You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: AnisotropicTheory.m
    path of file: ./repos/mtex/doc/Elasticity
    
    the code of the file until where you have to start completion: %% Anisotropic Elasticity
%
%%
% The linear theory of ellasticity in ani
    
function
E = C.YoungsModulus

% which can be evaluated at any direction
E.eval(d)

% or plot it
setMTEXpref('defaultColorMap',blue2redColorMap);
plot(C.YoungsModulus,'complete','upper')

%% Linear Compressibility
% The linear compressibility is the deformation of an arbitrarily shaped
% specimen caused by an increase in hydrostatic pressure and can be
% described by a second rank tensor. Similar to the Young's modulus it can
% be computed by the command <stiffnessTensor.linearCompressibility.html
% linearCompressibility> for specific directions |d| or as a spherical
% function

% compute as a spherical function
beta = linearCompressibility(C)

% plot it
plot(beta,'complete','upper')

% evaluate the function at a specific direction
beta.eval(d)

%% Poisson Ratio 
% The rate of compression / decompression in a direction |n| normal to the
% pulling direction |p| is called Poisson ratio.

% the pulling direction
p = vector3d.Z;

% two orthogonal directions
n = [vector3d.X,vector3d.Y];

% the Poisson ratio
nu = C.PoissonRatio(p,n)


%%
% If we ommit in the call to <stiffnessTensor.PoissonRatio.html
% |PoissonRatio|> the last argument 

nu = C.PoissonRatio(p)

%%
% we again obtain a spherical function. However, this time it is only
% meaningful to evaluate this function at directions perpend