dragonbox
ryu
dragonbox | ryu | |
---|---|---|
9 | 12 | |
498 | 1,152 | |
- | - | |
9.0 | 5.9 | |
5 days ago | 2 months ago | |
C++ | C++ | |
Apache License 2.0 | Apache License 2.0 |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
dragonbox
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23 years into my career, I still love PHP and JavaScript
Apparently exact minimal float-to-string conversion is more recent than I thought, and many languages used to print more (Python?) or less (PHP) decimal digits than necessary to uniquely identify the bit pattern. Python correctly prints 46000.80 + 553.04 as 46553.840000000004, but I don't know if it ever prints more digits than needed. One recent algorithm for printing floats exactly is https://github.com/ulfjack/ryu, though I'm unaware what's the state-of-the-art (https://github.com/jk-jeon/dragonbox claims to be a benchmark and the best algorithm).
- Dragonbox: Fast Float-to-String Conversion
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C++ I wrote a simple and fast formatting library for strings
A recent update to fmt was posted to r/cpp 3 days ago (https://www.reddit.com/r/cpp/comments/vrxkt0/fmt_90_released_with_improvements_to_floating/), and since that's still fresh on people's minds, they'll wonder how yours compares; and they'll probably wonder how it compares in terms of precision, round trip-ability, and performance of DragonBox https://github.com/jk-jeon/dragonbox. By "they", I probably mean "me" :D.
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I created something much faster than a std::string
Existing fast and correct float-to-string implementations are out there. Just use them: https://github.com/jk-jeon/dragonbox. Or maybe use your stdlib if it has good support
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How to read ascii files faster?
Parse floats faster with dragonbox
- Dragonbox 1.1.0 is released (a fast float-to-string conversion algorithm)
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C++20 std::format is already std::regex 2.0 situation.
Even if what you say is true, it makes little sense to not reuse it. There are other concerns here and one of them is code size. But to address the performance issue, fmtlib is doing under 50ns for most fp numbers via dragonbox(https://github.com/jk-jeon/dragonbox has the chart). So still cpu bound, but all FP output is CPU bound. At this point, what prices are we trading for faster?
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First release of dragonbox, a fast float-to-string conversion algorithm, is available
There are some benchmarks in https://github.com/jk-jeon/dragonbox#performance. TL;DR it's faster than other state of the art algorithms like Ryu, Schubfach and variations of Grisu. We saw a nice speed up when switching from Grisu3 to Dragonbox in {fmt}: https://github.com/fmtlib/fmt/pull/1882 and it has been improved even more since then.
ryu
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Printing double aka the most difficult problem in computer sciences
Nah. This is about ryu printf.
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Parquet: More than just “Turbo CSV”
> Google put in significant engineering effort into "Ryu", a parsing library for double-precision floating point numbers: https://github.com/ulfjack/ryu
It's not a parsing library, but a printing one, i.e., double -> string. https://github.com/fastfloat/fast_float is a parsing library, i.e., string -> double, not by Google though, but was indeed motivated by parsing JSON fast https://lemire.me/blog/2020/03/10/fast-float-parsing-in-prac...
- Faster way to convert double to string, not using "%f"?
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After obtaning a CS degree and 16 years of experience in industry, I feel somewhat confident that I can answer your programming questions correctly. Ask me anything
Me and Ryu agree that the answer should be 0.30000000000000004
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23 years into my career, I still love PHP and JavaScript
Apparently exact minimal float-to-string conversion is more recent than I thought, and many languages used to print more (Python?) or less (PHP) decimal digits than necessary to uniquely identify the bit pattern. Python correctly prints 46000.80 + 553.04 as 46553.840000000004, but I don't know if it ever prints more digits than needed. One recent algorithm for printing floats exactly is https://github.com/ulfjack/ryu, though I'm unaware what's the state-of-the-art (https://github.com/jk-jeon/dragonbox claims to be a benchmark and the best algorithm).
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What's the most elegant algo in your subjective view and why?
On the huge speedup side, you have the Ryū algorithm for decimal conversion (Video, Source), which is now finding its way in most standard libraries. But it isn't a hack, and a very dense, complex and precise algo, nothing like the fast-and-loose inverse square root.
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C++ devs at FAANG companies, what kind of work do you do?
Used a wizard's magic to print "3.14" faster
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how to make ftoa procedure from scratch
Here's a paper that details an optimized algorithm (reference implementation). It also contains a description of a correct, but slow algorithm as well as references to classic papers on the subject. Earlier the classic implementation was the dtoa one included in netlib by David Gay.
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Dragonbox 1.1.0 is released (a fast float-to-string conversion algorithm)
At the very core of all these theoretical stuffs, there is the theory of continued fractions. This is an immensely useful monster which I even dare call as the ultimate tool for floating-point formatting/parsing that everyone who wants to contribute in this field should learn. Before I learned continued fractions, my main tool for proving stuffs was the minmax Euclid algorithm (which is one of the greatest contributions of the wonderful Ryu paper), but it turns out that it is actually just a quite straightforward application of the theory of continued fractions. The main role minmax Euclid algorithm played was to estimate the maximum size of possible errors, but with continued fractions it is even possible to find the list of all examples that generate errors above a given threshold. This is something I desperately wanted but really couldn't do back in 2020.
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FastDoubleParser: Java port of Daniel Lemires fast_double_parser
Ryū algorithm, the converse (doubles to strings), is also much faster than using Java's number formatting classes.
https://github.com/ulfjack/ryu/blob/master/src/main/java/inf...
What are some alternatives?
fast_float - Fast and exact implementation of the C++ from_chars functions for number types: 4x to 10x faster than strtod, part of GCC 12 and WebKit/Safari
C++ Format - A modern formatting library
concise-encoding - The secure data format for a modern world
ryu - Ryu component-based software defined networking framework
proust - Compiling implementation of mustache
dtoa-benchmark - C++ double-to-string conversion benchmark
rapidgzip - Gzip Decompression and Random Access for Modern Multi-Core Machines
itoa - Fast integer to ascii / integer to string conversion
cpp-xstring - A system to handle strings easier and faster
oss-fuzz - OSS-Fuzz - continuous fuzzing for open source software.