Fix Base.show StructuredMesh

[MarcoArtiano]

When the StructuredMesh was called without any mapping, the information was displayed incorrectly. See below.

Before

After

Same for 1D and 2D.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 78.94737% with 4 lines in your changes missing coverage. Please review.

Project coverage is 96.41%. Comparing base (6149104) to head (366b537).

Files with missing lines	Patch %	Lines
src/meshes/structured_mesh.jl	78.95%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2228      +/-   ##
==========================================
- Coverage   96.42%   96.41%   -0.01%     
==========================================
  Files         487      487              
  Lines       39345    39356      +11     
==========================================
+ Hits        37935    37942       +7     
- Misses       1410     1414       +4     

Flag	Coverage Δ
unittests	96.41% <78.95%> (-0.01%)	⬇️

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[MarcoArtiano]

Now, when no mapping is provided to StructuredMesh, Trixi displays the following information:

Analogously for 1D and 2D cases.

Fixed also when StructuredMesh is called with faces

[ranocha]

Thanks! What does the result look like when a mapping is passed?

[MarcoArtiano]

Thanks! What does the result look like when a mapping is passed?

The user defined function is

function mapping(xi_, eta_)
    # Transform input variables between -1 and 1 onto [0,3]
    xi = 1.5 * xi_ + 1.5
    eta = 1.5 * eta_ + 1.5

    y = eta + 3 / 8 * (cos(1.5 * pi * (2 * xi - 3) / 3) *
                       cos(0.5 * pi * (2 * eta - 3) / 3))

    x = xi + 3 / 8 * (cos(0.5 * pi * (2 * xi - 3) / 3) *
                      cos(2 * pi * (2 * y - 3) / 3))

    return SVector(x, y)
end

from structured_2d_dgsem/elixir_advection_free_stream.jl

This is how it is displayed at the moment. I'm not really a fan of this visualization and if you have any suggestion I may try different options. Before everything was displayed in one single line and because of that incorrectly reported on the terminal.

[ranocha]

Thanks, I'm fine with these changes. It would be nice to get feedback from @sloede as well.

[sloede]

Is there a way for custom mappings to just display the mapping function? Alternatively, I'd prefer to just write something like "custom mapping", since mapping functions might get long and this becomes ugly. But if you're keen on showing it here, I wouldn't be opposed either.

[MarcoArtiano]

Is there a way for custom mappings to just display the mapping function? Alternatively, I'd prefer to just write something like "custom mapping", since mapping functions might get long and this becomes ugly. But if you're keen on showing it here, I wouldn't be opposed either.

With the last commit at the moment when a custom mapping or faces are passed to StructuredMesh, the Base.show displays simply that.

Unfortunately I couldn't find an easier way to at least distinguish mapping and faces inside the Base.show functoin. I would like to avoid making changes in the StructuredMesh call where the variable mapping_as_string is generated, because it may affect the restart function in Trixi.jl. In any case, I could display something like "custom mapping/faces", or reverse the commit and revert to the previous version, where the entire function was displayed.

[ranocha]

@sloede Your decision. I am not against the previous (more verbose) version since the current output is already quite a bit...