Hello Jaekwang, I am trying to generate some log-log plots, and wondering if you used the functions in deal.ii to generate the figure. If not, what did you use?
Thanks, Jiaqi 在 2016年9月29日星期四 UTC-4上午11:41:48，Jaekwang Kim写道： > > > <https://lh3.googleusercontent.com/-dkfwJvgPEmc/V-00Y-c4tzI/AAAAAAAAA5s/pb0Z-IBRe-An_S39dSDzxWg1k5GJlEbKQCLcB/s1600/step7plotting.jpg> > > Hi all, I have question on error behavior of FEM. > > I thought that the order of error is O(h^p) where h is a mesh-size and p > is polynomial degree we use in approximation. > > So, I thought that if I plot an error with number of mesh in log-log > scale, than the graph will show -p slope. > However, I the error behaves little bit different from my expectation. > > For example, I use a step7 tutorial program (which solves Helmholtz > decomposition and compares the FEM solution with exact solution.) > > The error curve showed more steep slope whenever I increase polynomial > degree approximation however, the slope is not (-p). > I reached slope (-3) when I used fifth-degree polynomial approximation... > > You can check this behavior in attached picture. > > Until now, I have considered, > > 1. Mapping(From reference cell to real cell) degree (which is originally > set to 1 but I used higher mapping) > 2. Instead of Qgauss quadrature, I am using QgaussLobatto Quadrature for > any integration over cells. > 3. Shape function , again I tried to use QgaussLobatto node point for > this....) > > is there any suggestion that I need to fix more? > or my first prediction that the slope will show '-p' or error will just > behave O(h^p) was wrong? > > I am always thank you for all guys! > > Jaekwang Kim > -- 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.
