--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extra/control-devel/devel/iddata_merge.m	Sun Mar 04 22:17:45 2012 +0000
@@ -0,0 +1,14 @@
+%u = iddata ({(1:10).', (21:30).'}, {(41:50).', (61:70).'});
+%v = iddata ({(11:20).', (31:40).'}, {(51:60).', (71:80).'});
+
+oy = ones (200, 5);
+ou = ones (200, 4);
+y = repmat ({oy}, 6, 1);
+u = repmat ({ou}, 6, 1);
+
+u = iddata (y, u)
+v = u
+
+a = [u, v]
+b = [u; v]
+c = merge (u, v)
\ No newline at end of file

--- a/extra/control-devel/inst/@iddata/cat.m	Sun Mar 04 17:35:42 2012 +0000
+++ b/extra/control-devel/inst/@iddata/cat.m	Sun Mar 04 22:17:45 2012 +0000
@@ -26,39 +26,25 @@
 
 function dat = cat (dim, varargin)
 
+  tmp = cellfun (@iddata, varargin);
+
   switch (dim)
-    case 1      # add samples; p, m, e identical
-      %[~, p, m, e]
-      %nvec = cellfun (@size
-      %[~, p, m, e] = cellfun (@size, varargin, "uniformoutput", false)
-      
-      %y = cellfun (@(dat) vertcat (dat.y) 
-      %dat = cellfun (@iddata, varargin)
-      #y = cellfun (@vertcat
-      
-      #ycell = cellfun (@(dat) dat.y, varargin, "uniformoutput", false)
-
-      tmp = cellfun (@iddata, varargin);
+    case 1      # vertcat - catenate samples
       y = cellfun (@vertcat, tmp.y, "uniformoutput", false);
       u = cellfun (@vertcat, tmp.u, "uniformoutput", false);
-      
-      dat = iddata (y, u);
-
-      %varargin{:}.y
-      %varargin(:).y
-    case 2      # horzcat, same outputs; 
     
-    case 3      # vertcat, same inputs
+    case 2      # horzcat - catenate channels;
+      y = cellfun (@horzcat, tmp.y, "uniformoutput", false);
+      u = cellfun (@horzcat, tmp.u, "uniformoutput", false);
     
-    case 4      # add experiments
-      tmp = cellfun (@iddata, varargin);
-      
+    case 3      # merge - catenate experiments
       y = vertcat (tmp.y);
       u = vertcat (tmp.u);
-      
-      dat = iddata (y, u);
-      
+    
+    otherwise
+      error ("iddata: cat: '%s' is an invalid dimension", num2str (dim));
+  endswitch
   
-  endswitch
+  dat = iddata (y, u);
 
 endfunction
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extra/control-devel/inst/@iddata/diff.m	Sun Mar 04 22:17:45 2012 +0000
@@ -0,0 +1,32 @@
+## Copyright (C) 2012   Lukas F. Reichlin
+##
+## This file is part of LTI Syncope.
+##
+## LTI Syncope is free software: you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## LTI Syncope is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with LTI Syncope.  If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{dat} =} cat (@var{dim}, @var{dat1}, @var{dat2}, @dots{})
+## Concatenation of iddata objects along dimension @var{dim}.
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: March 2012
+## Version: 0.1
+
+function dat = diff (dat, k)
+
+  dat.y = cellfun (@(y) diff (y, k), dat.y, "uniformoutput", false);
+  dat.u = cellfun (@(u) diff (u, k), dat.u, "uniformoutput", false);
+
+endfunction
\ No newline at end of file