Add vmap support for PyTorch operators

[zou3519]

We're looking for more motivated open-source developers to help build out functorch (and PyTorch, since functorch is now just a part of PyTorch). Below is a selection of good first issues.

• vmap support for nansum, nanmean pytorch#91174
• vmap support for torch.complex pytorch#91175
• vmap support for torch.copysign pytorch#91176
• vmap support for torch.index_fill pytorch#91177
• vmap support for special bessel functions pytorch#91402
• vmap support for torch.tril, torch.triu pytorch#91403
• vmap support for torch.trace pytorch#91404
• vmap support for linalg.lu_factor pytorch#91415
• Add vmap support for torch.linalg.vander pytorch#91700

In general there's a high barrier to developing PyTorch and/or functorch. We've collected topics and information over at the PyTorch Developer Wiki

[msaroufim]

Would you to happen to have more? Would love to grab something but all the existing issues seem taken

[zou3519]

@msaroufim I added some more to the list, thanks for your interest