[usernametaken29]

The thing about linear algebra that strikes me as funny is that I faintly remember every instructor I ever have met says it is easy. Just learn the matrix cookbook and you’ll be good. At last, when you actually implement it, the ideas are simple in theory but in practice you’ll run into quadratic runtime almost all the time and it’s really hard to do well on CPUs. So is linear algebra hard? Maybe not on paper but in reality it’s really fucking difficult to get it to do what you want precisely and quickly

[bsoles]

The theory of (basic) linear algebra is pretty easy. The practice of proper linear algebra is very difficult. People spend entire careers on things like error propagation in matrix operations. There are entire books on inverting matrices using a litany of approaches using things like QR décomposition, SVD, etc. I think it is fascinating...