In case you or anyone else knows, are there other libraries that implement a high performance sparse QR? Really, I need a Q-less QR factorization for sparse matrices. As far as I know, there are only two: one comes from MKL:

https://www.intel.com/content/www/us/en/developer/articles/t...

The other comes from SPQR, which is part of SuiteSparse:

https://people.engr.tamu.edu/davis/suitesparse.html

Part of the issue is that SPQR is dual licensed GPL/Commercial and the last time I checked a license was not cheap. Conversely, MKL has no redistribution fee, so it's been essentially the only option for this factorization if the code can't be bundled in a way compatible with the GPL.

Replying to [dead] sibling post from kxyvr: yes, Accelerate provides a Q-less sparse QR on Apple platforms (https://developer.apple.com/documentation/accelerate/sparse_..., in particular SparseFactorizationCholeskyAtA). I believe that MA49 from HSL does it as well, and may have more acceptable licensing than SuiteSparse depending on your situation.