JuliaDiff / JuliaDiff/DiffRules.jl

rule for tanh has catastrophic cancellation for |x| > 20

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#102 2 comments 0 reactions 0 assignees View on GitHub

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Dominant language
Julia
Stars
74
Forks
36
Avg merge
1d 1h
Merged PRs (30d)
1

Description

One could simply revert #30 to fix this, but if one wants CSE then it can be calculated from first principles. I started a discussion which has numerical examples.

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Research direction

Inspect the tanh derivative rule and review the changes in #30 first, then read the linked discussion for the numerical examples and proposed CSE approach. Done means the rule avoids catastrophic cancellation for |x| > 20 while matching the accurate derivative behavior shown in those examples.

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Assessment

Tech stack
julia
Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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