[npr11]

Automatic differentiation. It's useful to so much computational work, but most people only get a cursory introduction to the topic (a rough intro to the minimum they need to know), whereas really understanding it seems to open up a lot of research.

[OkayPhysicist]

Oh man, I read a super cool article about that about a year ago. It provided an algorithm for automatic differentiation using an imaginary number such that it times itself equaled 0, but wasn't equal to zero itself. I'll try to find the link.

I don't know if this was it, but an explanation nonetheless https://medium.com/@omaraflak/automatic-differentiation-4d26...