Zeta function (operator)
The zeta function of a mathematical operator is a function defined as
for those values of s where this expression exists, and as an analytic continuation of this function for other values of s. Here "tr" denotes a functional trace.
The zeta function may also be expressible as a spectral zeta function in terms of the eigenvalues of the operator by
It is used in giving a rigorous definition to the functional determinant of an operator, which is given by
The Minakshisundaram–Pleijel zeta function is an example, when the operator is the Laplacian of a compact Riemannian manifold.
One of the most important motivations for Arakelov theory is the zeta functions for operators with the method of heat kernels generalized algebro-geometrically.
