Re: [deal.II] query FE support point type and additional info?
You can't. There is no obvious relationship between the two for *generalized* support points. There may be more, or fewer generalized support points than DoFs on a cell. Of course there is no obvious relationship but I would assume that there is some relationship between them (not necessarily unique in any direction). I guess you are saying is that we are currently not exposing any relationship between them. It's all essentially internal to the FE classes. The FE class exports where it likes stuff to be evaluated (these are the generalized support points) but how it uses the resulting vector of values to obtain DoF values is up to the internals of the FE class again. The two places (the description of where the generalized support points are, and the place that converts function values at generalized support points to DoF values) just need to agree on the order of points. But because both of these are in the same class, they may choose any perturbation of points. A FE may also describe more support point that it then decides to not use. There really is not required relationship between the two. In other words, it's up to every FE to decide what it wants things to be. Some FEs may have more generalized support points than DoFs, others less. The reason I am asking is that I would like to differentiate between a generalized support point in the interior of the cell that just happens to be on a face and a face dof (for example FE_DGQ vs FE_Q). This question does not make sense. If you have a modal (as opposed to nodal) element, then *all* generalized support points will be used in determining *each* modal DoF value. You cannot say that some generalized support points are associated with specific DoFs. get_associated_geometry_primitive answers this for DoFs, but it looks like I am out of luck tying this back to support point locations unless I have n_dofs_per_cell unit_support_points and no generalized_support_points. So I can do this for FE_DGQ but not for Nedelec or other elements. Does that sound about right? I was hoping there is an easy way to query this information. Yes, this is correct. No easy way -- in fact: no way, period -- because there is no relationship. 3. Elements like FE_QLegendre return 0 generalized support points. Is there any information I can extract from the FE about the degrees of freedom or support points in this case? I should say that the fact that FE_QLegendre doesn't publish GSPs is functionality that is missing, not because it can't define them. It's just that nobody has implemented this so far. Best W> -- Wolfgang Bangerth email: bange...@colostate.edu www: http://www.math.colostate.edu/~bangerth/ -- 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [deal.II] query FE support point type and additional info?
thanks, Wolfgang. >> 1. How can I translate between generalized_support_point j and >> dof_per_cell index k? For example FE_DGRaviartThomas<2>(1) has 9 >> generalized_support_points but 12 dofs_per_cell. > > You can't. There is no obvious relationship between the two for > *generalized* support points. There may be more, or fewer generalized > support points than DoFs on a cell. Of course there is no obvious relationship but I would assume that there is some relationship between them (not necessarily unique in any direction). I guess you are saying is that we are currently not exposing any relationship between them. The reason I am asking is that I would like to differentiate between a generalized support point in the interior of the cell that just happens to be on a face and a face dof (for example FE_DGQ vs FE_Q). get_associated_geometry_primitive answers this for DoFs, but it looks like I am out of luck tying this back to support point locations unless I have n_dofs_per_cell unit_support_points and no generalized_support_points. So I can do this for FE_DGQ but not for Nedelec or other elements. Does that sound about right? I was hoping there is an easy way to query this information. >> 3. Elements like FE_QLegendre return 0 generalized support points. Is >> there any information I can extract from the FE about the degrees of >> freedom or support points in this case? > > Nope :-) That's generally true for all elements that don't have (regular) > support points: they're not interpolatory, and so may define their shape > functions in whatever way they choose. I found get_associated_geometry_primitive(dof_idx), which tells us at least something about the shape functions. I can also check if the functions are primitive or not, but that seems to be it. -- 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [deal.II] query FE support point type and additional info?
I am looking for ways to get more information about (generalized) support points for a particular FE: 1. How can I translate between generalized_support_point j and dof_per_cell index k? For example FE_DGRaviartThomas<2>(1) has 9 generalized_support_points but 12 dofs_per_cell. You can't. There is no obvious relationship between the two for *generalized* support points. There may be more, or fewer generalized support points than DoFs on a cell. 2. https://urldefense.proofpoint.com/v2/url?u=http-3A__www.dealii.org_developer_doxygen_deal.II_DEALGlossary.html-23GlossGeneralizedSupport=DwIBaQ=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw=noUPzp6HQo5Ab1sMhXHEPDtKWiunYMqmACzbvcvljEk=xGxO7IMz8sGBENTwwyRKlCiJ7WNuI0hby0Co0ZQhaks= says FE_Q_Hierarchical has no generalized support points but the element actually returns 4 generalized support points in 2d with degree 1. Who is right? The code. We further generalized generalized support points a while back, see https://github.com/dealii/dealii/issues/4992 The glossary entry needs to be updated. 3. Elements like FE_QLegendre return 0 generalized support points. Is there any information I can extract from the FE about the degrees of freedom or support points in this case? Nope :-) That's generally true for all elements that don't have (regular) support points: they're not interpolatory, and so may define their shape functions in whatever way they choose. Best W. -- Wolfgang Bangerth email: bange...@colostate.edu www: http://www.math.colostate.edu/~bangerth/ -- 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[deal.II] query FE support point type and additional info?
Hey all, I am looking for ways to get more information about (generalized) support points for a particular FE: 1. How can I translate between generalized_support_point j and dof_per_cell index k? For example FE_DGRaviartThomas<2>(1) has 9 generalized_support_points but 12 dofs_per_cell. 2. https://urldefense.proofpoint.com/v2/url?u=http-3A__www.dealii.org_developer_doxygen_deal.II_DEALGlossary.html-23GlossGeneralizedSupport=DwIBaQ=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw=noUPzp6HQo5Ab1sMhXHEPDtKWiunYMqmACzbvcvljEk=xGxO7IMz8sGBENTwwyRKlCiJ7WNuI0hby0Co0ZQhaks= says FE_Q_Hierarchical has no generalized support points but the element actually returns 4 generalized support points in 2d with degree 1. Who is right? 3. Elements like FE_QLegendre return 0 generalized support points. Is there any information I can extract from the FE about the degrees of freedom or support points in this case? Thanks. -- Timo Heister http://www.math.clemson.edu/~heister/ -- 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
