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In mathematics, the (exponential) shift theorem is a theorem about polynomial differential operators (''D''-operators) and exponential functions. It permits one to eliminate, in certain cases, the exponential from under the ''D''-operators. The theorem states that, if ''P''(''D'') is a polynomial ''D''-operator, then, for any sufficiently differentiable function ''y'', : To prove the result, proceed by induction. Note that only the special case : needs to be proved, since the general result then follows by linearity of ''D''-operators. The result is clearly true for ''n'' = 1 since : Now suppose the result true for ''n'' = ''k'', that is, : Then, : This completes the proof. The shift theorem applied equally well to inverse operators: : There is a similar version of the shift theorem for Laplace transforms ( 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「Shift theorem」の詳細全文を読む スポンサード リンク
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