Numerical precision issue in rotate_vector
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Assessment
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Newbie friendliness
- 48/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Stale
- Tech stack
- matplotlib, python
- Domain
- data-visualization
Research direction
Start at lib/mpl_toolkits/basemap/init.py around the rotate_vector implementation referenced in the issue. Reproduce the wind-barb artifact with 32-bit float inputs, compare it with 64-bit inputs and the larger increment mentioned, and verify that the crystalline pattern is eliminated without changing expected rotation behavior.
Written by the indexing model from the issue text.
Description
Hi,
I ran into a numerical precision issue when using the rotate_vector function with 32bit floats as input data. In this case, the lat/lon increments used to determine the relative rotation between map projection and the lat/lon grid is chosen too small. The result was a cristalline structure in the plotted wind barbs which patches of barbs pointing in the exact same direction.
Converting the input to 64bit floats solves the issue for me, as did an increase of the increment to 1.0e-4.
Best regards,
Clemens
- Dominant language
- Python
- Stars
- 817
- Forks
- 395
- PR merge metrics
- No merged PRs in 30d
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