Added new method (center).

src/@dseries/center.m

+function o = center(o, geometric) % --*-- Unitary tests --*--
+
+% Centers @dseries object o around its mean (arithmetic or geometric).
+%
+% INPUTS
+%  o o             dseries object [mandatory].
+%  o geometric     logical [default is false], if true returns the geometric mean.
+%
+% OUTPUTS
+%  o o             o
+
+% Copyright (C) 2016 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare 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.
+%
+% Dynare 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 Dynare.  If not, see <http://www.gnu.org/licenses/>.
+
+if nargin<2
+    geometric = false;
+end
+
+if geometric
+    o = o/mean(o, true); 
+else
+    o = o-mean(o, false);
+end
+
+%@test:1
+%$ % Define a dataset.
+%$ A = repmat([1.005, 1.05], 10, 1);
+%$
+%$ % Instantiate a time series object and compute the mean.
+%$ try
+%$    ts = dseries(A);
+%$    ts.center(true);
+%$    t(1) = 1;
+%$ catch
+%$    t = 0;
+%$ end
+%$
+%$ if t(1)
+%$    t(2) = all(all(abs(ts.data-ones(10,2))<1e-12));
+%$ end
+%$ T = all(t);
+%@eof:1

src/@dseries/subsref.m

@@ -90,7 +90,7 @@ switch S(1).type
       case 'freq'
         % Returns an integer characterizing the data frequency (1, 4, 12 or 52)
         B = A.dates.freq;
-      case {'lag','lead','hptrend','hpcycle','chain','detrend','exist','mean','std'} % Methods with less than two arguments.
+      case {'lag','lead','hptrend','hpcycle','chain','detrend','exist','mean','std','center'} % Methods with less than two arguments.
         if length(S)>1 && isequal(S(2).type,'()')
             if isempty(S(2).subs)
                 B = feval(S(1).subs,A);