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
Science and Technology links (October 17th 2020)
Computer vision (i.e., artificial intelligence) and cameras are used in London to monitor citizens with respect to social distancing. A fecal transplant from old...
From Daniel Lemire's Blog
Why is 0.1 + 0.2 not equal to 0.3?
In most programming languages, the value 0.1 + 0.2 differs from 0.3. Let us try it out in Node (JavaScript): > 0.1 + 0.2 == 0.3 false Yet 1 + 2 is equal to 3. Why...
From Daniel Lemire's Blog
Science and Technology links (October 3rd 2020)
The mortality rate for kids under five have fallen by 60% since 1990. Samsung new storage drives are both affordable and really fast (up to 7GB/s). Alzheimer’sContinue...
From Daniel Lemire's Blog
How expensive is integer-overflow trapping in C++?
Integers in programming languages have a valid range but arithmetic operations can result in values that exceed such ranges. For example, adding two large integers...
From Daniel Lemire's Blog
Science and Technology links (September 19th 2020)
A large city dating back 4,300 years has been discovered in China. It predates the Chinese civilization. At its center was a wide pyramid supporting a 20-acre palace...
From Daniel Lemire's Blog
Parsing floats in C++: benchmarking strtod vs. from_chars
Programmers often need to convert a string into a floating-point numbers. For example, you might get the string “3.1416” and you would like to get the resulting...
From Daniel Lemire's Blog
Good students find questions, not answers
It is often believed that learning is a simple matter of collecting answers and replies. I suspect that “learn mechanistically how to answer the questions” isContinue...
From Daniel Lemire's Blog
Science and Technology links (September 5th 2020)
Single cells are able to navigate complex mazes. E.g., it works with mouse pancreatic cancer cells. Body builders and athletes sometimes take a supplement called...
From Daniel Lemire's Blog
Sentinels can be faster
A standard trick in programming is to use “sentinel values”. These are special values that represent metadata efficiently. The C language represents strings asContinue...
From Daniel Lemire's Blog
Science and Technology links (August 29th 2020)
In children, higher video game time is positively associated with cognition (i.e., kids who play more video games are smarter). Note that it does not follow that...
From Daniel Lemire's Blog
Science and Technology links (August 9th 2020)
The BBC reports that diversity and anti-bias training is of little use and may even be counterproductive if the goal is reduce biases: “The effect of bias training...
From Daniel Lemire's Blog
Performance tip: constructing many non-trivial objects is slow
I started programming professionally when Java came out and right about when C++ was the “hot new thing”. Following the then-current fashion, I looked down at C...
From Daniel Lemire's Blog
Science and Technology links (August 1st 2020)
In Japan, a large dam is being constructed almost entirely by robots. Naked mole rats are mammals that do not age in the sense that their fitness and mortalityContinue...
From Daniel Lemire's Blog
Science and Technology links (July 25th 2020)
I was taught that human beings only arrived to America recently (15,000 years ago). It turns out that it is wrong. There were human beings in America 30,000 years...
From Daniel Lemire's Blog
Avoid character-by-character processing when performance matters
When processing strings, it is tempting to view them as arrays of characters (or bytes) and to process them as such. Suppose that you would like to determine whether...
From Daniel Lemire's Blog
Downloading files faster by tweaking headers
I was given a puzzle recently. Someone was parsing JSON files downloaded from the network from a bioinformatics URI. One JSON library was twice as fast at the other...
From Daniel Lemire's Blog
The cost of runtime dispatch
For high-performance software, it is sometimes needed to use different functions, depending on what the hardware supports. You might write different functions,Continue...
From Daniel Lemire's Blog
Science is the belief in the ignorance of experts
Science is the belief in the ignorance of experts said Richard Feynman. Feynman had a Nobel prize in physics. He was a remarquable educator: his lecture notes are...
From Daniel Lemire's Blog
Science and Technology links (July 11th 2020)
Some upcoming Mercedes cars will have augmented reality head-up displays. Intel’s new standard for high-speed cables (thunderbolt) supports 3 GB/s bandwidth. (This...
From Daniel Lemire's Blog