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OGS
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A local coordinate system used for tensor transformations.
It offers a simple way for input of anisotropic tensors w.r.t. a coordinate system. The basis vectors form a transformation matrix R = (e_0, e_1, e_2). For a given anisotropic tensor A parameter with the corresponding [tag] use_local_coordinate_system the tensor is rotated according to the formula: A' = R\cdot A\cdot R^T.
For computations in transverse isotropic material models, we can create a coordinate system with only one base, where the last base is explicitly given. The other bases are set as implicit and computed from the given base as follows:
unit_direction, is set as the third base, {\vec e}_2. An arbitrary unit vector orthogonal to {\vec e}_2 is selected as the second base e_1, and the first base {\vec e}_0 is calculated as {\vec e}_0 = {\vec e}_1 \times {\vec e}_2. 
1.12.0