diff --git a/src/utilities/misc/dummy.m b/src/utilities/misc/dummy.m
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+++ b/src/utilities/misc/dummy.m
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+function o = dummy(iperiod, len, subperiod, name)  % --*-- Unitary tests --*--
+
+% Returns a dummy in a dseries object.
+%
+% INPUTS
+% - iperiod     [dates]     scalar, initial period.
+% - len         [integer]   scalar, number of periods.
+% - superiod    [integer]   scalar or vector, subperiod(s) index where the dummy is nonzero.
+% - name        [char]      row char array, name of the dummy variable.
+%
+% OUTPUTS
+% - o           [dseries]
+
+% Copyright © 2022 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 <https://www.gnu.org/licenses/>.
+
+if ~(isdate(iperiod) || isdates(iperiod))
+    error('First input argument must be a string date or dates object.')
+end
+
+if ~(isscalar(len) && isint(len))
+    error('Second input argument must be a scalar integer.')
+end
+
+if ~((isscalar(subperiod) || isvector(subperiod)) && all(isint(subperiod)))
+    error('Second input argument must be a scalar integer.')
+else
+    if ~issubperiod(subperiod, dates(iperiod).freq)
+        error('Third input argument is not a subperiod.')
+    end
+end
+
+p = dates(iperiod)+(0:len-1);
+d = zeros(len, 1);
+
+for i=1:length(subperiod)
+    d(p.subperiod()==subperiod(i)) = 1;
+end
+
+o = dseries(d, iperiod, name);
+
+return
+
+%@test:1
+try
+    ts = dummy(dates('1950Q1'), 15, 2, 'toto');
+    t(1) = true;
+catch
+    t(1) = false;
+end
+
+if t(1)
+    t(2) = all(ts(ts.dates.subperiod()==2).data);
+end
+
+T = all(t);
+%@eof:1
+
+%@test:2
+try
+    ts = dummy('1950Q1', 15, 2, 'toto');
+    t(1) = true;
+catch
+    t(1) = false;
+end
+
+if t(1)
+    t(2) = all(ts(ts.dates.subperiod()==2).data);
+end
+
+T = all(t);
+%@eof:2
+
+%@test:3
+try
+    ts = dummy('1950Q1', 15, [1,2,3,4], 'toto');
+    t(1) = true;
+catch
+    t(1) = false;
+end
+
+if t(1)
+    t(2) = all(ts.data);
+end
+
+T = all(t);
+%@eof:3
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