diff --git a/matlab/@dates/dates.m b/matlab/@dates/dates.m
index 99093bfe7..5cb9a7318 100644
--- a/matlab/@dates/dates.m
+++ b/matlab/@dates/dates.m
@@ -45,7 +45,7 @@ function dd = dates(varargin) % --*-- Unitary tests --*--
 %! @end deftypefn
 %@eod:
 
-% Copyright (C) 2011-2013 Dynare Team
+% Copyright (C) 2011-2014 Dynare Team
 %
 % This file is part of Dynare.
 %
@@ -62,6 +62,7 @@ function dd = dates(varargin) % --*-- Unitary tests --*--
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
+% Initialization.
 if nargin>0 && ischar(varargin{1}) && isequal(varargin{1},'initialize')
     dd = struct('ndat', 0, 'freq', NaN(0), 'time', NaN(0,2));
     dd = class(dd,'dates');
@@ -71,61 +72,98 @@ end
 
 dd = evalin('base','emptydatesobject');
 
-switch nargin
-  case 0
-    % Returns an empty object
+if isequal(nargin, 0)
+    % Return an empty dates obect
     return
-  case 1
-    if isa(varargin{1},'dates')
-        % Returns a copy of the input argument
-        dd = varargin{1};
-    elseif isdate(varargin{1})
-        date = string2date(varargin{1});
-        dd.ndat = 1;
-        dd.freq = date.freq;
-        dd.time = date.time;
-    elseif isfreq(varargin{1})
-        % Instantiate an empty dates object (only set frequency)
-        if ischar(varargin{1})
-            dd.freq = string2freq(varargin{1});
-        else
-            dd.freq = varargin{1};
-        end
+end
+
+if all(cellfun(@isdates, varargin))
+    % Concatenates dates in a dates object.
+    dd = horzcat(varargin{:});
+    return
+end
+
+if all(cellfun(@isstringdate,varargin))
+    % Concatenates dates in a dates object.
+    tmp = cellfun(@string2date,varargin);
+    if all([tmp.freq]-tmp(1).freq==0)
+        dd.freq = tmp(1).freq;
     else
-        error('dates:: Wrong calling sequence of the constructor!')
+        error('dates::dates: Wrong calling sequence of the constructor! All dates must have common frequency.')
     end
-  otherwise
-    if isdate(varargin{1})
-        dd.ndat = nargin;
-        dd.time = NaN(dd.ndat,2);
-        date = string2date(varargin{1});
-        dd.freq = date.freq;
-        dd.time(1,:) = date.time;
-    elseif isdates(varargin{1})
-        dd = horzcat(varargin{:});
-        return
-    elseif isfreq(varargin{1})
-        S.type = '()';
-        S.subs = varargin;
-        dd = subsref(dd,S);
-        return
+    dd.ndat = length(tmp);
+    dd.time = transpose(reshape([tmp.time],2,dd.ndat));
+    return
+end
+
+if isequal(nargin,1) && isfreq(varargin{1})
+    % Instantiate an empty dates object (only set frequency)
+    if ischar(varargin{1})
+        dd.freq = string2freq(varargin{1});
     else
-        error('dates::dates: Wrong calling sequence!')
+        dd.freq = varargin{1};
     end
-    for i=2:dd.ndat
-        if isdate(varargin{i})
-            date = string2date(varargin{i});
-            if isequal(date.freq,dd.freq)
-                dd.time(i,:) = date.time;
+    return
+end
+
+if isequal(nargin,3) && isfreq(varargin{1})
+    if ischar(varargin{1})
+        dd.freq = string2freq(varargin{1});
+    else
+        dd.freq = varargin{1};
+    end
+    if (isnumeric(varargin{2}) && isvector(varargin{2}) && isint(varargin{2}))
+        if isnumeric(varargin{3}) && isvector(varargin{3}) && isint(varargin{3})
+            if all(varargin{3}>=1) && all(varargin{3}<=dd.freq)
+                dd.time = [varargin{2}(:), varargin{3}(:)];
+                dd.ndat = size(dd.time,1);
             else
-                 error(sprintf('dates::dates: Check that all the inputs have the same frequency (see input number %i)!',i))
+                error(sprintf('dates::dates: Wrong calling sequence of the constructor! Third input must contain integers between 1 and %i.',dd.freq))
             end
         else
-            error(sprintf('dates::dates: Input %i has to be a string date!',i))
+            error('dates::dates: Wrong calling sequence of the constructor! Third input must be a vector of integers.')
+        end
+    else
+        error('dates::dates: Wrong calling sequence of the constructor! Second input must be a vector of integers.')
+    end
+    return
+end
+
+if isequal(nargin,2) && isfreq(varargin{1})
+    if ischar(varargin{1})
+        dd.freq = string2freq(varargin{1});
+    else
+        dd.freq = varargin{1};
+    end
+    if isequal(dd.freq, 1)
+        if (isnumeric(varargin{2}) && isvector(varargin{2}) && isint(varargin{2}))
+            dd.time = [varargin{2}, ones(length(varargin{2},1))];
+            dd.ndat = size(dd.time,1);
+            return
+        else
+            error('dates::dates: Wrong calling sequence of the constructor! Second input must be a vector of integers.')
+        end
+    else
+        if isequal(size(varargin{2},2), 2)
+            if all(isint(varargin{2}(:,1))) && all(isint(varargin{2}(:,1)))
+                if all(varargin{2}(:,2)>=1) && all(varargin{2}(:,2)<=dd.freq)
+                    dd.time = [varargin{2}(:,1), varargin{2}(:,2)];
+                    dd.ndat = size(dd.time,1);
+                else
+                    error(sprintf('dates::dates: Wrong calling sequence of the constructor! Second column of the last input must contain integers between 1 and %i.',dd.freq))
+                end
+            else
+                error('dates::dates: Wrong calling sequence! Second input argument must be an array of integers.')
+            end
+        else
+            error('dates::dates: Wrong calling sequence!')
         end
     end
+    return
 end
 
