Re: [deal.II] Convergence failure in step 0.

To extend over what Wolfgang said, the most likely causes for failure with the Chebyshev preconditioner are: - the vector supplying the matrix diagonal (via the field AdditionalData::preconditioner) contains Inf or NaN entries, which in turn result from either a ill-formed differential operato

Re: [deal.II] Convergence failure in step 0.

Thank you Wolfgang. I didin't dive much into the Chebyshev preconditioner because I'm not familiar with it. I assume it's because the CG solver inside Chebyshev preconditioner didn't converge or what. But as you stated, if NaN should only get from NaN elements and divided by zero, then I may fi

Re: [deal.II] Convergence failure in step 0.

It's strange that the iteration breaks at step 0. If I try right preconditioning, it breaks at step 1 with nan. Besides, if there is only on multigrid level, the problem is solved correctly with 1 iteration, so matrices should be correct. The coarse solution is good enough for smoothing. Th

Re: [deal.II] How to read mesh for the geometry, which has two materials.

Thank you Prof. for the information. I'll check it out. On Fri, Feb 10, 2023 at 11:25 PM Wolfgang Bangerth wrote: > > Deepika, > GridGenerator has a number of functions that do similar things to what you > want to do, such as plate_with_a_hole(), channel_with_hole(), specifically > merging dif

Re: [deal.II] Using DoFTools::map_dofs_to_support_points for two-field with FE_DGPMonomial

On 2/11/23 04:09, Masoud Ahmadi wrote: My goal of using this function is simply to get the DoF of some specific nodes which I know their coordinates; so, are there any alternative options that I won't have to use this function? In order to determine the DoF indices for a given vertex, you ca

[deal.II] deal.II Newsletter #241

Hello everyone! This is deal.II newsletter #241. It automatically reports recently merged features and discussions about the deal.II finite element library. ## Below you find a list of recently proposed or merged features: #14793: doc: replace FE_DGRT with correct name (proposed by tjhei) htt

[deal.II] Convergence failure in step 0.

Hi, I'm solving a multi-component problem in MatrixFree framework, preconditioned by geometric multigrid. The code runs good for several cases except one (with different geometry and boundary condition). The error is "Iterative method reported convergence failure in step 0. The residua

[deal.II] Re: Creating a plot in dealii

Hello, DataOut is made to add data to a mesh. It cannot be used to do what you want. The easiest way to do what you want is to write the vectors to a file using print() and then do the plot using matlab or python. Best, Bruno On Saturday, February 11, 2023 at 9:27:06 AM UTC-5 ce21...@smail.ii

[deal.II] Discontinous Galerkin with periodic boundary conditions

Dear deal.ii community, first of all, a big thank you for all the effort going into this software. I am currently developing an application and I stumbled upon implementing periodic boundary conditions for discontinuous Lagrange elements. I found the following thread https://groups.google.com/g/