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Tracking issue for extra floating-point logarithm constants #50540

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clarfonthey opened this issue May 8, 2018 · 15 comments · Fixed by #69249
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Tracking issue for extra floating-point logarithm constants #50540

clarfonthey opened this issue May 8, 2018 · 15 comments · Fixed by #69249
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B-unstable Blocker: Implemented in the nightly compiler and unstable. C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.

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@clarfonthey
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Specifically, LOG10_2 and LOG2_10. PR: #50539
@leonardo-m leonardo-m mentioned this issue May 10, 2018
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@XAMPPRocky XAMPPRocky added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC labels Oct 2, 2018
@clarfonthey
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Has anyone used these constants at all and want to pitch in for stabilisation of these? These have landed for a while and I'm curious how many people are using them.

@kennytm
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kennytm commented Dec 1, 2018

+1 for stabilization. (Tried to see if log2(10) exists and found that it is unstable 🙄.)

@clarfonthey
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(Mind providing the specific use case? Curious to see if people are using this for anything other than scientific computing.)

@kennytm
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kennytm commented Dec 1, 2018

@clarcharr to estimate the "−log2(probability)" of collision of two values chosen randomly from a set, which will be used to derive the probability of collision of N values (≈ 1 − e-pN2/2, p ≪ 1, N ≫ 1).

log2 is chosen instead of natural log because the set size is often 2n (e.g. u32), but sometimes it is drawn from a set of n decimal digits which would then involve n·log2(10).

@iliekturtles
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One hartley is = log2(10) shannons (bits). Currently the constant is duplicated in uom.

@clarfonthey
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I can't @ anyone from the libs team but do you think we'd be able to start an FCP for this?

@varkor
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varkor commented Sep 28, 2019

cc @rust-lang/libs for a FCP.

@alexcrichton
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@rfcbot fcp merge

I believe the stabilization includes core::{f32, f64}::{LOG2_10, LOG10_2}.

@rfcbot
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rfcbot commented Sep 30, 2019 •
edited by SimonSapin
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Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

@rfcbot rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Sep 30, 2019
@rfcbot rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Nov 21, 2019
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rfcbot commented Nov 21, 2019

🔔 This is now entering its final comment period, as per the review above. 🔔

@m-ou-se m-ou-se mentioned this issue Nov 26, 2019
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@jonas-schievink jonas-schievink added the B-unstable Blocker: Implemented in the nightly compiler and unstable. label Nov 26, 2019
@rfcbot
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rfcbot commented Dec 1, 2019

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

The RFC will be merged soon.

@rfcbot rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Dec 1, 2019
@LeSeulArtichaut
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@alexcrichton Does this need a stabilization report/PR?

@clarfonthey
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It needs a PR. Not sure if we should include TAU in that though; @m-ou-se, would you be willing to open a separate tracking issue for that, considering how that wasn't included in the FCP for this one?

@m-ou-se
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m-ou-se commented Feb 16, 2020

@clarfon There is already #66770.

@clarfonthey
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Oh, my bad. I for some reason noticed that this issue got linked in the PR and thought that there wasn't a separate tracking issue.

@LeSeulArtichaut LeSeulArtichaut mentioned this issue Feb 17, 2020
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JohnTitor added a commit to JohnTitor/rust that referenced this issue Feb 18, 2020
@JohnTitor
Rollup merge of rust-lang#69249 - LeSeulArtichaut:stabilize-logs-cons…
6d2b367 
…ts, r=sfackler

Stabilize {f32, f64}::{LOG2_10, LOG10_2}

Following the decision to stabilize `LOG2_10` and `LOG10_2` in rust-lang#50540 (comment).

Closes rust-lang#50540.
r? @sfackler
@bors bors closed this as completed in 20c4835 Feb 18, 2020
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B-unstable Blocker: Implemented in the nightly compiler and unstable. C-tracking-issue Category: An issue tracking the progress of sth. like the implementation of an RFC disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.
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Stabilize {f32, f64}::{LOG2_10, LOG10_2} LeSeulArtichaut/rust
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@alexcrichton @kennytm @m-ou-se @jonas-schievink @varkor @XAMPPRocky @iliekturtles @clarfonthey @rfcbot @LeSeulArtichaut