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In mathematics, in the fields of multilinear algebra and representation theory, invariants of tensors are coefficients of the characteristic polynomial of the tensor ''A'':〔SPENCER, A. J. M. Continuum Mechanics. Longman, 1980.〕 :, where is the identity tensor and is the polynomial's indeterminate (it is important to bear in mind that a polynomial's indeterminate may also be a non-scalar as long as power, scaling and adding make sense for it, e.g., is legitimate, and in fact, quite useful). The first invariant of an ''n''×''n'' tensor A () is the coefficient for (because the coefficient for is always 1), the second invariant () is the coefficient for , etc., the ''n''th invariant is the free term. The definition of the ''invariants of tensors'' and specific notations used throughout the article were introduced into the field of rheology by Ronald Rivlin and became extremely popular there. In fact even the trace of a tensor is usually denoted as in the textbooks on rheology. ==Properties== The first invariant (trace) is always the sum of the diagonal components: : The ''n''th invariant is just , the determinant of (up to sign). The invariants do not change with rotation of the coordinate system (they are objective). Obviously, any function of the invariants only is also objective. 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「Invariants of tensors」の詳細全文を読む スポンサード リンク
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