Skip to content

Fix definitions of == and isless #103

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Fix definitions of == and isless #103

wants to merge 1 commit into from

Conversation

@devmotion
Copy link
Member

@devmotion devmotion commented Mar 13, 2024

Given the definitions of == and isequal in ForwardDiff#master, the PR reverts 337539f (see #10) and defines both ==(x, y) and isequal(x, y) in terms of both value(x) and epsilon(x) etc. This makes

  • the definitions in ForwardDiff and DualNumbers consistent,
  • the definitions of == and isequal in DualNumbers consistent,
  • the definitions of == and isequal mathematically correct.

Additionally, the PR fixes isless: According to its docstring, isless(x, y) should

Test whether `x` is less than `y`, according to a fixed total order (defined together with `isequal`). `isless` is not defined for pairs `(x, y)` of all types. However, if it is defined, it is expected to satisfy the following:
- If `isless(x, y)` is defined, then so is `isless(y, x)` and `isequal(x, y)`, and exactly one of those three yields true.
- The relation defined by `isless` is transitive, i.e., `isless(x, y)` && `isless(y, z)` implies `isless(x, z)`.

On the master branch, however, the first requirement is not satisfied (e.g., choose x = dual(3, 0.5) and y = dual(3, 1.0): then neither isless(x, y), isless(y, x), nor isequal(x, y) is satisfied).

cc @andreasnoack who was involved in #10

@codecov
Copy link

codecov bot commented Mar 13, 2024 •
edited
Loading

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 51.88%. Comparing base (d9251a7) to head (d52f6a3).
⚠️ Report is 2 commits behind head on master.

Files with missing lines Patch % Lines
src/dual.jl 83.33% 1 Missing ⚠️
Additional details and impacted files 
@@            Coverage Diff             @@
##           master     #103      +/-   ##
==========================================
+ Coverage   50.94%   51.88%   +0.94%     
==========================================
  Files           2        2              
  Lines         212      212              
==========================================
+ Hits          108      110       +2     
+ Misses        104      102       -2

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

@devmotion devmotion requested a review from mcabbott August 16, 2024 14:28
@devmotion
Copy link
Member Author

devmotion commented Nov 27, 2024

@mcabbott I think you might be interested in this change.

@mcabbott
Copy link
Member

mcabbott commented Nov 27, 2024

This looks right to me, at first glance.

I see that #104 recently adopted the other convention.

But I have never used this package and am unsure who does, or the value of maintaining it in parallel to ForwardDiff.

@dlfivefifty
Copy link
Collaborator

dlfivefifty commented Nov 27, 2024

This package predates ForwardDiff.jl and its value is mostly in its simplicity and accessibility.

The "right" thing to do is move ForwardDiff.Dual here. But that would require someone to take the initiative, and some functionality would need to be added to ForwardDiff.Dual to maintain feature parity.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@mcabbott mcabbott Awaiting requested review from mcabbott

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

4 participants

@devmotion @mcabbott @dlfivefifty