Shows that it is possible to implement reverse mode autodiff using a variation on the dual numbers called the codual numbers
The codual numbers are a simple method of doing automatic differentiation in reverse mode. They contrast with the dual numbers which provide an easy way of doing automatic differentiation in forward mode. The difference between the two modes is that sometimes one is faster than the other.
The folklore appears to be that forward mode autodiff is easy to implement because it can be done using the beautiful algebra of dual numbers, while the same is assumed to not be the case for reverse mode. This repository presents a counterargument that a variant of the dual numbers – called the codual numbers – can be used to represent an implementation of reverse mode autodiff that is just as elegant and terse as can be done for forward mode. This