Monthly Archives: January 2009

Server utilization: Joel on queuing

Joel Spolsky of Joel on Software fame mentions queuing theory in the latest StackOverflow podcast. He mentions a rule of thumb that wait times go up quickly as server utilization exceeds 80%. The same principle applies whether you’re talking about

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Posted in Math

Whatever happened to system administration?

You hardly hear anyone speak of “system administration” anymore. Now everything is “IT” (information technology). System administrators are now “IT professionals.” Why the change? Has it become politically incorrect to call the people who administer computer systems “system administrators”? I’ve

Posted in Uncategorized

Free Ubuntu Linux book

Andy Hunt announced this evening that Keir Thomas’ 170-page book Ubuntu Pocket Guide and Reference is available as a free PDF. It is also available on paper from Amazon.

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Posted in Computing

Exascale computing

In this podcast, Peter Kogge explains what it would take to increase our computing capacity by a factor of 1000. We can’t just do more of what we’re doing now and scale linearly. For example, one limitation is power consumption.

Posted in Computing

Six degrees of Paul Erdős

The goal of the game Six Degrees of Kevin Bacon is to connect actors to Kevin Bacon in as few steps as possible. For example, Elvis Presley can be linked to Kevin Bacon in two steps: Elvis Presley made a

Posted in Math

Cost-benefit analysis versus benefit-only analysis

Hardly anyone cares about statistics directly. People more often care about decisions they need to make with the help of statistics. This suggests that the statistics and decision-making process should be explicitly integrated. The name for this integrated approach is

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Posted in Statistics

Talent alone won’t pay the bills

Here’s a Washington Post article about an experiment. The newspaper asked world-famous violinist Joshua Bell to dress down and perform as a street musician at a DC metro stop. Hardly anyone paid attention. He earned $32.17 in tips. People routinely

Posted in Business

Two myths I learned in college: bathtub drains and airplane wings

Here are two things I was taught in college that were absolutely wrong. The Coriolis effect explains why bathtubs drain clockwise in the northern hemisphere. The Bernoulli effect explains how planes fly. These are not things that scientists believed at

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Posted in Science

Apple Mac turns 25 today

The Mac came out 25 years ago today. Here’s the article. Hat tip @divbyzero. I sold Macs for a little while. I worked at the UT computer store one summer. At the time, that store was the biggest distributor of

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Splitting a convex set through its center

Three days ago I raised the question How unevenly can you split a convex set through its center? Scott had asked in the comments what kind of sets split most unevenly through their centers. I didn’t have an answer at

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Posted in Math

Twitter is not micro-blogging

Twitter is often described as a micro-blogging platform. Twitter posts and like blog posts, except they’re limited to 140 characters (so they fit in a cell phone text message). You subscribe to Twitter posts (called “tweets”) sorta like you subscribe

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Probability distributions and object oriented programming

This post looks at applying object oriented programming ideas to probability distribution software. It explains the Liskov Substitution Principle and shows how it can keep you from falling into a subtle trap.

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Posted in Math, Software development

How to dry a wet book

This short audio program explains how to take care of a book that gets wet. The first step is to freeze it as soon as possible. One minute how-to #326

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Free optimization software from Microsoft

This morning I stumbled across Microsoft Solver Foundation, optimization software developed in C#. The site only mentions a free “express edition.” Sounds like they’re releasing a free version first and may sell an upgrade in the future. Here are the

Posted in Computing, Math

Distribution of time customers spend in coffee shops

How would you model the time customers spend in a coffee shop? This post is pure speculation based on no hard data whatsoever, which makes things considerably easier! If anyone has data or suggestions, please leave a comment. Here goes

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Posted in Math