Anderson, B. D.O.Moore, J. B.2026-01-022026-01-020018-9286ORCID:/0000-0002-1493-4774/work/174739800https://hdl.handle.net/1885/733803075Finite dimensional systems with time-varying feedback, which satisfy the conditions of the circle criterion for stability, are considered. A recent result giving a system theory description of positive real matrices is used to generate Liapunov functions.2en196810.1109/TAC.1968.109886584909524366