On Thu, 29 Oct 2009, Tim Kroeger wrote: > On Thu, 29 Oct 2009, Roy Stogner wrote: > >> On Thu, 29 Oct 2009, Tim Kroeger wrote: >>> >>> Is there any easy way to loop over all elems that are neighbors of a >>> given elem accross either a face or an edge? As fas as I understand, >>> Elem::neighbor() only cares about neighbors accross faces. On the >>> other hand, Elem::find_point_neighbors() does too much. I think, it >>> should be easy to implement a method Elem::find_edge_neighbors() >>> analogously to Elem::find_point_neighbors(), where just each call to >>> Elem::contains_vertex_of() is replaced with a call to >>> Elem::contains_edge_of(), the latter is implemented analogously to >>> Elem::contains_vertex_of() with the only difference that for returning >>> true, it requires at least *two* vertices of the one element contained >>> to be contained in the other. What do you guys think? If you agree >>> that this would be correct, I'd be happy to do this (easy and >>> straightforward) task. >> >> Sounds good... >> >> Something that needs thought, though: there's a limitation in >> find_point_neighbors() which will become a more significant limitation >> in find_edge_neighbors(): behavior on adaptive meshes. >> >> With find_point_neighbors, an elem can share a point with its neighbor >> without sharing any nodes with its neighbor, for some first-order elements >> two levels apart or some second-order elements three levels apart. >> This is only a minor problem for our patch recovery estimator, which >> doesn't quite grow patches in the most optimal way, so I never worried >> about it. > > Hmm... There seems to be some misunderstanding either on my side or on yours. > To check whether two elems (say, A and B) have a common point, > Elem::find_point_neighbors calls A.contains_point(nB) for all nodes nB of B > and B.contains_point(nA) for all nodes nA of A. The method > Elem::contains_point(), however, does *not* check whether the given point is > a node of the respective element; rather it uses an inverse map to check > whether the point is contained in the element. Hence, if I understand > correctly what you mean, these cases are caught correctly (and would be by > Elem::find_edge_neighbors() the same way). Or did you mean something > different?
Ah, you're right! It's been a while since I wrote find_point_neighbors; I thought it was just testing node sharing. The inverse_map based point test ought to work fine, both for it and for your proposed find_edge_neighbors. --- Roy ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
