JuliaArrays / JuliaArrays/StaticArrays.jl
Cholesky Update
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- Dominant language
- Julia
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- 844
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- Avg merge
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- Merged PRs (30d)
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Description
There's a couple of functions in LinearAlgebra.jl around updating Cholesky decompositions:
lowrankupdate!lowrandowndate!
You can find them starting here:
https://github.com/JuliaLang/LinearAlgebra.jl/blob/27b0f1321777fd2f935b8b9f1cefc61e12114b29/src/cholesky.jl#L882
This looks like a lot of mutating code, but would it be possible to use Accessors.jl to emulate this mutating behaviour? The annoying thing about lowrankupdate! is that it destroys the input vector, so the non-mutating versions lowrankupdate have to copy everything (hence allocations). Being able to get this to work for StaticArrays allows me to bypass these allocations and wierd side-effects. How feasible do you think this is?
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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 in src/cholesky.jl around the linked definitions of lowrankupdate! and lowrandowndate!, then examine how their mutating behavior affects the non-mutating lowrankupdate variants. Investigate whether Accessors.jl can support the requested StaticArrays behavior without destroying the input vector or requiring copies; done means a concrete feasibility result and a defined path for reducing those allocations and side effects.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- julia
- Domain
- performance
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 38/100