Thanks for writing this series. I'm really interested in this stuff and I'm sorta writing my own version where I'm implementing the algorithms in lisp: http://geokon-gh.github.io/linearsystems/ (I'm sure it's quite amateurish compared to what you're doing)

Nothing quite forces you to understand the issues deeply like implementing it in code!

I haven't gotten to LS/QR yet (just getting the LU working correctly was quite tricky), but when I do I'll make sure to reference your series :)