Add support for (dune-functions) prefix resizing
Summary
When using ISTL blocked vectors for entity blocking, I came across the issue that the ordering was not able to provide individual sizes for each entity.
- Tag dispatched resize methods using the virtual interface of the ordering. This was not suitable for local ordering resizing.
- The ordering tree structure does not map directly to the container blocking, which makes it difficult to make resize based on its tree structure.
- dune-functions method of resizing is much more flexible and more intuitive than tag dispatched resizing.
Proposal
Use the dune-functions approach. That is, provide the ordering with a function size(MultiIndex) to which we pass a partial path (i.e. prefix) to the container and it should return the size for such path. In the dune-functions jargon, the ordering would be the size provider. Once this is possible, we are able to reuse dune-functions algorithms for ISTL backends...
// assume the following blocking
auto b = BlockVector<BlockVector<FieldVector<double,1>>>{};
auto prefix = MultiIndex<std::size_t,1>{}; // -> {}
auto base_size = gfs.ordering().size(predix); // get size of first level blocking
b.resize(base_size);
prefix.push_back(0); // -> {0}
for (std::size_t i = 0; i < base_size; ++i) {
prefix.back() = i; // -> {i}
auto block_size_i = gfs.ordering().size(prefix); // get size for block i
b[i].resize(block_size_i);
}...or, this could be done recursively with the dune-functions implementation:
auto b = BlockVector<BlockVector<FieldVector<double,1>>>{};
auto backend = Functions::istlVectorBackend(b);
backend.resize(gfs.ordering()); // calls size on ordering recursivelyDisclaimer
- I only tested dynamic entity booking for a two nested block vector
BlockVector<BlockVector<FieldVector<double,1>>>so far. -
The dune-functions grid function spaces are yet not adapted, but I assume that this is trivially feasibly since no complex trees used yet.DONE
Merge request reports
Activity
added 1 commit
- ed402e0e - Add size prefix to experimental dune functions
added 1 commit
- 2768af09 - Add prefix size implementation for direct leafs
added 1 commit
- e7290a6d - Add size implantation for lexicographic orderings
added 1 commit
- a3dbb13e - Assume direct leaf local orderings are always field vectors
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Apart from what I mentioned above, this is feature complete and is documented. @christi would you mind taking a look into this?
mentioned in merge request !557 (merged)
added 1 commit
- 6d58c643 - Reverse size prefix when mixing dune-functions and pdelab code
added 1 commit
- 81ee58c6 - Fix size provider for non blocked local orderings
added 2 commits
requested review from @christi
