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In the mathematical theory of stochastic processes, local time is a stochastic process associated with diffusion processes such as Brownian motion, that characterizes the amount of time a particle has spent at a given level. Local time appears in various stochastic integration formulas, such as Tanaka's formula, if the integrand is not sufficiently smooth. It is also studied in statistical mechanics in the context of random fields. ==Formal definition== For a diffusion process , the local time of at the point is the stochastic process : where is the Dirac delta function. It is a notion invented by Paul Lévy. The basic idea is that is a (rescaled) measure of how much time has spent at up to time . It may be written as :, the local time can be expressed more simply as : 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「Local time (mathematics)」の詳細全文を読む スポンサード リンク
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