positive-definite metric, and thus cannot be used in relativistic contexts. History Dyadic tensors were historically the first approach to formulating second-order tensors, similarly triadic tensors for third-order tensors, and so on. Cartesian tensors use tensor index notation, in which the variance may be glossed over and is often ignored, since the components remain unchanged by raising and lowering indices. See also Tensor algebra Tensor calculus Tensors in curvilinear coordinates Rotation group References General references Further reading and applications External links Cartesian Tensors V. N. Kaliakin, Brief Review of Tensors, University of Delaware R. E. Hunt, Cartesian Tensors, University of Cambridge Linear algebra Tensors Applied mathematics