Monthly Archives: October 2008

Tarnlund claims to have proof P != NP

Sten-Ake Tarnlund claims to have proved that P != NP, the most famous conjecture in theoretical computer science. Here’s the paper on arXiv. Since proposed proofs of famous theorems usually turn out to be incorrect, it’s too early to get

Tagged with:
Posted in Uncategorized

One thing to remember in economics

Signal vs Noise had this quote from Warren Buffet. One thing to remember in economics is that you can’t do one thing in economics. There are always other effects that come out of it. As I’ve heard someone say, the

Tagged with: ,
Posted in Business

Better R console fonts

The default installation of R on Windows uses Courier New for the console font. Unfortunately, this font offers low contrast between the letter ‘l’ and the number ’1.’ There is also poor contrast between the letter ‘O’ and the number

Tagged with: ,
Posted in Typography

The cost of breaking things down and putting them back together

The basic approach to solving large, complex problems is to break them down into smaller problems then re-assemble the solutions. The total cost of a solution has to account for not only the cost of solving the all the sub-problems,

Tagged with:
Posted in Business, Computing

R, Excel, and the Windows clipboard

The Windows version of R has functions for reading from and writing to the clipboard. These can be used to move data back and forth between R and Windows applications such as Excel. However, there are a few gotchas. See

Tagged with: , ,
Posted in Computing

Hubble and astronomy papers

The Hubble Space Telescope “has become the source of roughly 25 percent of all published astronomy research papers” since the telescope was fitted with corrective lenses in 1993 according to Discover magazine, September 2008.

Posted in Science

Why there will always be programmers

The latest episode of the .NET Rocks podcast is an interview with Robert Martin. In the interview, Robert Martin gives his view of why there will always be programmers. Here’s my summary/paraphrase of his argument. Systems are full of details,

Tagged with:
Posted in Software development

Odd wine bottle

Unusual wine bottle on display at Café Amore, Cypress (Houston) Texas. Three liter hand-crafted crystal bottle of 1999 Super Toscani IGT wine, about three feet tall. Here’s a close-up of the label. Other wine posts: the politics, science, and math

Tagged with:
Posted in Uncategorized

42nd Carnival of Mathematics

It’s the 42nd Carnival of Mathematics. Don’t panic! First, the customary trivia about the number of the Carnival. 42, Jackie Robinson’s jersey number, is the only number retired by all Major League Baseball teams. 42 is a domino game, especially

Tagged with:
Posted in Math

Three math diagrams

Here are three pages containing diagrams that each summarize several theorems. The distribution relationships page summarizing around 40 relationships between around 20 statistical distributions. The modes of convergence page has three diagrams like the following that explain when one kind

Tagged with: , ,
Posted in Math, Statistics

Five kinds of subscripts in R

Five kinds of things can be subscripts in R, and they all behave differently. Positive integers Negative integers Zero Booleans Nothing For all examples below, let x be the vector (3, 1, 4, 1, 5, 9). Positive integers Ordinary vector

Tagged with:
Posted in Uncategorized

Freeing Vista diskspace

Scott Hanselman has a good article on freeing up disk space under Windows Vista. I tried one of his suggestions and immediately freed up seven GB on my wife’s PC.

Tagged with:
Posted in Computing

What happens when you add a new teller?

Suppose a small bank has only one teller. Customers take an average of 10 minutes to serve and they arrive at the rate of 5.8 per hour. What will the expected waiting time be? What happens if you add another

Tagged with:
Posted in Math

Data synthesis

This post makes a good point: what we call data analysis would be called data synthesis if stuck to the ordinary meanings of the words. Via Andrew Gelman.

Posted in Science, Statistics

Nearly everyone is above average

Most people have a higher than average number of legs. The vast majority of people have two legs. But some people have no legs or one leg.  So the average number of legs will be just slightly less than 2,

Posted in Statistics