Stiffness Tensor Functions You will create two functions to generate a 2D stiffness tensor (i.e. a 3x3 matrix) for a long fiber composite: 1) using the rule-of-mixtures formulation and 2) using the Halpin-Tsai formulation. These must take as an input the Young's modulus of the fiber and matrix, the Poisson's ratio of the fiber and matrix and the fiber volume fraction (5 inputs, 1 output).