1. A method of modeling an integrated circuit, comprising: specifying a layout for the integrated circuit, wherein the layout includes a plurality of devices arranged in a plurality of layers and a plurality of connections between the layers; specifying locations for a source point and an observation point for the integrated circuit; determining a plurality of static images for the source point and the observation point; determining a plurality of discrete complex images for the source point and the observation point; using a computer for determining a Green's-function value for the source point and the observation point by combining the static images and the discrete complex images; and saving at least some values based on the Green's-function value.