[deal.II] Matrix-free with Petsc vectors

Hello, I have a working matrix-based solver using Petsc vectors which i am currently trying to transform to a matrix-free code. When I use the deal.ii Matrix-free infrastructure with Petsc-vectors eg. using the distribute_local_to_global function I get the following error message: error: cann

[deal.II] GMRES as a Geometric Multigrid Smoother

Hi all, I have a matrix-free code which uses geometric multigrid as a preconditioner (based on step 37). I've found that for my case the Chebyshev smoother does not work well under certain conditions. From literature I think replacing this with few iterations of GMRES as a smoother may work we

[deal.II] Matrix-Free and FE_Nothing

Hi all, I am trying to implement a MatrixFree code which uses FE_Q and FE_Nothing elements. Evaluating the matrix-free operator works correctly without the FE_Nothing elements but when I add them the code the operator tries to access indices which are out of range in the read_dof_values functio

[deal.II] Re: Matrix-Free and FE_Nothing

ge of cells using create_cell_subrange_hp_by_index() > <https://dealii.org/current/doxygen/deal.II/classMatrixFree.html#a6528454a674f0958be4c06aac27f9b26> > > and then loop over the cells in the subrange. > > Best, > > Bruno > > On Thursday, February 20, 2025 at 8

[deal.II] Non-analytical Matrix-Free coefficient

Hello everyone, I am currently developing a matrix-free code which has a non-analytical spatially varying coefficient. As in step-37 I am using a Table<2, VectorizedArray > to store evaluations of the coefficient at all the quad