[MikeBattaglia]

There are a few good resources. Here is a good blog post with some introduction:

https://towardsdatascience.com/forward-mode-automatic-differ...

Some thorough notes from MIT: https://book.sciml.ai/notes/08-Forward-Mode_Automatic_Differ...

Here is a teacher who taught a class using these, calling the dual element dx instead of h:

https://cornellmath.wordpress.com/2007/08/28/non-nonstandard...