--- a/src/Expression.cc	Sun Sep 01 22:47:21 2013 +0200
+++ b/src/Expression.cc	Sun Sep 01 23:14:28 2013 +0200
@@ -49,11 +49,16 @@
 
       if (!error_state)
         {
+          std::cout << "Creating expression..."<< std::endl;
           octave_value_list b (3, 1);
           octave_value_list tmp = feval (fh->function_value (), b);
           Array<double> res = tmp(0).array_value ();
           std::size_t l = res.length ();
 
+          /*
+          Look at the discussion 
+          http://fenicsproject.org/qa/781/scalar-and-vector-valued-expression
+          */
           if (l > 1)
             retval = new coefficient (str, *fh, l);
           else

--- a/src/Function.cc	Sun Sep 01 22:47:21 2013 +0200
+++ b/src/Function.cc	Sun Sep 01 23:14:28 2013 +0200
@@ -4,8 +4,11 @@
 
 DEFUN_DLD (Function, args, , "-*- texinfo -*-\n\
 @deftypefn {Function File} {[@var{func}]} = \
-fem_func (@var{name}, @var{Functional Space}, @var{Vector})\n\
-The input parameters are\n\
+Function (@var{name}, @var{Functional Space} or @var{Function},\
+@var{Vector} or @var{index})\n\
+These function can be used in two ways\n\
+@itemize @bullet \n\
+@item To create a function from a vector. In this case, the arguments are:\n\
 @itemize @bullet \n\
 @item @var{name} is a string representing the name of the function\n\
 @item @var{Functional Space} is the fem-fenics functional space where\
@@ -13,6 +16,14 @@
 @item @var{Vector} contains the value of the coefficients\
 for the basis functions of @var{Functional Space}\n\
 @end itemize\n\
+@item To extract a scalar field from a vectorial one\n\
+@itemize @bullet \n\
+@item @var{name} is a string representing the name of the function\n\
+@item @var{Function} is the vector valued Function\n\
+@item @var{Index} contains the index of the scalar field to extract.\
+Index starts from 1. \n\
+@end itemize\n\
+@end itemize \n\
 The output @var{func} is an object which contain a representation of the\
 function @var{Vector} which can be plotted or saved.\n\
 @seealso{fem_plot, fem_save}\n\
@@ -20,7 +31,7 @@
 {
 
   int nargin = args.length ();
-  octave_value retval=0;
+  octave_value retval;
   
   if (nargin < 3 || nargin > 3)
     print_usage ();
@@ -55,6 +66,7 @@
                 error ("The size of the functional space and of the vector must agree");
               else
                 {
+                  std::cout <<"creating function from vector..."<< std::endl;
                   dolfin::Vector du(myu.length ());
                   for (std::size_t i = 0; i < myu.length (); ++i)
                     du.setitem (i, myu(i));
@@ -78,11 +90,17 @@
               const boost::shared_ptr<const dolfin::Function> & f = fspo.get_pfun ();
 
               if (f->value_rank () < 1)
-                error ("The function you provided isn't a vecotr field");
+                error ("Function: The function you provided isn't a vecotr field");
               else
                 {
-                  boost::shared_ptr <const dolfin::Function> u (new dolfin::Function((*f)[idx]));
-                  retval = new function (str, u);
+                  std::cout <<"Extracting function..."<< std::endl;
+                  if (idx < 1 || idx > f->value_dimension (0))
+                    error ("Function: index out of bounds");
+                 else
+                   {
+                      boost::shared_ptr <const dolfin::Function> u (new dolfin::Function((*f)[idx - 1]));
+                      retval = new function (str, u);
+                   }
                 }
             }
         }