Re: [eigen] A 15-dimensional sparse matrix or tensor?

[Pavel Holoborodko <pavel@xxxxxxxxxxxxxxx>]

What operations do you need to do with such tensors?

You can implement the simplest way to store the sparse tensor - by storing the coordinates of the non-zero values + values itself.

Then implement tensor operations for such a storage format.

If density of non-zeros is very low (as you say), then this simple data structure will be efficient and simple.

On Wed, Sep 27, 2023 at 9:21 PM Janek Kozicki (yade) <jkozicki-yade@xxxxxxxxx> wrote:

Hi,

in my incoming work on implementing Loop Quantum Gravity I will need
a 15-dimensional sparse matrix (or tensor) to store the quantum
gravity data in a 15-dimensional basis. The data is very sparse, most
of it are zeros. But if I tried to use a regular vector<vector<....>> 15 times
I will quickly run out of memory.


So, does libeigen offer such data type?

best regards
Janek Kozicki

--
Janek Kozicki, PhD. DSc. Arch. Assoc. Prof.
Gdansk University of Technology (Gdansk Tech)
Faculty of Applied Physics and Mathematics
Institute of Physics and Applied Computer Science
Division of Theoretical Physics and Quantum Information
--
http://yade-dem.org/
http://pg.edu.pl/p/jan-kozicki-19725
http://mostwiedzy.pl/en/jan-kozicki,19725-1