Thank you very much for your answer. So for the first function VectorTools::point_value(dof_handler,solution,point,values);
I can specify the observed point in real coordiante, solution vector and dof_handler to get the values right? For the second one, assuming that I am using QGauss for solving the system, can I use QGaussLobatto to get the quadrature points on the edge of a cell and get the values from this? With the second function, I see that it returns 9 components: 3 for each parameters: temp_solution_re[0], temp_solution_re[1], temp_solution_re[3] when I call fe_values[vector_re].get_function_values(solution, temp_solution_re); I really want to know which one is the solution for my vector in x,y,z direction? Best regards, Pham Ngoc Kien Vào Th 5, 14 thg 3, 2019 vào lúc 14:08 Wolfgang Bangerth < bange...@colostate.edu> đã viết: > On 3/13/19 8:21 PM, Phạm Ngọc Kiên wrote: > > I am testing my codes for output the solution at a point in my numerical > model. > > I saw in the library 2 ways to do this task. The first one is to use > > VectorTools::point_value() function and the second one is > > fe_values.get_function_values(). > > These functions are really used in very different contexts. The first of > these > is when you want to evaluate a solution vector at some arbitrary point in > the > domain. As a consequence, you have to specify this point when you call the > function. > > The second function is used when you want to evaluate the function at very > specific points, namely the quadrature points of the current cell. You can > of > course only use this if the point at which you want to evaluate the > solution > happens to be a quadrature point of the current cell, and not just any > point > anywhere. In return the second function is then vastly more efficient than > the > first. > > Does this help? > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bange...@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. > For more options, visit https://groups.google.com/d/optout. > -- 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.
