--- a
+++ b/@dataframe/minus.m
@@ -0,0 +1,66 @@
+function resu = minus(A, B);
+
+  %# function resu = minus(A, B)
+  %# Implements the '-' operator when at least one one argument is a dataframe.
+
+  %% Copyright (C) 2009-2010 Pascal Dupuis <Pascal.Dupuis@uclouvain.be>
+  %%
+  %% This file is part of Octave.
+  %%
+  %% Octave 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 2, or (at your option) any later version.
+  %%
+  %% Octave 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 Octave; see the file COPYING.  If not,
+  %% write to the Free Software Foundation, 59 Temple Place -
+  %% Suite 330, Boston, MA 02111-1307, USA.
+  
+  %#
+  %# $Id: minus.m 852 2010-07-22 10:47:55Z dupuis $
+  %#
+
+  [A, B] = df_basecomp(A, B);
+
+  if isscalar(A) 
+    %# B is a dataframe
+    resu = B; 
+    for indi = 1:B._cnt(2),
+      resu._data{indi} = A-B._data{indi};
+    endfor
+    return
+  elseif ismatrix(A),
+    resu = B; 
+    for indi = 1:B._cnt(2),
+      resu._data{indi} = A(indi, :) - B._data{indi};
+    endfor
+    return
+  endif
+
+  if isscalar(B),
+    resu = A; 
+    for indi = 1:A._cnt(2),
+      resu._data{indi} = A._data{indi} -B;
+    endfor
+    return
+  elseif ismatrix(B),
+    resu = A; 
+    for indi = 1:A._cnt(2),
+      resu._data{indi} = A._data{indi} -B(:, indi);
+    endfor
+    return
+  endif
+
+  resu = A; 
+  for indi = 1:A._cnt(2),
+    resu._data{indi} = A._data{indi} -B._data{indi};
+  endfor
+  
+endfunction