JuliaArrays / JuliaArrays/StaticArrays.jl
Changes from #908 lead to `NaN`s in AD jacobians for methods using `norm2` on `StaticArray` types
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Description
I recently opened this issue on ForwardDiff.jl: https://github.com/JuliaDiff/ForwardDiff.jl/issues/547. @KristofferC identified #908 as the PR that introduced the breaking changes; see his comment here: https://github.com/JuliaArrays/StaticArrays.jl/pull/908#issuecomment-932820498. @mateuszbaran said this is because of a missing check in StaticArrays.jl for norm2, which LinearAlgebra already does; see his comment here: https://github.com/JuliaArrays/StaticArrays.jl/pull/908#issuecomment-932825220.
I am not familiar with the internals of StaticArrays.jl, so any help with this is be much appreciated. Thank you!
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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 reading the linked ForwardDiff.jl issue and StaticArrays.jl PR #908, then trace the norm2 entry point and the referenced discussion about the missing check. Reproduce the NaN AD jacobians for methods using norm2 on StaticArray types; done means those jacobians no longer contain NaNs and the behavior is covered by a regression test.
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Assessment
- Tech stack
- julia
- Domain
- backend
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100