pymc-devs / pymc-devs/pytensor
Implement ScalarLoop grad
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- Dominant language
- Python
- Stars
- 644
- Forks
- 208
- Avg merge
- 2d 14h
- Merged PRs (30d)
- 16
Description
@aseyboldt mentioned we should be able to implement the gradient as another ScalarLoop, via forward auto-diff, which in this case should be equivalent to backward-autodiff.
It should also be possible to fuse the loops, but hopefully that's one thing the compilers can easily figure out, once they get merged inside the same Composite?
Originally posted by @ricardoV94 in https://github.com/pymc-devs/pytensor/issues/283#issuecomment-1539706699
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating the ScalarLoop implementation and its forward- and backward-autodiff paths, then inspect how loops are combined inside Composite. The work is complete when the gradient can be represented as another ScalarLoop and the existing autodiff behavior remains equivalent.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100