geodesic_raytracing VS autodiff

Someone has written a geodesic ray tracer in C++.

If you're ever interested in building GR sims, I've got a lot of experience here and maintain a similar tool for GR raytracing here

This is untrue, I've shipped single executable binaries before with mingw. If you check out the latest project I've released, the only binary dependencies are libOpenCL.dll and the steam dll

I did build an implementation for a lot of this, so if you want this is probably a reasonable reference

I completely agree. Specifying the metric rather than the Christoffel symbols would make it much easier for the users. Something like https://github.com/autodiff/autodiff might just work as the metric tensor is made up of primitives.

Old username :D So far I have been using Eigen for linear algebra and NLOPT for optimization algorithms. I have found "autodiff" that hopefully looks easy to use: https://github.com/autodiff/autodiff

Forward-mode differentiation is easy to implement in C++ with templates, operator overloading, and dual numbers (https://en.wikipedia.org/wiki/Automatic_differentiation#Auto...). Some libraries such as autodiff (https://github.com/autodiff/autodiff) and CppAD (https://github.com/coin-or/CppAD) use this method.

I was thinking of adding [autodiff](https://github.com/autodiff/autodiff) in the future, mainly because it works seamlessly with *Eigen*. One big advantage would be that I could use it for AD for NonlinearSystems as well.