Communications of the ACM
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How the “Frontier” Became the Slogan of Uncontrolled AI
Artificial intelligence (AI) has been billed as the next frontier of humanity: the newly available expanse whose exploration …
From Daniel Lemire's Blog
19 random digits is not enough to uniquely identify all human beings
Suppose that you assigned everyone an 19 digit number. What is the probability that two human beings would have the same number? It is an instance of the Birthday...
From Daniel Lemire's Blog
Consider using constexpr static function variables for performance in C++
When programming, we often need constant variables that are used within a single function. For example, you may want to look up characters from a table. The following...
From Daniel Lemire's Blog
Science and Technology links (March 11 2023)
Robert Metcalfe won the Turing Award (the ‘Computer Science Nobel Prize’) for his work on early networking. According to DBLP, Metcalfe published 11 journal articles...
From Daniel Lemire's Blog
Programming-language popularity by GitHub pull requests
GitHub is probably the most popular software repository in the world. One important feature on GitHub is the ‘pull request’: we often contribute to a piece of software...
From Daniel Lemire's Blog
Are your memory-bound benchmarking timings normally distributed?
When optimizing software, we routinely measure the time that takes a given function or task. The typical assumption is that we get a normal distribution, and so...
From Daniel Lemire's Blog
What are we going to do about ChatGPT?
Generative artificial intelligence, and in particular ChatGPT, has taken the world by storm. Some intellectuals are proposing we create a worldwide ban on advanced...
From Daniel Lemire's Blog
C++20: consteval and constexpr functions
Optimizing compilers seek try to push as much of the computation as possible at compile time. In modern C++, you can declare a function as ‘constexpr’, meaningContinue...
From Daniel Lemire's Blog
Can GPT pass my programming courses?
Professeur Caplan reports that ChatGPT, the new AI that is all the rage, can pass his economics midterm and get an A. What about computer science ? I submittedContinue...
From Daniel Lemire's Blog
Counting cycles and instructions on ARM-based Apple systems
In my blog post Counting cycles and instructions on the Apple M1 processor, I showed how we could have access to “performance counters” to count how many cycles...
From Daniel Lemire's Blog
Runtime asserts are not free
When writing software in C and C++, it is common to add C asserts to check that some conditions are satisfied at runtime. Often, it is a simple comparison between...
From Daniel Lemire's Blog
Science and Technology links (March 11 2023)
In 1500, China was the largest economy in the world, followed by India and France. The USA did not exist yet. In 1700, 4% of human beings lived in France. In the...
From Daniel Lemire's Blog
Trimming spaces from strings faster with SVE on an Amazon Graviton 3 processor
Programmers sometimes need to trim, or remove, characters, such as spaces from strings. It might be a surprising expensive task. In C, the following function is...
From Daniel Lemire's Blog
Float-parsing benchmark: Regular Visual Studio, ClangCL and Linux GCC
Windows users have choices when it comes to C++ programming. You may choose to stick with the regular Visual Studio. If you prefer, Microsoft makes available ClangCL...
From Daniel Lemire's Blog
Regular Visual Studio versus ClangCL
If you are programming in C++ using Microsoft tools, you can use the traditional Visual Studio compiler. Or you can use LLVM as a front-end (ClangCL). Let us compare...
From Daniel Lemire's Blog
Computing the UTF-8 size of a Latin 1 string quickly (AVX edition)
Computers represent strings using bytes. Most often, we use the Unicode standard to represent characters in bytes. The universal format to exchange strings online...
From Daniel Lemire's Blog
Science and Technology links (February 12 2023)
Kenny finds that the returns due to education are declining. Rich countries are spending more on education, with comparatively weaker test results. It costs more...
From Daniel Lemire's Blog
Bit Hacking (with Go code)
At a fundamental level, a programmer needs to manipulate bits. Modern processors operate over data by loading in ‘registers’ and not individual bits. Thus a programmer...
From Daniel Lemire's Blog
Serializing IPs quickly in C++
On the Internet, we often use 32-bit addresses which we serialize as strings such as 192.128.0.1. The string corresponds to the Integer address 0xc0800001 (3229614081...
From Daniel Lemire's Blog
Move or copy your strings? Possible performance impacts
You sometimes want to add a string to an existing data structure. For example, the C++17 template ‘std::optional’ may be used to represent a possible string value...
From Daniel Lemire's Blog