois group G, its Dedekind zeta function is the Artin L-function of the regular representation of G and hence has a factorization in terms of Artin L-functions of irreducible Artin representations of G. The relation with Artin L-functions shows that if L/K is a Galois extension then is holomorphic ( "divides" ): for general extensions the result would follow from the Artin conjecture for L-functions. Additionally, ζK(s) is the Hasse–Weil zeta function of Spec OK and the motivic L-function of the motive coming from the cohomology of Spec K.