JuliaDiff / JuliaDiff/ForwardDiff.jl
Prohibit setindex! call if element of Jacobian is zero
Nobody has claimed this yet.
- Dominant language
- Julia
- Stars
- 1k
- Forks
- 160
- PR merge metrics
- No merged PRs in 30d
Description
I want to provide a sparse matrix to jacobian!, see this thread on Discourse.
However, setting zero-valued elements in a sparse matrix is expensive, because one needs to search if that element exists and has a non-zero value that is to be overwritten.
I propose that before the Jacobian/Hessian is filled, it is set to zero or emptied. Then setindex! is only called it the element is non-zero.
Contributor guide
No contributing guide indexed for this repository
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 with the linked setindex! call in src/jacobian.jl and trace how jacobian! and Hessian outputs are initialized and filled. Check the Discourse thread for the sparse-matrix context, then verify that zero-valued elements no longer trigger setindex! while non-zero Jacobian or Hessian elements are still written correctly.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- julia
- Domain
- performance
- Issue type
- Feature
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100