diff --git a/matlab/check_prior_analysis_data.m b/matlab/check_prior_analysis_data.m
new file mode 100644
index 000000000..6b4dbdcbd
--- /dev/null
+++ b/matlab/check_prior_analysis_data.m
@@ -0,0 +1,97 @@
+function [info,description] = check_prior_analysis_data(type,M_)
+% Copyright (C) 2009 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/>.
+    
+    info = 0;
+    if nargout>1
+        description = '';
+    end
+    
+    %% Get informations about prior draws files. 
+    if ~exist([ M_.dname '/prior/draws'],'dir')
+        disp('check_prior_analysis_data:: Can''t find any prior draws file!')
+        return
+    end
+    prior_draws_info = dir([ M_.dname '/prior/draws/prior_draws*.mat']);
+    name_of_the_last_prior_draw_file = prior_draws_info(end).name ;%mhname
+    date_of_the_last_prior_draw_file = prior_draws_info(end).datenum ;%mhdate
+    
+    %% Get informations about _posterior_draws files.
+    if isempty(prior_draws_info)
+        info = 1;
+        if nargout>1
+            description = 'prior_sampler has to be called.';
+        end
+        return
+    else
+        number_of_last_prior_draws_file = length(prior_draws_info);
+        date_of_the_prior_definition = get_date_of_a_file([ M_.dname '/prior/definition.mat']);
+        if date_of_the_prior_definition>date_of_the_last_prior_draw_file
+            info = 2;
+            if nargout>1
+                description = 'prior draws files have to be updated.';
+            end
+            return
+        else
+            info = 3; % Nothing to do!  
+            if nargout>1
+                description = 'prior draws files are up to date.';
+            end
+        end
+    end
+    
+    %% Get informations about prior data files.
+    switch type
+      case 'variance'
+        generic_prior_data_file_name = 'Prior2ndOrderMoments';
+      case 'decomposition'
+        generic_prior_data_file_name = 'PriorVarianceDecomposition';
+      case 'correlation'
+        generic_prior_data_file_name = 'PriorCorrelations';
+      case 'conditional decomposition'
+        generic_prior_data_file_name = 'PriorConditionalVarianceDecomposition';
+      otherwise
+        disp(['This feature is not yet implemented!')
+    end
+    CheckPath('prior/moments')
+    pdfinfo = dir([ M_.dname '/prior/' generic_prior_data_file_name '*']);
+    if isempty(pdfinfo)
+        info = 4;
+        if nargout>1
+            description = 'prior draws files have to be processed.';
+        end
+        return
+    else
+        number_of_the_last_prior_data_file = length(pdfinfo);
+        name_of_the_last_prior_data_file = pdinfo(end).name;
+        pdfdate = pdinfo(end).datenum;
+        % /!\ REMARK /!\
+        % The user can change the model or the value of a calibrated 
+        % parameter without changing the prior. In this case the (prior) 
+        % moments should be computed. But this case cannot be detected!!! 
+        if pdfdate<date_of_the_last_prior_draw_file
+            info = 5; % prior data files have to be updated.
+            if nargout>1
+                description = 'prior data files have to be updated.';
+            end
+        else
+            info = 6; % Ok (nothing to do ;-)
+            if nargout>1
+                description = 'prior data files are up to date.';
+            end
+        end
+    end
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