Elixir: ImplicitEuler solve with sparse jacobian

[sbairos]

No description provided.

[github-actions]

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[DanielDoehring]

Nice work, we should probably put the hacks at the beginning of the elixir into an extension file, see for instance

https://github.com/trixi-framework/Trixi.jl/blob/main/ext/TrixiNLsolveExt.jl

This way, we also avoid making sparsediff and symbolics direct dependencies of trixi

[sbairos]

Is this approximately what you had in mind for the extension? I tried moving the using SparseDiffTools, Symbolics over to the extension too but then the elixir wouldn't run. Seems like we need this import in the elixir as well?

[DanielDoehring]

Is this approximately what you had in mind for the extension? I tried moving the using SparseDiffTools, Symbolics over to the extension too but then the elixir wouldn't run. Seems like we need this import in the elixir as well?

Yes, we still need to import them in the elixir. The package extension framework is a trick to avoid direct dependence of "main Trixi" on these very specific packages.

[DanielDoehring]

Ah and one more thing: Remember to periodically update your mirror of the main branch and merge that main branch into this feature to stay up to date with what is happening upstream to avoid ugly merge conflicts when this is ready to go

[DanielDoehring]

I am not 100% sure if the extension is the right way, since we overload only Base functions and nothing from Trixi itself. Maybe we move the module into the elixirs again and import/use it there.