* @p{dof2} need to be @ref{DoFHandler}
* based on the same triangulation.
*
- * This function is interesting for
- * e.g. extrapolating patchwise a
- * piecewise linear dual solution
- * to a piecewise quadratic dual
- * solution.
+ * This function is interesting
+ * for e.g. extrapolating
+ * patchwise a piecewise linear
+ * solution to a piecewise
+ * quadratic solution.
+ *
+ * Note that the resulting field
+ * does not satisfy continuity
+ * requirements of the given
+ * finite elements. You have to
+ * apply
+ * @ref{ConstraintMatrix}@p{::distribute}
+ * with the hanging node
+ * constraints of the second DoF
+ * handler object to make the
+ * output continuous again.
*/
template <int dim, typename number>
static void extrapolate(const DoFHandler<dim> &dof1,
- const Vector<number> &z1,
+ const Vector<number> &z1,
const DoFHandler<dim> &dof2,
- Vector<number> &z2);
+ Vector<number> &z2);
/**