1. A method for analyzing a circuit with transmission lines, comprising the steps of: based on coupling factors, determining which sources influence each of a plurality of transmission lines; computing transmission line parameters based on the sources which influence each transmission line; analyzing a transient or frequency response for each transmission line by segmenting each line to perform an analysis on that line; and repeating the step of analyzing using waveforms determined in a previous iteration until convergence to a resultant waveform has occurred.