Dr. Bangerth, Thanks so much for your reply that pointed out my problem. Quadrature is applied to the residual expression, which includes both analytical and approximation. "right-hand-side" showed me that approximation can be obtained at quadrature point, before getting Jacobians and weighted. This is wonderful! I will keep up my work.
Happy Holidays! Best, Judy On Wednesday, December 22, 2021 at 12:27:59 AM UTC-5 Wolfgang Bangerth wrote: > On 12/21/21 8:59 AM, Judy Lee wrote: > > > > Can I make an expression u(x) for 1D analytical solution, that can take > > *q_index* for evaluating u(@ *q_index*), while skip obtaining *q_index* > > locations/points value? > > What is 'q_index'? It's usually the index (an integer) of a quadrature > point > on a cell. But u(x) is a function of a spatial variable (a point in the > domain). You can't ask for u(q_index). You have to say what that point is > where you want to evaluate the function. > > If I understand right then all you need is the ability to evaluate the > exact > solution at the location of a quadrature point. There are many examples of > how > this is done in the example programs (just search for where a right hand > side > is evaluated, for example). For evaluating the error u-uh, you can also > take a > look at step-7. > > Best > WB > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > www: http://www.math.colostate.edu/~bangerth/ > > -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/61474291-b0e9-4d5b-ba61-ff9f25944521n%40googlegroups.com.
