are the vectors in decomposition
L = [1; -1]; %the weights (should be a column vector of length r)
S = symktensor(L, X, m) %Declare a symktensor object

%% 
% A |symktensor| object can be declared without a weight vector by
% specifiying the number of modes, the rank, and an additional 'nolambda' 
% option. In this case, the lambda vector is set to a vector of all ones.
S2 = symktensor(X, m, r, true)
%%
% A random |symktensor| object can be declared by passing the
% constructor two arguments: the rank of th