Daniel-lemire - daniel-lemire.com - Daniel Lemire's blog
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Picking N distinct numbers at random: how to do it fast? 16 Aug 2013 | 08:14 pm
To test my algorithms, I like to generate synthetic data. To do so, I often need to generate distinct randomly chosen numbers from a range of values. For example, maybe I want to pick 2 distinct integ...
Privacy and the Internet: Is Facebook evil? 9 Aug 2013 | 10:40 pm
For several of my classes, I open Facebook groups so that my students can exchange online. In some instances, it has worked great. Facebook tends to do a better job than school-provided posting boards...
Honey bees are not going extinct 26 Jul 2013 | 08:24 pm
There is much argument about what science is. To some people, it appears to be mostly the belief that information should be derived reputed sources. That is, if your belief regarding the age of the Ea...
Big-O notation and real-world performance 11 Jul 2013 | 06:35 pm
Classical Newtonian mechanics is always mathematically consistent. However, Newtonian mechanics assumes that bodies move without friction and that we stay far from the speed of light. When your car is...
Should computer scientists run experiments? 10 Jul 2013 | 08:16 pm
Jeffrey Ullman, a famous computer science professor, published an essay pushing back about the need to run experiments in computer science. Apparently, some conference reviewers gave him a hard time r...
Fast integer compression in Java 8 Jul 2013 | 11:04 pm
Last year, we published a fast C++ library to quickly compress and decompress arrays of integers. Out of habit, I ported it to Java and published it under the name JavaFastPFOR library. Unlike generi...
Staying sharp requires “intellectual gardening” 25 Jun 2013 | 07:47 pm
Gardening requires consistency. A beautiful garden is unstable. Some plants want to expand their reach and kill out the competition. Some plants are simply out of their element and need a little bit o...
Hashing and the Birthday paradox: a cautionary tale 18 Jun 2013 | 12:31 am
If you meet a stranger, the probability that he will have the same birth date as yourself is probably less than 1%. It is roughly 1/365 if you make simplifying assumptions. The Birthday paradox is the...
Meetings are like sex 13 Jun 2013 | 02:46 am
Meetings are like sex. Everybody thinks that they are good at it… until they ask for the truth. We never have real discussions about it: I did not want to say anything… but you know this meeting thing...
Why I never give straight answers 4 Jun 2013 | 08:20 am
There are some questions that you should never answer. This is true when you are facing justice, your angry wife, or students. Carl Zimmer, a famous science writer, complains about how students keep a...
