flatten

 FLATTEN - mode-k unfolding of a tensor

 Syntax
  function Z=flatten(X,k)
 
 See also
  FLATTEN_ADJ

 Reference
 "On the extension of trace norm to tensors"
 Ryota Tomioka, Kohei Hayashi, and Hisashi Kashima
 arXiv:1010.0789
 http://arxiv.org/abs/1010.0789

 Copyright(c) 2010 Ryota Tomioka
 This software is distributed under the MIT license. See license.txt

0001 % FLATTEN - mode-k unfolding of a tensor
0002 %
0003 % Syntax
0004 %  function Z=flatten(X,k)
0005 %
0006 % See also
0007 %  FLATTEN_ADJ
0008 %
0009 % Reference
0010 % "On the extension of trace norm to tensors"
0011 % Ryota Tomioka, Kohei Hayashi, and Hisashi Kashima
0012 % arXiv:1010.0789
0013 % http://arxiv.org/abs/1010.0789
0014 %
0015 % Copyright(c) 2010 Ryota Tomioka
0016 % This software is distributed under the MIT license. See license.txt
0017 
0018 
0019 function Z=flatten(X,jj)
0020 
0021 nd=ndims(X);
0022 
0023 if jj~=1
0024   X=permute(X,[jj:nd, 1:jj-1]);
0025 end
0026 
0027 Z=X(:,:);