Fixed indexing error for modulus loss function

[fresleven]

Modulus Pull Request

Description

I forgot to include a commit when pushing the MHD example, which was also supposed to fixe the SWE PINO indexing incorrectly. This is the updated version

https://github.com/NVIDIA/modulus/pull/338#issuecomment-2094897687

Checklist

• [ ] I am familiar with the Contributing Guidelines.
• [ ] New or existing tests cover these changes.
• [ ] The documentation is up to date with these changes.
• [ ] The CHANGELOG.md is up to date with these changes.
• [ ] An issue is linked to this pull request.

Dependencies

[mnabian]

/blossom-ci

[NickGeneva]

/blossom-ci

[NickGeneva]

Instead cropping we should consider padding @ktangsali

We should pad the repo with a reflection boundary so we can compute edge derivatives. Makes the domain periodic iirc so the calculation is better.

See: https://github.com/NVIDIA/modulus-sym/blob/main/examples/darcy/darcy_PINO.py#L95

[NickGeneva]

Merged here: https://github.com/NVIDIA/modulus/pull/545

Thanks for the patch.