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In mathematics and, specifically, real analysis, the Dini derivatives (or Dini derivates) are a class of generalizations of the derivative. They were introduced by Ulisse Dini. The upper Dini derivative, which is also called an upper right-hand derivative, of a continuous function : is denoted by and defined by : where is the supremum limit and the limit is a one-sided limit. The lower Dini derivative, , is defined by : where is the infimum limit. If is defined on a vector space, then the upper Dini derivative at in the direction is defined by : If is locally Lipschitz, then is finite. If is differentiable at , then the Dini derivative at is the usual derivative at . ==Remarks== * Sometimes the notation is used instead of and is used instead of 〔 * Also, : and : * So when using the notation of the Dini derivatives, the plus or minus sign indicates the left- or right-hand limit, and the placement of the sign indicates the infimum or supremum limit. * On the extended reals, each of the Dini derivatives always exist; however, they may take on the values or at times (i.e., the Dini derivatives always exist in the extended sense). 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「Dini derivative」の詳細全文を読む スポンサード リンク
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