+error('dates::dates: Wrong calling sequence!')
+
 %@test:1
 %$ % Define some dates
 %$ B1 = '1945Q3';
diff --git a/matlab/utilities/dates/isdate.m b/matlab/utilities/dates/isdate.m
index 67bfcdb2d..726e5e479 100644
--- a/matlab/utilities/dates/isdate.m
+++ b/matlab/utilities/dates/isdate.m
@@ -30,11 +30,11 @@ if isnumeric(str) && isscalar(str)
     return
 end
 
-b = isquaterly(str) || isyearly(str) || ismonthly(str) || isweekly(str);
+b = isstringdate(str);
 
 %@test:1
 %$
-%$ date_1 = '1950M2';
+%$ date_1 = 1950;
 %$ date_2 = '1950m2';
 %$ date_3 = '-1950m2';
 %$ date_4 = '1950m52';
diff --git a/matlab/utilities/dates/isstringdate.m b/matlab/utilities/dates/isstringdate.m
new file mode 100644
index 000000000..fbac8b007
--- /dev/null
+++ b/matlab/utilities/dates/isstringdate.m
@@ -0,0 +1,54 @@
+function b = isstringdate(str)  % --*-- Unitary tests --*--
+
+% Tests if the input string can be interpreted as a date.
+%
+% INPUTS 
+%  o str     string.
+%
+% OUTPUTS 
+%  o b       integer scalar, equal to 1 if str can be interpreted as a date or 0 otherwise.
+
+% Copyright (C) 2013 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 ischar(str)
+    b = isquaterly(str) || isyearly(str) || ismonthly(str) || isweekly(str);
+else
+    b = 0;
+end
+
+%@test:1
+%$
+%$ date_1 = '1950M2';
+%$ date_2 = '1950m2';
+%$ date_3 = '-1950m2';
+%$ date_4 = '1950m52';
+%$ date_5 = ' 1950';
+%$ date_6 = '1950Y';
+%$ date_7 = '-1950a';
+%$ date_8 = '1950m ';
+%$
+%$ t(1) = dyn_assert(isstringdate(date_1),1);
+%$ t(2) = dyn_assert(isstringdate(date_2),1);
+%$ t(3) = dyn_assert(isstringdate(date_3),1);
+%$ t(4) = dyn_assert(isstringdate(date_4),0);
+%$ t(5) = dyn_assert(isstringdate(date_5),0);
+%$ t(6) = dyn_assert(isstringdate(date_6),1);
+%$ t(7) = dyn_assert(isstringdate(date_7),1);
+%$ t(8) = dyn_assert(isstringdate(date_8),0);
+%$ T = all(t);
+%@eof:1
\ No newline at end of file