Unfortunately it’s for my work so not currently public. One chunk of it which I would love to open source sometime, is basically just TRANSPORT but modern Python. Despite being a million years old, just second order matrix-style beam optics is actually still a really useful place to start for a lot of stuff. And with it all differentiable, one can do way more kinds of interesting optimisations.
What’s interesting is that the old Fortran source code for TRANSPORT is still out there if one digs, and most of it is taken up by thousands of lines of code that (1) implement a bunch of matrix multiplication that is now just one call to “jnp.einsum()“, and (2) implementing a tedious by-hand differentiation of those same calculations, in a few parameters, which is now basically inferior to just one call to “jax.grad()”. It’s amazing how modern tools can make hard stuff truly trivial.