I sent this to julia-users a long, long time ago: https://groups.google.com/g/julia-users/c/DJRxApmpJmU/m/NqepNaX5ARIJ
Clearly it needs updating for twelve years of Julia evolution, but it may be useful to you. Or interesting at least. It's the same as in LAPACK's SRC/VARIANTS/lu/REC/ , and that has a better illustration of how it works. QR was to be done, as was cleaning up the code, but I never got back to it. I never bothered with generalizing to starting with a block of size 2^k for k > 0. That should be manageable by starting at the correct 'pseudo column' not_j = j + block_size...
I sent this to julia-users a long, long time ago: https://groups.google.com/g/julia-users/c/DJRxApmpJmU/m/NqepNaX5ARIJ
Clearly it needs updating for twelve years of Julia evolution, but it may be useful to you. Or interesting at least. It's the same as in LAPACK's SRC/VARIANTS/lu/REC/ , and that has a better illustration of how it works. QR was to be done, as was cleaning up the code, but I never got back to it. I never bothered with generalizing to starting with a block of size 2^k for k > 0. That should be manageable by starting at the correct 'pseudo column' not_j = j + block_size...