From: Steffen Petersen <steffen.petersen@tu...>  20060402 11:55:40

Roy Stogner schrieb: > > On the QUAD elements, we handled flipped edges by taking the negative > of the odd shape functions on those edges, which works fine. > > On the HEX27, it looks like we're handling flipped edges by mapping > xi to xi, eta to eta, or zeta to zeta, depending on the edge. > Obviously this mapping gives you the negative of odd shape > functions... but it doesn't give you the negative of their > derivatives! Am I missing something, or is this incorrect? This seems to be a bug in the 3D hierarchic shapes (and I just got poor results from a convergence test for the HEX27 hierarchics). It seems that no one has really used the 3D hierarchics so far. For the 3D Berstein shapes I had adopted the finite differences scheme that was used in libMesh to compute the shape derivatives for triangular elements. For the moderate orders that had been implemented so far this appears to work fine, but I guess it has limitations when used with high polynimial orders. Steffen > We now (or whenever SourceForge gets their CVS server working again, > anyway) have hierarchics implemented for arbitrary n on EDGE2/3 and > QUAD8/9 elements, by the way. They only seem to work well up to n=11 > or so, though; I'm not sure whether it's the floating point function > evaluations or the matrix conditioning that blows up there, but > something goes haywire. >  > Roy > > >  > This SF.Net email is sponsored by xPML, a groundbreaking scripting language > that extends applications into web and mobile media. Attend the live > webcast > and join the prime developer group breaking into this new coding territory! > http://sel.asus.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 > _______________________________________________ > Libmeshdevel mailing list > Libmeshdevel@... > https://lists.sourceforge.net/lists/listinfo/libmeshdevel 