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Invariants of tensors. In mathematics, in the fields of multilinear algebra and representation theory, the principal invariants of the second rank tensor are the coefficients of the characteristic polynomial [1] where is the identity operator and are the roots of the polynomial and the eigenvalues of . More broadly,any scalar-valued function is ...
Cauchy stress tensor. In continuum mechanics, the Cauchy stress tensor (symbol , named after Augustin-Louis Cauchy), also called true stress tensor[1] or simply stress tensor, completely defines the state of stress at a point inside a material in the deformed state, placement, or configuration. The second order tensor consists of nine ...
Tor functor. In mathematics, the Tor functors are the derived functors of the tensor product of modules over a ring. Along with the Ext functor, Tor is one of the central concepts of homological algebra, in which ideas from algebraic topology are used to construct invariants of algebraic structures.
Lode coordinates. Surfaces on which the invariants , , are constant. Plotted in principal stress space. The red plane represents a meridional plane and the yellow plane an octahedral plane. Lode coordinates or Haigh–Westergaard coordinates . [1] are a set of tensor invariants that span the space of real, symmetric, second-order, 3-dimensional ...
Definition. A tensor field of type (p, q) is a section. where V is a vector bundle on M, V* is its dual and ⊗ is the tensor product of vector bundles. Equivalently, it is a collection of elements Tx ∈ Vx⊗p ⊗ (Vx*) ⊗q for all points x ∈ M, arranging into a smooth map T : M → V⊗p ⊗ (V*) ⊗q. Elements Tx are called tensors.
Tensor contraction. In multilinear algebra, a tensor contraction is an operation on a tensor that arises from the canonical pairing of a vector space and its dual. In components, it is expressed as a sum of products of scalar components of the tensor (s) caused by applying the summation convention to a pair of dummy indices that are bound to ...
Let X be an affine space over a field k, and V be its associated vector space. An affine transformation is a bijection f from X onto itself that is an affine map; this means that a linear map g from V to V is well defined by the equation () = (); here, as usual, the subtraction of two points denotes the free vector from the second point to the first one, and "well-defined" means that ...
The group SU (3) is a subgroup of group U (3), the group of all 3×3 unitary matrices. The unitarity condition imposes nine constraint relations on the total 18 degrees of freedom of a 3×3 complex matrix. Thus, the dimension of the U (3) group is 9. Furthermore, multiplying a U by a phase, eiφ leaves the norm invariant.