* in each time step, it is necessary that we also project the boundary
* values of the initial values, before projecting them to the whole domain.
*
+ * Obviously, the results of the two schemes for projection are different.
+ * Usually, when projecting to the boundary first, the $L_2$-norm of the
+ * difference between original function and projection over the whole domain
+ * will be larger (factors of five have been observed) while the $L_2$-norm
+ * of the error integrated over the boundary should of course be less. The
+ * reverse should also hold if no projection to the boundary is performed.
+ *
* The selection whether the projection to the boundary first is needed is
* done with the #project_to_boundary_first# flag passed to the function.
* If #false# is given, the additional quadrature formula for faces is
* ignored.
*
- * You should be aware of the fact that if no projection is to the boundary
+ * You should be aware of the fact that if no projection to the boundary
* is requested, a function with zero boundary values may not have zero
* boundary values after projection. There is a flag for this especially
* important case, which tells the function to enforce zero boundary values