[Libmesh-devel] boost::multi_array

[Roy S. <roy...@ic...>]

Here's another one to add to the planned post-0.5.0 API improvements:

We've got hundreds of "std::vector<std::vector<...> >" instances
floating around the code that could be replaced with boost's
"multi_array" container.  boost::multi_array keeps the data contiguous
(i.e. faster memory allocation and better locality), keeps it
rectangular (i.e. you can resize the array all at once, not row by
row), and supports slices and views (which should simplify my
projection code for one).

Unfortunately, it won't completely replace nested vectors.  Anything
that requires subvectors to be independently resizeable won't work,
for example.  Which is a shame, because what got me curious in the
first place was the problem of FE caching, which (even if we use
multiple FE objects for interiors/faces/edges and waste a few hundred
bytes on weird elements like pyramids) will still require at least a:

std::vector<boost::multiarray<Number, 3> > 
(e.g. cache[elemtype][facenum][basisnum][qp])
---
Roy