added comments

generateTensorTrain.m

@@ -1,5 +1,22 @@
 function [X, G, S, V] = generateTensorTrain(N, D)
-%% GENERATETENSORTRAIN generates a tensor train with 
+% GENERATETENSORTRAIN generates a tensor with length(N) modes, where there
+% are N(i) observations in the i^th mode. The underlying tensor train has
+% latent dimension D, with D(1)=D(end)=1.
+% INPUT: 
+%   N       vector with observations in each mode
+%   D       vector specifying the size of the latent dimension,
+%           D(1)=D(end)=1 and length(D) = length(N)+1
+%
+% OUTPUT:
+%   X       A tensor with size N generated by the tensor train
+%   G       A cell array with the tensor train carts size(G{i}) =
+%           [D(i),N(i),D(i+1)]. Note G{end} = S*V'.
+%   S       A diagonal matrix (D(end-1) x D(end-1)) with the scale of each
+%           of the D(end-1) components.
+%   V       An orthogonal matrix (N(end) x D(end-1)) for the last train cart
+%
+% 
+
     G=cell(length(N),1);
     for d = 1:length(N)-1
         G{d} = randn(D(d),N(d),D(d+1));