AbstractA projection‐recurrence method is applied to active and passive ladder networks with a tridiagonal interaction matrix to obtain a factorization of the response functions. The factors are partial chain parameters, determined by third order recurrences. For a ladder withNnodes, the number of arithmetic operations to calculate response functions ranges from 4Nto 6N. A diagrammatic representation is developed for passive ladders which makes it possible to obtain the partial chain parameters by inspection, and a compact formula for the node‐voltage response is presented for active doubly‐terminated la