On Fri, Apr 29, 2011 at 08:01:55AM -0000, Nguyen Van Dang wrote: > New question #154697 on DOLFIN: > https://answers.launchpad.net/dolfin/+question/154697 > > Hello, > > I am working with FEnics on C++. I want to take the values of basis function > at each vertex directly. I read BasisFunction.h online but I don't know how > to use this one. > > Finally, I found in "Poisson.h" (created from "Poisson.ufl" in > dolfin/demo/pde/poisson/cpp) class "poisson_finite_element_0" in which there > is function "evaluate_basis(unsigned int i, double* values, double* > coordinates, const ufc::cell& c)". > In "main.cpp" (in the same directory), I wrote: > unsigned int i; > double* values; > double* coordinates; > ufc::cell c; > poisson_finite_element_0 finite_element; > finite_element.evaluate_basis(i,values,coordinates,c); > I compiled it without any errors. > The problem is that how to input the value for c? > In fact, I have read the paper "efficient representation of computational > meshes" of A. Logg and I could make a loop for all cells as well as vertices. > However, the cell in this loop doesn't match with c anymore (because they > have different type). Moreover, it is difficult to initialize the cell data > structure: > c.entity_indices = new unsigned int [...]; > c.coordinates = new double[..]; > ..... > > Is there any simple way to do this? Do you have any examples working on basis > functions?
Look at the FiniteElement class and the function interpolate_vertex_values. More generally (for evaluation at arbitrary points), you can use the functions evaluate_basis or evaluate_basis_all. -- Anders _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
