Linear Hamiltonian systems on time scales: positivity of quadratic functionals

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Authors	HILSCHER Roman
Year of publication	2000
Type	Article in Periodical
Magazine / Source	Mathematical and Computer Modelling
MU Faculty or unit	Faculty of Science
Citation
Field	General mathematics
Keywords	time scale; (continuous and discrete) linear Hamiltonian system; disconjugacy; principal solution; quadratic functional
Description	In this work we consider a linear Hamiltonian system (H) x^\Delta = A_t x^\sigma + B_t u, u^\Delta = -C_t x^\sigma - A_t^T u on an arbitrary time scale T, which allows (among others) to treat both continuous and discrete linear Hamiltonian systems (as the special cases for T=R and T=Z) within one theory; to explain the discrepancies between these two theories while studying systems of the form (H). As a main result we prove that disconjugacy of the system (H) is a sufficient condition for positive definiteness of the quadratic functional associated with (H). The principal tool is the Picone identity on T. We derive also the corresponding Wronskian identity, Riccati equation in this general setting on time scales.
Related projects:	Differential and functional - differential equations Difference equations and their applications