Added comment.

src/@dates/double.m

@@ -30,6 +30,7 @@ function [m, f]  = double(o) % --*-- Unitary tests --*--
 
 if o.freq==365
     error('This method is not implemented for daily frequency.')
+    % Would need to find a way to deal with leap years
 end
 
 m = o.time(:,1)+(o.time(:,2)-1)/o.freq;