Efficient method for computing noise in a general purpose CAD program in APL

An efficient technique is implemented in a general-purpose CAD (computer-aided design) program to compute noise in electric circuits. In this method, a preordered, sparsely stored circuit matrix is transposed in an easy but subtle manner. As a consequence, one frequency-domain (AC) analysis is needed to compute noise at an output regardless of the number of noise sources. Unlike other programs that compute noise, the Interactive Circuit Design Program used allows arbitrary type of noise expressions that could be functions of an arbitrary set of parameters, voltages, currents, and frequency, and therefore the most common noise sources are covered. Examples are given.