# Monthly Archives: February 2006

## 0.203188

In a “Computing Science” column titled “Rumours and Errours,” not quite a year ago, a leading role went to the nondescript number 0.203188. That number emerged from a simulation of how rumors spread through a society; given certain assumptions, 0.203188 … Continue reading

## Taxation without rationalization

I am the child of a bookkeeper, and I’ve inherited the habit of double-checking receipts and balancing accounts. My friends make fun of me when I carefully note down the dime that I put in a parking meter, but lately … Continue reading

## Life after algebra

Three weeks ago, Duke Helfand of the Los Angeles Times wrote a thoughtful article on high school algebra. A one-semester course in algebra has recently become a requirement for graduation in the Los Angeles unified school district, and many students … Continue reading

## Playfair’s Powerpoint Presentation

“To those interested in the effective visual communication of quantitative phenomena, William Playfair’s Atlas is like the Bible: an ancient and revered book that is often cited but rarely read.” —Howard Wainer and Ian Spence The Commercial and Political Atlas … Continue reading

## Zeroing in on zeta zeros

Casual observers of the mathematical arts might be forgiven for feeling that mathematicians sometimes make rapid progress in the wrong direction. For example, the concept of a prime number is simple enough to be understood by anyone who knows a … Continue reading

## Bidirectional subroutines

More on reversible computing. If all it took to reverse a computation was stepping through a program backwards, there wouldn’t be much to say about the idea. In general, this kind of straightforward reversal doesn’t work. However, I have learned … Continue reading

## Packed primes

A few weeks ago I reported on two talks about patterns in prime numbers—pairs of primes that lie close together and long sequences of primes in arithmetic progression. Thomas J Engelsma writes to tell me of a closely related undertaking: … Continue reading

## A reversible eraser

Still more on reversible and zero-energy computing (see earlier bit-player posts here and here, and the American Scientist column): M. Maissam Barkeshli of the University of California at Berkeley has a preprint titled “Dissipationless Information Erasure and Landauer’s Principle.” (The … Continue reading

## Newton and Notwen

This is another loose end from my new column on reversible computing (now available online; also see the earlier bit-player item on swapping). In the column I mention Henry G. Baker’s idea of reversing Newton’s method for approximating the square … Continue reading

## Rediscovering America

In today’s New York Times (registration required), Gina Kolata writes on rediscoveries and reinventions in the sciences. Her essay is based in part on the experience of Rakesh V. Vohra of Northwestern University, who has discovered that one of his … Continue reading