On Wednesday, 9 October 2013 at 08:30:11 UTC, Denis Shelomovskij
wrote:
09.10.2013 7:55, Nick B пишет:
On Tuesday, 8 October 2013 at 17:26:46 UTC, Stefan Frijters
wrote:
andrei wrote:
I too are interesteed in this area as well. Dennis do you only
plan to
focus on multidimensional arrays only, or will you incorporate
the above
matrices as well ??
What features are you proposing ?
I propose stuff for "multidimensional arrays only" as you
noted. And I plan just to revise my existing API [1] without
cardinal changes.
I.e. all I propose is rectangular multidimensional arrays
slicing and iterating. For matrix and math specific tasks see
DScience [2] and SciD [3]. The latter started as a fork of
DScience but became a separate project and is in development.
See its wiki [4]. Also such math oriented libraries have to be
partially (and the are) wrapper around LAPACK.
Also it will be interest to see features you (Stefan and Nick)
need e.g. as examples of code you want to compile with comments
if needed. Write down at least basic features for now.
[1]
http://denis-sh.bitbucket.org/unstandard/unstd.multidimensionalarray.html
[2] https://github.com/dscience-developers/dscience
[3] https://github.com/kyllingstad/scid
[4] https://github.com/kyllingstad/scid/wiki
Ok, off the top of my head, here are some of the points that
would be great for me to have. I apologize in advance if any of
them are trivial / irrelevant or out of scope; I have not had
time to get my hands dirty on this subject. Even if they are not
to be part of the generic multidimensional array (MDA) module,
these are things that I would then like to build my own
implementation of without having to work with instead of against
the things that will be in Phobos.
- Many of my operations involve looping over the array in no
particular order, so the first foreach example in your link #1
will be very useful.
- Another very common operation is accessing a lattice site and
looking at its neighbours to determine the outcome of the
operation. Of course this is easy for nested for-loops as I can
just nest one deeper and pre-calculate the neighbour offsets in
another array, but I don't know if there's a canonical way to do
this in terms of a foreach loop, and if this would add
requirements to the MDA. As an example, Python's numpy seems to
have 'generic_filter' for tasks like this[1]. In my testing it
was very slow though.
- I will have multiple MDAs, containing information like local
densities and velocities. These will affect each other in
calculations and thus being able to use zip and friends would be
very useful. This would require the MDA to be a range I guess?
- My code will use wrapped MPI[2] and HDF5[3] calls for
parallelism and parallel IO, respectively, and because of that I
will need some control over the memory layout. Nothing fancy, but
the usual C-style pointer arithmetic would need to work I think,
unless there's a nicer mechanism.
I hope these comments can be of some help.
Cheers,
Stefan
[1]
http://docs.scipy.org/doc/scipy/reference/generated/scipy.ndimage.filters.generic_filter.html#scipy.ndimage.filters.generic_filter
[2] http://en.wikipedia.org/wiki/Message_Passing_Interface
[3] http://www.hdfgroup.org/HDF5/
