Small doubles are serialized incorrectly by fwrite

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
38/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
r
Domain
data

Research direction

Start at the fwrite entry point and reproduce the issue with a data.table containing A=1e-323. Trace how this very small double is converted for output, then verify that the serialized value preserves the input within the expected floating-point precision.

Written by the indexing model from the issue text.

Description

fwrite
> # This is correct, up to some unavoidable loss in precision
> data.table(A=1e-323)
               A
1: 9.881313e-324
> # But this is not
> fwrite(data.table(A=1e-323))
A
1.1125369292536e-308
Dominant language
R
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Forks
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Avg merge
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Merged PRs (30d)
4

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