and weights of a symmetric
% Kruskal tensor decomposition. The vectors in the decomposition are 
% collected as the columns of a matrix |X|, referred to as the factor matrix.
% The lambda vector, containing the (often optional) weights is input into the 
% constructor as a column vector. The lambda vector and factor matrix are 
% collectively referred to as the constituent parts in the declaration of a
% |symktensor|. For example, consider the decomposition of a tensor 
% $\mathcal{A}$. 
%
% $$\mathcal{A} =