torchinterp1d and KeOps are incompatible with vmap

[adam-coogan]

vmap is not compatible with torchinterp1d or keops. Both use torch.autograd.Function, which is not compatible with vmap by default. This will be a problem if you want to e.g. vmap over a bunch of NFWs for simulating or computing magnifications, since they may use torchinterp1d via FlatLambdaCDM. This is fixable, but requires modifying torchinterp1d and keops. I've opened issues in both projects' repos.

This isn't really our responsibility to fix, but I wanted to document this since it's good to be aware of this restriction.

[ConnorStoneAstro]

We no longer depend on torchinterp1d and only have limited compatibility with keops. It would be good to open another issue specifically for keops compatibility.