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Loosely speaking, a residual is the error in a result. To be precise, suppose we want to find ''x'' such that : Given an approximation ''x''0 of ''x'', the residual is : whereas the error is : If we do not know ''x'' exactly, we cannot compute the error but we can compute the residual. ==Residual of the approximation of a function== Similar terminology is used dealing with differential, integral and functional equations. For the approximation of the solution of the equation : , the residual can either be the function : or can be said to be the maximum of the norm of this difference : over the domain , where the function is expected to approximate the solution , or some integral of a function of the difference, for example: : In many cases, the smallness of the residual means that the approximation is close to the solution, i.e., : In these cases, the initial equation is considered as well-posed; and the residual can be considered as a measure of deviation of the approximation from the exact solution. 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「Residual (numerical analysis)」の詳細全文を読む スポンサード リンク
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