BDF ODE integrator slow
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- Dominant language
- C++
- Stars
- 839
- Forks
- 220
- Avg merge
- 2d 4h
- Merged PRs (30d)
- 14
Description
Description
With the switch to the new variadic ODE interface we also changed how error tolerances are being checked during the Newton iterations. Essentially the error tolerances are now also being checked for the sensitivities as the same time as for the ODE states. This lead to a significant slow-down of the BDF integrator ranging from 10-30% as reported on discourse. The reason for the change were
- with this scheme the Adams-Moulton integrator became actually stable as this one was unstable before
- this aligned the CVODES integrators with the RK45 scheme of handling things
Example
Expected Output
Same output is expected, but faster.
Current Version:
v3.3.0
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 at the BDF ODE integrator's Newton-iteration error-tolerance checks, then compare its handling of ODE states and sensitivities with the Adams-Moulton and RK45 integrators. Profile the reported slowdown while confirming that solver output remains unchanged; done means the BDF integrator preserves output and improves the 10–30% regression.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100