[deal.II] How can I add curl conforming boundary constraints to the Multigrid transfer matrices?

[Julian Roth]

Dear all,

I was trying to solve the Eddy Current Problem with Multigrid. 
I have curl-conforming boundary constraints, i.e. n x u = 0.

I managed to apply these to the system matrix via 
VectorTools::project_boundary_values_curl_conforming_l2()
Unlike step-16 where the same approach has been demonstrated for the 
LaplaceProblem, I didn't find any method,
which allows me to apply the before mentioned boundary constraints to the 
MGConstrainedDoFs object.
Thus I computed the curl conforming constraints in assemble_multigrid, when 
I instantiated the boundary_constraints on each level.
The matrix on the finest grid is the same as the system matrix, which means 
that my workaround should have worked.

How can I apply my boundary constraints to the transfer matrices between 
the level meshes, if they are not contained in MGConstrainedDoFs?

Currently I am still using:
MGTransferPrebuilt mg_transfer(mg_constrained_dofs);
mg_transfer.build_matrices(dof_handler);

Obviously this isn't correct though, since the boundary constraints haven't 
been accounted for.
How can I add curl conforming boundary constraints to the transfer matrices?

Is there any other way that I can deal with the curl conforming boundary 
conditions, when I am working with Multigrid?

Kind regards,

Julian


P.S. Note that my Multigrid approach is not MatrixFree. Thus I don't think 
that I can use
MGConstrainedDoFs.add_user_constraints()
since this only applies to MatrixFree methods.

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Re: [deal.II] Example not Compiling in deallii on Docker

[luca.heltai]

You are trying to compile the examples in the /usr/local directory. 

The default user in the dealii docker image is the “dealii” user, and it does 
not have write access to those directories. If you really want work inside the 
docker image, you should copy the directory of the example(s) you want to 
compile under /home/dealii and compile from there. 

However, the usual way people use the docker image is to mount a local 
directory into the image, e.g., calling 

docker run -v $HOME:$HOME -t -i dealii/dealii:latest bash

and then building your examples/programs/etc. in a local directory under your 
home folder path. In this way you use the image, without modifying its content, 
and the build results are left in your home directory (in the host computer, 
and not in the image, where the changes you make are discarded when you exit).

Best,
Luca.

> On 15 May 2020, at 11:44, Jack Urombo  wrote:
> 
> 
> 
> I have installed dealii on docker and when itry t run the examples i get the 
> error below. What am i doing wrong?
> 
> 
> 
> /usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/dealii-9.1.1-kbq6c5p67nir5zwpx5lbevwutndfivxz/share/deal.II/examples/step-6/CMakeFiles/CMakeTmp/testCCompiler.c
> 
>   try_compile() works only for enabled languages.  Currently these are:
> 
> C CXX
> 
>   See project() command to enable other languages.
> Call Stack (most recent call first):
>   CMakeLists.txt:38 (PROJECT)
> 
> 
> -- Check for working C compiler: /usr/bin/cc -- broken
> CMake Error at 
> /usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/cmake-3.14.4-7gmvmpryqyfj5m42vt5qj5tb27tw7un6/share/cmake-3.14/Modules/CMakeTestCCompiler.cmake:56
>  (file):
>   file failed to open for writing (No such file or directory):
> 
> 
> /usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/dealii-9.1.1-kbq6c5p67nir5zwpx5lbevwutndfivxz/share/deal.II/examples/step-6/CMakeFiles/CMakeError.log
> Call Stack (most recent call first):
>   CMakeLists.txt:38 (PROJECT)
> 
> 
> CMake Error at 
> /usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/cmake-3.14.4-7gmvmpryqyfj5m42vt5qj5tb27tw7un6/share/cmake-3.14/Modules/CMakeTestCCompiler.cmake:60
>  (message):
>   The C compiler
> 
> "/usr/bin/cc"
> 
>   is not able to compile a simple test program.
> 
>   It fails with the following output:
> 
> 
> 
>   
> 
>   CMake will not be able to correctly generate this project.
> Call Stack (most recent call first):
>   CMakeLists.txt:38 (PROJECT)
> 
> 
> -- Configuring incomplete, errors occurred!
> CMake Error: Cannot open file for write: 
> /usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/dealii-9.1.1-kbq6c5p67nir5zwpx5lbevwutndfivxz/share/deal.II/examples/step-6/CMakeCache.txt.tmp
> CMake Error: : System Error: Permission denied
> CMake Error: Unable to open cache file for save. 
> /usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/dealii-9.1.1-kbq6c5p67nir5zwpx5lbevwutndfivxz/share/deal.II/examples/step-6/CMakeCache.txt
> CMake Error: : System Error: Permission denied
> dealii@85f866bfa019:/usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/dealii-9.1.1-kbq6c5p67nir5zwpx5lbevwutndfivxz/share/deal.II/examples/step-6$
>  ^C
> dealii@85f866bfa019:/usr/local/opt/spack/linux-ubuntu16.04-x86_64/gcc-5.4.0/dealii-9.1.1-kbq6c5p67nir5zwpx5lbevwutndfivxz/share/deal.II/examples/step-6$
>  
> 
> 
> -- 
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