The principal aim of this paper is to state and prove the so called Reid roundabout theorem for symplectic dynamic system (S) $z\backslash Delta=S$_tz on an arbitrary time scale T, so that the well known case of differential linear Hamiltonian systems (T=R) and recently developed case of discrete symplectic systems (T=Z) are unified. We list conditions which are equivalent to the positivity of the quadratic functional associated with (S), e.g. disconjugacy (in terms of no focal points of a conjoined basis) of (S), no generalized zeros for vector solutions of (S), the existence of a solution to the corresponding Riccati matrix equation. A certain normality assumption is employed. The result requires treatment of the quadratic functionals both with general and separated boundary conditions.

Last change: October 5, 2000. (c) Roman Hilscher