pymc-devs / pymc-devs/pytensor
Scan mixing of positive and negative mitmot taps is error-prone
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- Dominant language
- Python
- Stars
- 644
- Forks
- 208
- Avg merge
- 2d 14h
- Merged PRs (30d)
- 16
Description
Description
We had a subtle bug in the numba implementation of Scans that had a mix of positive/negative output taps. It should always be possible to create an equivalent Scan using only positive/negative taps. We should pick one representation and stick with it.
I suspect the JAX implementation may also have this bug
Found in #811
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 tracing the Scan implementation for mixed positive and negative output taps in the numba path, then compare the corresponding JAX implementation. The issue names no files or tests; done means equivalent Scans use one tap representation consistently and the mixed-tap bug is verified as fixed.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- machine-learning
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100