[Numeric] HMatrix priorities

[Henning Thielemann]

Hi Huw,


On Wed, 8 Jul 2020, Huw Campbell wrote:

> I have a few questions:
>
> - Why are CSR and CSC 1 indexed? The early literature uses 0 indexing
> AFAICS, and it means that Ben Gamari's libsvd wrapper has to do extra
> leg work reindexing before calling its C code.

I may point you to my package 'lapack' and the underlying 'comfort-array' 
which addresses indexing in a very general manner:
    https://hackage.haskell.org/package/lapack

> - Should we try to move more of the library towards the general matrix
> `GMatrix`? At the moment there are not very many functions which
> actually use it (and it has partial record labels), and one can't
> project out back to any of the underlying matrix forms.

My lapack package has individual types for different matrix forms and thus 
better documents what is going on in your numeric code.

> - CI looks like it's only testing one version of GHC, do we have a
> policy on how many versions we support?

My lapack wrapper supports back to GHC-7.4.

> - What are all of your priorities? Dominic has mentioned a few use cases 
> around sparse matrices people have been working on.

I have heard many people asking for sparse matrices.

What do people think is the best low-level library to interface to? 
suitesparse?