Computer-aided-manipulation of Mason´s formula and its application

Presents a method to determine the symbolic gain of a linear system via S.J. Mason´s formula (1953, 1956). A combined searching algorithm which is based on the breadth-first and depth-first searching algorithms in a directed graph is devised to find the forward paths and loops in the linear system. Mason´s formula is then determined via touching-nontouching matches of forward paths and loops in the system. A SPICE-like system description language is also proposed to describe the linear system, so that this algorithm can be coded easily in C language. In comparison with other approaches, this method is more systematic and needs no complicated matrix operations