FAfanf2·Oct 30, 2020Submission
Errol: Binary floating-point to decimal string conversion algorithm
2 points · Open discussionmarcandrysco
Errol
C++2016–2020
marcandrysco / Errol
Errol
Binary floating-point to decimal string conversion algorithm.
4Distinct people
4Mentions
0Explicit recommenders
106GitHub stars
What to know before exploring
What it is
Binary floating-point to decimal string conversion algorithm.
GitHub
Where it is used
No documented product use has been verified yet.
What people are saying
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This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.
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Mentions over time
HN mentions by year4 dated mentions
Observed mentions: 2016-01-17 17:44:50 UTC to 2020-10-30 12:43:10 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2016 | 2016-01-01 00:00:00 UTC | 2017-01-01 00:00:00 UTC | 2 | 0 | 2 |
| 2017 | 2017-01-01 00:00:00 UTC | 2018-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2018 | 2018-01-01 00:00:00 UTC | 2019-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 1 | 1 | 0 |
What Hacker News says
4 sourceshttps://github.com/marcandrysco/Errol
> Our original evaluation of Errol against the prior work of Grisu3 was erroneous. The evaluation indicates a 2x speed improvement over Grisu3. However, corrected performance measurements show a 2x speed loss to Grisu3.
In 0.30000000000000004Author here. We intend for the GitHub repo (https://github.com/marcandrysco/Errol) to be the primary source for Errol. We still want to add a few improvements to the existing implementation: selecting the middle-most shortest number and an implementation for 32-bit floats (and maybe __float128).
In Printing Floating-Point Numbers: A Faster, Always Correct Method [pdf]http://goto.ucsd.edu/~andrysco/errol/ seems to be the artifact in question. (My friend also noted that there is a Github repo in https://github.com/marcandrysco/Errol, but I'm not sure if it is intended to be canonical.)
> Python currently uses David Gay's algorithm and would likely benefit from Errol3. [...] the algorithm becomes susceptible to FP rounding modes and susceptible to C compilers generating code with double rounding when mixing 64-bit doubles with 80-bit extended precision.
That would be really problematic since double-double arithmetic relies on the recovery of errors from prior operations. If you are interested in the integer-only algorithm, Rust's Grisu3 implementation derives from my own public-domain reimplementation of Grisu [1].
[1] https://github.com/lifthrasiir/rust-strconv
In Printing Floating-Point Numbers: A Faster, Always Correct Method [pdf]