playground executable for experimenting with solvers and preconditioners

This MR adds an executable istl-playground that can be easily used to try out solvers or preconditioners. It reads a matrix and a rhs from MatrixMarket files or generates it if none is given and solves the systems with a solver from the matrix factory. This works also in parallel. The matrix can either be loaded on one rank and then be distributed on the ranks using ParMetis, or can be read from a distributed MatrixMarket file. As it is probably rarly used I added the EXCLUDE_FROM_ALL tag but added it as a test to avoid bit rotting.

I used it a lot in the last time. I hope that others could also benefit from it.

Thanks. I think such a program is useful and further serves as a nice example.

Only a bit of nit-picking... The auxilary programs in dune-grid are located in src and not bin. I'd advocate for consistency here.

It would be nice, if we could easily run tests with different accuracy, but it's not a necessary change to merge...

changed this line in version 3 of the diff

It would also be nice to have it for several SIMD types, but that blows up the compile time extremely.

Can we find a more informative name than istl-playground? At the very least: istl-solver-playground.

I changed it to istl-solver-playground. I'm open for better suggestions.

closed

@oliver.sander why did you close the MR. @nils.dreier should update according to the feedback, but I don't see a reason to close the MR.

reopened

added 2 commits

• 96c9d094 - move istl-playground to src
• 39825664 - rename istl-playground to istl-solver-playground

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added 1 commit

• ceb7ac0f - change folder name bin -> src in CMakeLists.txt

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Did I close it? That was not my intention---I must have hit a wrong button. My apologies.

mentioned in commit 9dae4be7

merged