Hi everyone, I'm expanding step-12 in order to practice with DG. As written in the possible extensions, I should observe order p+1 in L^2 norm if I refine uniformly the mesh. So I decided to use the *ParsedConvergenceTable *to check the right EOC.
I have built a manufactured **smooth** solution and refined uniformly with finite element degree equal to *3*. I see indeed order 4=(3+1) in L^2 norm. However, it seems that the H^1 norm is converging initially with one order p (i.e. 3), but then the EOC seems to drop, as you can observe here (I'm using UMFPACK direct sparse solver) My guess is that we have some floating point issues, but I'm not sure. Any help in understanding what's going on is highly appreciated. cells dofs u_L2_norm u_H1_norm 64 1024 9.679e-08 - 1.223e-05 - 256 4096 6.045e-09 *4.00* 1.532e-06 *3.00 * 1024 16384 3.777e-10 *4.00* 1.918e-07 *3.00 * 4096 65536 2.360e-11 *4.00* 2.556e-08 *2.91* 16384 262144 1.475e-12 *4.00* 9.353e-09 *1.45* 65536 1048576 9.528e-14 *3.95* 8.801e-09* 0.09 * -- 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/69ca10ef-3949-40f1-a9bf-1d5d5eba341dn%40googlegroups.com.
