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In mathematics the indefinite sum operator (also known as the antidifference operator), denoted by or ,〔(On Computing Closed Forms for Indefinite Summations. Yiu-Kwong Man. J. Symbolic Computation (1993), 16, 355-376 )〕〔"If ''Y'' is a function whose first difference is the function ''y'', then ''Y'' is called an indefinite sum of ''y'' and denoted Δ−1''y''" (''Introduction to Difference Equations'' ), Samuel Goldberg〕 is the linear operator, inverse of the forward difference operator . It relates to the forward difference operator as the indefinite integral relates to the derivative. Thus : More explicitly, if , then : If ''F''(''x'') is a solution of this functional equation for a given ''f''(''x''), then so is ''F''(''x'')+''C(x)'' for any periodic function ''C(x)'' with period 1. Therefore each indefinite sum actually represents a family of functions. However the solution equal to its Newton series expansion is unique up to an additive constant C. ==Fundamental theorem of discrete calculus== Indefinite sums can be used to calculate definite sums with the formula:〔"Handbook of discrete and combinatorial mathematics", Kenneth H. Rosen, John G. Michaels, CRC Press, 1999, ISBN 0-8493-0149-1〕 : 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「Indefinite sum」の詳細全文を読む スポンサード リンク
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