Thanks, Matt. 1) You mentioned that "PETSc calculates u_x, given the PetscFE and the coefficients (and the geometry).". Could you please direct me the source code that calculates u_x ?
2) Yes. Raviart-Thomas is one type of Nedelec element (Hdiv also called divergence conforming). Do you support Hcurl (curl conforming) Nedelec element ? On Tue, Apr 4, 2023 at 10:59 AM Matthew Knepley <knep...@gmail.com> wrote: > On Tue, Apr 4, 2023 at 10:45 AM neil liu <liufi...@gmail.com> wrote: > >> Hello, >> >> I am learning this case, >> https://petsc.org/release/src/snes/tutorials/ex62.c.html >> . And try to make myself familiar with the FEM (PetscFE) there. >> Then I have several questions. >> 1) PetscDSSetResidual >> <https://petsc.org/release/manualpages/DT/PetscDSSetResidual/>, >> For example, line 291, PetscCall >> <https://petsc.org/release/manualpages/Sys/PetscCall/>(PetscDSSetResidual >> <https://petsc.org/release/manualpages/DT/PetscDSSetResidual/>(ds, 0, >> f0_quadratic_u, f1_u)), here, f0_quadratic_u and f1_u is function >> pointers. Where have the input parameter for these functions been >> calculated, e.g., u_x. >> > > Line 291 sets callback functions. These functions are actually called in > the loop over the mesh which calculates the residual. > PETSc calculates u_x, given the PetscFE and the coefficients (and the > geometry). > > >> If I want to check the values of these parameters before line 291, how to >> print that ? >> > > I output many thing with -dm_plex_print_fem 5, but I am not sure if I > print out the field jet. It would be easy to add. > > >> 2) Does PetscFE support Nedelec element? Will it be painful to add these >> modules myself ? >> > > What kind? I think we support them, but have no tests. Take a look at our > support for Raviart-Thomas > > > https://gitlab.com/petsc/petsc/-/blob/main/src/dm/dt/dualspace/impls/lagrange/tutorials/ex1.c#L78 > > and see a use case here > > https://gitlab.com/petsc/petsc/-/blob/main/src/snes/tutorials/ex24.c > > Thanks, > > Matt > > >> Thanks , >> >> Xiaodong >> >> > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ > <http://www.cse.buffalo.edu/~knepley/> >
