Simeon David Schaub

Thanks for the quick response! What I am still wondering, is whether `similar_from_indices` could be used to preserve information about each axis, which in my case is covariance. For example,...

I think I mostly got it now, the only thing I'm still a bit confused about is the difference between the arguments `p1` and `p2`.

Ah, thanks, that makes sense! In CoolTensors, co- and contravariant indices can have an arbitrary order, so I don't think I will make use of this functionality, but that's good...

Can you just use it the other way, i.e. FiniteDifferences over Zygote instead of Zygote over FiniteDifferences? You could actually define a custom adjoint for `FiniteDifferenceMethod` which does this automatically...

Thinking about making `ComplexGradient` two real parameters instead of one complex one, so we could make use of `Zero` in some places. Would complicate some arithmetic, though.

I've written down some thoughts about this in FluxML/Zygote.jl#328 also. I still need to finish that though and will then try to adapt some of that in the docs here.

Most of the time, users shouldn't interact with Wirtinger objects at all. One of the main use case I see for them is as intermediary representations in mixed-mode AD implementations....

What has been superseded is `ComplexGradient`, now that we just use `Adjoint` for that. It seems like people still expressed interest in Wirtinger derivatives, so this might be something to...

I'll look into that, once I figured out the other issues.

Hmm, need to figure out why Diffractor is still broken