翻訳と辞書 |
Semi-elliptic operator : ウィキペディア英語版 | Semi-elliptic operator In mathematics — specifically, in the theory of partial differential equations — a semi-elliptic operator is a partial differential operator satisfying a positivity condition slightly weaker than that of being an elliptic operator. Every elliptic operator is also semi-elliptic, and semi-elliptic operators share many of the nice properties of elliptic operators: for example, much of the same existence and uniqueness theory is applicable, and semi-elliptic Dirichlet problems can be solved using the methods of stochastic analysis. ==Definition==
A second-order partial differential operator ''P'' defined on an open subset Ω of ''n''-dimensional Euclidean space R''n'', acting on suitable functions ''f'' by : is said to be semi-elliptic if all the eigenvalues ''λ''''i''(''x''), 1 ≤ ''i'' ≤ ''n'', of the matrix ''a''(''x'') = (''a''''ij''(''x'')) are non-negative. (By way of contrast, ''P'' is said to be elliptic if ''λ''''i''(''x'') > 0 for all ''x'' ∈ Ω and 1 ≤ ''i'' ≤ ''n'', and uniformly elliptic if the eigenvalues are uniformly bounded away from zero, uniformly in ''i'' and ''x''.) Equivalently, ''P'' is semi-elliptic if the matrix ''a''(''x'') is positive semi-definite for each ''x'' ∈ Ω.
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「Semi-elliptic operator」の詳細全文を読む
スポンサード リンク
翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|