ARPACK situation

An open letter to all ARPACK users and developers

I’m writing this email to discuss the future of ARPACK. The problem is this: it’s a widely-used library, but it seems abandoned upstream (and upstream, to whom this is addressed, can confirm or deny). This has resulted in the problem of many mini-forks as each organisation distributes ARPACK patches its own way, and very often, for the same bugs. These are the ones I could find:

Additionally, the Mathworks (they make Matlab) probably also has their own version of ARPACK, but I wasn’t able to find a public version of it, nor an email to send them questions to. If someone could contact them, it would be nice to let them know.

These all seem to have modified ARPACK in some way, with minor or major bugfixes, and as far as I can tell, have mostly done so independently. To me, this seems like unnecessary work, if we’re all patching the library again and again and making our own private forks. What I therefore propose is to have some sort of central location for it and we all pool our efforts on this one location. I think it would be easiest to use Andreas Klöckner’s existing fork on github, since this requires the least maintenance and work from anyone. All that it requires for now is for each of the people above to see what patches they have made and transplant them to the git repo.

It would be helpful if upstream could confirm that they are happy with ARPACK development continuing on github and mention this on the ARPACK webpage, so that new people who are interested on ARPACK can be redirected.

– Jordi G. H.
GNU Octave developer