Note that the only essential addition is the line marked with
asterisks. It is worth pointing out one other thing here, though: because we
detach the manifold description from the surface mesh, whenever we use a
-mapping object in the rest of the program, it has no curves boundary
+mapping object in the rest of the program, it has no curved boundary
description to go on any more. Rather, it will have to use the implicit,
FlatManifold class that is used on all parts of the domain not
explicitly assigned a different manifold object. Consequently, whether we use
MappingQ(2), MappingQ(15) or MappingQ1, each cell of our mesh will be mapped
-using a bilinear approximation.
+using a bilinear approximation. (That is of course undesirable, and can be
+fixed by creating a manifold description of the domain you have, and attaching
+this manifold to the triangulation.)
All these drawbacks aside, the resulting pictures are still pretty. The only
other differences to what's in step-38 is that we changed the right hand side