Unexpected arithmetic when multiplying field
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bug
- Dominant language
- Python
- Stars
- 150
- Forks
- 23
- Avg merge
- 1d 11h
- Merged PRs (30d)
- 2
Description
Hi folks - first attempt to report features this way!
Have encountered an unexpected behaviour when combining fields - should this happen?
Is it something to do with units? T is degC here, maybe we are expecting K?
(see attached file)
amv.nc.gz
>>> import cf
>>> cf.__version__
'3.5.1'
>>> data=cf.read('amv.nc')[0]
>>> data.array[0]
array([[20.51099598]])
>>> (data-data).array[0]
array([[0.]])
>>> (data-1*data).array[0]
array([[273.15]])
>>> (1*data-1*data).array[0]
array([[0.]])
>>>
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First steps
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Research direction
Start by reproducing the arithmetic shown in the issue with the attached amv.nc.gz file and compare the units on data before and after each expression. Trace the field and unit handling used by subtraction and multiplication; confirm the intended Celsius behavior with the project maintainers. Done means the inconsistent results are explained and corrected, with coverage for the demonstrated expressions.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- data
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100