--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m-toolbox/classes/@ssm/blockMatAdd.m	Wed Nov 23 19:22:13 2011 +0100
@@ -0,0 +1,61 @@
+% adds corresponding matrices of same sizes or empty inside cell array
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% DESCRIPTION: blockMatAdd adds corresponding matrices of same sizes or empty inside
+% cell array
+%
+% CALL: [cell3] = ssm.blockMatAdd(cell1,cell2)
+%
+% INPUTS:
+%       cell1 - cell array of matrices representing a matrix by blocs.
+%               blocs may be empty
+%       cell2 - cell array of matrices representing a matrix by blocs.
+%               blocs may be empty
+%
+% OPTIONNAL INPUTS:
+%       isnotempty_1 - logical array tells ~isequal(cell1{ii,jj},[])
+%       isnotempty_2 - logical array tells ~isequal(cell2{ii,jj},[])
+%
+% OUTPUTS:
+%       cell3 - cell array of matrices representing a matrix by blocs.
+%               blocs may be empty
+%
+% NOTE : function is private to the ssm class
+%
+% VERSION: '$Id: blockMatAdd.m,v 1.4 2010/08/27 13:02:45 adrien Exp $'
+%
+% TO DO :
+% check ME in case of mixed symbolic and double
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+function a = blockMatAdd(varargin)
+  a=varargin{1};
+  b =varargin{2};
+  Nrow = size(a,1);
+  Ncol = size(a,2);
+  if nargin ==4
+    error('please remove the emptiness array as arguments, as they are not used anymore')
+  else
+    for ii=1:Nrow
+      for jj=1:Ncol
+        if  min(jj,Nrow)==min(ii,Ncol)
+          % if we are on the extended diagonal, matrices should be there, add!
+          try
+            a{ii,jj} = a{ii,jj} + b{ii,jj};
+          catch ME
+            a{ii,jj} = sym(a{ii,jj}) + sym(b{ii,jj});
+          end
+        elseif ~isequal(a{ii,jj}, []) && ~isequal(b{ii,jj}, [])
+          % if both matrices are non-empty
+            try
+              a{ii,jj} = a{ii,jj} + b{ii,jj};
+            catch ME
+              a{ii,jj} = sym(a{ii,jj}) + sym(b{ii,jj});
+            end
+        elseif ~isequal(b{ii,jj}, [])
+            % if only the b is not empty
+            a{ii,jj} = b{ii,jj};
+        end
+      end
+    end
+  end
+end