Added conversion routines for dates.

Conversion of daily dates objects to lower frequency.

src/utilities/convert/dates2M.m

+function m = dates2M(d)
+
+% INPUTS
+% - d   [dates]    daily frequency object with n elements.
+%
+% OUTPUTS
+% - m   [dates]    monthly frequency object with n elements (with repetitions).
+
+% Copyright © 2020 Dynare Team
+%
+% This code 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 dates submodule 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/>.
+
+time = datevec(d.time(:,1));
+m = dates(12, time(:,1:2));
\ No newline at end of file

src/utilities/convert/dates2Q.m

+function m = dates2Q(d)
+
+% INPUTS
+% - d   [dates]    daily frequency object with n elements.
+%
+% OUTPUTS
+% - q   [dates]    quaterly frequency object with n elements (with repetitions).
+
+% Copyright © 2020 Dynare Team
+%
+% This code 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 dates submodule 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/>.
+
+time = datevec(d.time(:,1));
+time = time(:,1:2);
+
+isq1 = arrayfun( @(m) ismember(m, [1, 2, 3]), time(:,2));
+isq2 = arrayfun( @(m) ismember(m, [4, 5, 6]), time(:,2));
+isq3 = arrayfun( @(m) ismember(m, [7, 8, 9]), time(:,2));
+isq4 = arrayfun( @(m) ismember(m, [10, 11, 12]), time(:,2));
+
+time(isq1,2) = 1;
+time(isq2,2) = 2;
+time(isq3,2) = 3;
+time(isq4,2) = 4;
+
+m = dates(4, time(:,1:2));
\ No newline at end of file

src/utilities/convert/dates2Y.m

+function y = dates2Y(d)
+
+% INPUTS
+% - d   [dates]    daily frequency object with n elements.
+%
+% OUTPUTS
+% - y   [dates]    annual frequency object with n elements (with repetitions).
+
+% Copyright © 2020 Dynare Team
+%
+% This code 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 dates submodule 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/>.
+
+time = datevec(d.time(:,1));
+y = dates(1, time(:,1));
\ No newline at end of file