Tsuk-White Algorithm (TWA) Fitting Method

By default, SIwave uses a proprietary fitting method, the Tsuk-White Algorithm (TWA) for calculating the state-space matrices. The TWA algorithm for state-space fitting is an alternative to rational fitting. TWA generates the poles of the state-space fit from the singular value decomposition of Loewner matrices derived from the input data. Unlike rational fitting, TWA is not an iterative procedure and can produce high-quality state-space fits in much less time than rational fitting. The TWA algorithm may succeed where rational fitting produces a bad fit or a fit that is good but nonpassive on a problem too big for passivity enforcement.