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In differential geometry, the Willmore energy is a quantitative measure of how much a given surface deviates from a round sphere. Mathematically, the Willmore energy of a smooth closed surface embedded in three-dimensional Euclidean space is defined to be the integral of the square of the mean curvature minus the Gaussian curvature. It is named after the English geometer Thomas Willmore. ==Definition== Expressed symbolically, the Willmore energy of ''S'' is: : where is the mean curvature, is the Gaussian curvature, and ''dA'' is the area form of ''S''. For a closed surface, by the Gauss–Bonnet theorem, the integral of the Gaussian curvature may be computed in terms of the Euler characteristic of the surface, so : which is a topological invariant and thus independent of the particular embedding in that was chosen. Thus the Willmore energy can be expressed as : An alternative, but equivalent, formula is : where and are the principal curvatures of the surface. 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「Willmore energy」の詳細全文を読む スポンサード リンク
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