Added second input argument to missing/nanmean routine.

This additional argument is optional and can be used to specify along which
dimension the mean has to be computed.

Fixes the bug introduced in b4204f8b for those
who do not have the statistics toolbox.

matlab/missing/nanmean/nanmean.m

-function y = nanmean(x)
-% Computes the mean of each column of a matrix with some NaNs.
+function y = nanmean(x, dim)
 
-%@info:
-%! @deftypefn {Function File} {@var{y} =} nanmean (@var{x})
-%! @anchor{nanmean}
-%! @sp 1
-%! Computes the mean of each column of a matrix with some NaNs.
-%! @sp 2
-%! @strong{Inputs}
-%! @table @ @var
-%! @item x
-%! Matlab matrix (T-by-N).
-%! @end table
-%! @sp 2
-%! @strong{Outputs}
-%! @table @ @var
-%! @item y
-%! Matlab vector (1-by-N), the mean.
-%! @end table
-%! @sp 2
-%! @strong{This function is called by:}
-%! @sp 1
-%! @ref{compute_cova}, @ref{compute_acov}, @ref{compute_std}, @ref{nandemean}
-%! @sp 2
-%! @strong{This function calls:}
-%! @sp 1
-%! @ref{ndim}
-%!
-%! @end deftypefn
-%@eod:
+% Returns the mean of a matrix with some NaNs.
+%
+% INPUTS
+% - x      [double]    m*n matrix
+% - dim    [integer]   scalar, dimension along which the mean has to be computed.
+%
+% OUTPUTS
+% - y      [double]    1*n vector (if dim=1) or m*1 vector (if dim=2).
+%
+% REMARKS
+% (1) Default value for dim is the first non singleton dimension.
+% (2) Works with vector and matrices, not implemented for arrays with more
+% than two dimensions.
 
-% Copyright (C) 2011 Dynare Team
+% Copyright (C) 2011-2018 Dynare Team
 %
 % This file is part of Dynare.
 %
@@ -47,16 +31,39 @@ function y = nanmean(x)
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-% AUTHOR(S) stephane DOT adjemian AT univ DASH lemans DOT fr
+if nargin<2
+    % By default dim is the first non singleton dimension
+    nonsingletondims = find(find(size(x)>1));
+    if ~isempty(nonsingletondims)
+        dim = nonsingletondims(1);
+    else
+        dim = NaN;
+    end
+end
 
-switch ndim(x)
+switch ndims(x)
   case 1
-    y = mean(x(find(~isnan(x))));
+    if isnan(dim)
+        y = x;
+    else
+        y = mean(x(find(~isnan(x))), dim);
+    end
   case 2
-    y = NaN(1,size(x,2));
-    for i = 1:size(x,2)
-        y(i) = mean(x(find(~isnan(x(:,i))),i));
+    if isnan(dim)
+        y = x;
+    else
+        if isequal(dim, 1)
+            y = NaN(1, size(x, 2));
+            for i = 1:size(x, 2)
+                y(i) = mean(x(find(~isnan(x(:,i))),i));
+            end
+        else
+            y = NaN(size(x, 1), 1);
+            for i = 1:size(x, 1)
+                y(i) = mean(x(i, find(~isnan(x(i,:)))));
+            end
+        end
     end
   otherwise
-    error('descriptive_statistics::nanmean:: This function is not implemented for arrays with dimension greater than two!')
+    error('This function is not implemented for arrays with dimension greater than two!')
 end
\ No newline at end of file