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Lagrangian optics〔Vasudevan Lakshminarayanan et al., ''Lagrangian Optics'', Springer Netherlands, 2011 (978-0792375821 )〕 and Hamiltonian optics〔H. A. Buchdahl, ''An Introduction to Hamiltonian Optics'', Dover Publications, 1993 (978-0486675978 )〕 are two formulations of geometrical optics which share much of the mathematical formalism with Lagrangian mechanics and Hamiltonian mechanics. ==Hamilton's principle== (詳細はphysics, Hamilton's principle states that the evolution of a system described by generalized coordinates between two specified states at two specified parameters ''σ''''A'' and ''σ''''B'' is a stationary point (a point where the variation is zero), of the action functional, or : where . Condition is valid if and only if the Euler-Lagrange equations are satisfied : with . The momentum is defined as : and the Euler-Lagrange equations can then be rewritten as : where . A different approach to solving this problem consists in defining a Hamiltonian (taking a Legendre transform of the Lagrangian) as : for which a new set of differential equations can be derived by looking at how the total differential of the Lagrangian depends on parameter ''σ'', positions and their derivatives relative to ''σ''. This derivation is the same as in Hamiltonian mechanics, only with time ''t'' now replaced by a general parameter ''σ''. Those differential equations are the Hamilton's equations : with . Hamilton's equations are first-order differential equations, while Euler-Lagrange's equations are second-order. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Hamiltonian optics」の詳細全文を読む スポンサード リンク
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