Nicola, I think you are hitting a periodicity issue here.
The points with angle 7/4 pi and 5/4 pi are at a distance (from pi/4) of 6/4 pi = -pi/2 (this is the shorter distance, and this is what is used in the code), and pi = -pi (this could be either -pi or pi, and it is in fact not well defined to use points at exactly T/2 distance where T is the periodicity, since either T/2 or -T/2 are the same point) from 1/4 pi. With your weights, you may get -pi/4 -pi/4 + pi/4 = - pi/4 or -pi/4 + pi/4 + pi/4 = pi/4 (which is what you observe). The only solution to this is to make sure that the initial grid does not contain a single cell, with a periodic boundary associated to the it. This produces a manifold which is not well defined, and does not behave as one would expect. L. > On 21 Jan 2020, at 16:09, Nicola Giuliani <[email protected]> wrote: > > Dear all, > > I have the following snippet of code. > > > const unsigned int dim = 2; > double factor = 1./std::sqrt(dim); > > Point<dim> p1test{factor, -factor}; > Point<dim> p2test{factor, factor}; > Point<dim> p3test{-factor, -factor}; > > std::vector<Point<dim> > surrounding_points; > surrounding_points.push_back(p1test); > surrounding_points.push_back(p2test); > surrounding_points.push_back(p3test); > > std::vector<double> surrounding_weights(3); > surrounding_weights[0] = 0.5; > surrounding_weights[1] = 0.25; > surrounding_weights[2] = 0.25; > > auto new_vertex = spherical_manifold.get_new_point( > ArrayView<Point<spacedim>>(&surrounding_points[0], > surrounding_points.size()), > ArrayView<double>(&surrounding_weights[0], > surrounding_weights.size())); > > I would expect the new point to coincide with the original one, but instead > it collapses on the second. Looking into the code of spherical manifold the > associated angles are: 7/4 pi, 1/4 pi and 5/4 pi. From this representation I > would expect the projected point to be at 5/4 pi. > > I really don't understand this behavior of SphericalManifold, do you have an > explanation? > > Bests, > Nicola > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/ca22bb00-481d-49ae-aa38-1572415d8340%40googlegroups.com. -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/60D6F4C0-98FE-486C-B216-5BFE17D20EAC%40gmail.com.
