thank for the reply!! my fe degree is declared as "fe (FE_Q<dim>(degree+1), dim,FE_Q<dim>(degree), 1)" and I used "QGauss<dim> quadrature_formula(degree+2);" to calculate integral over the cell.
2016년 9월 20일 화요일 오전 9시 26분 6초 UTC-5, Praveen C 님의 말: > > > On Tue, Sep 20, 2016 at 7:49 PM, JAEKWANG KIM <jaekw...@gmail.com > <javascript:>> wrote: > >> Can I ask more about "the limits of our implementation of our quadrature >> formulas?". >> I wonder when it usually happens. >> >> >> Once I calculated drag coefficient, with Q1, my error is 10% compare to >> exact solution. >> However, I can 1.7% error when I use Q2 which is significant decrease! >> At Q3, I get 0.4% and At Q4 it starts to increase again 0.5%. >> If I go higher, then my error is more than 100%..... I really want to >> figure out why this happens.... >> >> To summarize >> From Q1~Q3... it shows significant decrease in error >> but it is not anymore at Q4 and Q5 >> > > Hi > > If you are using FE_Q space with uniformly spaced support points, then > there could be problem at higher degrees. Just to check, you should use > Gauss nodes, e.g. > > FE_Q(QGaussLobatto<1>(degree+1)) > > Best > praveen > -- 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.
