Blog Feed: The Endeavour — The blog of John D. Cook

I have a conjecture regarding statistical methods: The probability of a method being used drops by at least a factor of 2 for every parameter that has to be determined by trial-and-error. A method could have a dozen inputs, and if they’re all intuitively meaningful, it might be adopted. But if there is even one parameter that [...]

Relearning to type

Published on 2012-06-17 17:18:25

I’m starting to feel some strain in my hands, so I’m going to take Vivek Haldar’s advice: Act like you do have RSI, and change your set up right now to avoid it. For one thing, I bought an ergonomic keyboard this weekend. It lets me hold my hands in a more relaxed position. When I learned to [...]

Institutional mediocrity

Published on 2012-06-15 07:08:59

Here are a couple quotes I’ve run across lately. Both say that attempts to filter out the low end of human thought inevitably filter out some of the high end too. First, from Doug Gwyn: Unix was not designed to stop its users from doing stupid things, as that would also stop them from doing clever things. Second, [...]

Institutional mediocrity

Published on 2012-06-15 07:08:59

Root-finding with noisy functions

Published on 2012-06-14 20:09:52

Suppose you have function g(x) and you want to find x so that g(x) = 0. However, you don’t have direct access to g(x). Instead you can evaluate f(x) which is g(x) plus random noise. Typically f(x) would be an approximation of g(x) based on Monte Carlo simulation. I have spent countless hours solving problems [...]

Root-finding with noisy functions

Published on 2012-06-14 20:09:52

Unhappy programmers are all alike

Published on 2012-06-14 07:07:30

A recent pair of articles from Dr. Dobbs reminded me of a famous line from Anna Karenina: All happy families are alike, but each unhappy family is unhappy in its own way. Paul Johnson argues that Tolstoy had it backward, that there is more variety in happy families. He argues that there are “obvious, recurring patterns in [...]

Unhappy programmers are all alike

Published on 2012-06-14 07:07:30

Technology hype curve

Published on 2012-06-13 11:25:25

via Wikipedia

Technology hype curve

Published on 2012-06-13 11:25:25

via Wikipedia

Making a singular matrix non-singular

Published on 2012-06-13 06:38:24

Someone asked me on Twitter Is there a trick to make an singular (non-invertible) matrix invertible? The only response I could think of in less than 140 characters was Depends on what you’re trying to accomplish. Here I’ll give a longer explanation. So, can you change a singular matrix just a little to make it non-singular? Yes, and in fact [...]

Making a singular matrix non-singular

Published on 2012-06-13 06:38:24

Obsession

Published on 2012-06-11 08:22:39

Obsession has come to have a positive connotation. Individuals and companies brag about being obsessed about this or that. But obsession is a psychosis, and the original meaning of the word is still valid. Obsession, according to the canons of psychology, occurs when an innocuous idea is substituted for a painful one. The victim simply avoids [...]

Obsession

Published on 2012-06-11 08:22:39

Running Linux on Azure

Published on 2012-06-09 11:07:27

Microsoft began offering Linux virtual machine hosting on its Azure platform this week. I created an Ubuntu 12.04 server this morning and everything worked smoothly. I found it much easier to create and connect to a virtual machine on Azure than on Amazon EC2.

Running Linux on Azure

Published on 2012-06-09 11:07:27

Painting with Numbers

Published on 2012-06-09 10:42:13

Painting with Numbers is a new book of advice on making numerical presentations. The book is very elementary. It contains no math beyond arithmetic, and it focuses almost entirely on financial data in Excel spreadsheets. But it does have useful tips. A lot of presentations would be easier to understand if the presenter had read this [...]

Painting with Numbers

Published on 2012-06-09 10:42:13

Visual Basic and coyotes

Published on 2012-06-08 10:16:57

David S. Platt calls VB 6 developers a silent majority. He says the vast majority of VB developers did not want the power (and associated complexity) of VB.NET, but Microsoft only heard from the vocal minority who felt otherwise. And so a large number of VB programmers cling to VB 6. As Platt puts it, But [...]

Visual Basic and coyotes

Published on 2012-06-08 10:16:57

Where else to find me

Published on 2012-06-07 05:54:31

Here are some places I hang out besides this blog: Twitter Google+ Some things I’ve written: Software and articles about software Academic articles on math and statistics And some interviews I done: Microsoft Channel 9 Singularity Magazine Strongly Connected Components My email address is my last name at my domain name.

Where else to find me

Published on 2012-06-07 05:54:31

Small data

Published on 2012-06-06 06:59:08

Big data is getting a lot of buzz lately, but small data is interesting too. In some ways it’s more interesting. Because of limit theorems, a lot of things become dull in the large that are more interesting in the small. When working with small data sets you have to accept that you will very often [...]

C. S. Lewis on modeling

Published on 2012-06-05 07:00:42

From The Discarded Image by C. S. Lewis: The great masters do not take any Model quite so seriously as the rest of us. They know that it is, after all, only a model, possibly replaceable. Related posts: Amputating reality Just an approximation Advantages of crude models

Alan Turing and a trig puzzle

Published on 2012-06-04 19:42:56

Here’s a puzzle based on a passing remark in Andrew Hodges’ biography of Alan Turing. Hodges says that in 1927, Alan Turing, then 15 years old, discovered the Taylor series for arctangent “starting from the trigonometrical formula for tan(x/2).” Deriving the series could be a homework exercise in a calculus class, but Turing discovered the series without [...]

Calculating pi with AGM and mpmath

Published on 2012-06-03 13:57:51

This post gives an algorithm based on the arithmetic-geometric mean that rapidly converges to pi. I’ll use it to illustrate multiple precision arithmetic using Python’s mpmath module. Given two non-negative numbers a and b, their arithmetic mean is (a + b)/2 and their geometric mean is √(ab). Suppose you start with two non-negative numbers and take [...]

Post minimalism

Published on 2012-06-03 08:22:50

I’m suspicious of terms that start with “post-”. Often these terms are pretentious and inaccurate. When someone says, for example, that we’ve moved into a post-X era, they often mean that they didn’t like X and would like to think it’s gone. Despite my misgivings about post-this and post-that, I smiled the other day when I [...]

Humbled by a debugging book

Published on 2012-06-02 08:00:07

I started developing software for Windows in 1995, but I hardly know anything about Windows. I feel like my understanding of Windows peaked around the turn of the millennium and has declined since. I was reminded of the depth of my ignorance by a new book I received recently, Inside Windows Debugging. This book goes way [...]

When a good author writes a bad book

Published on 2012-06-01 07:45:58

The other day I read a terribly bland book by an author I’ve previously enjoyed. (I’d rather not name the book or the author.) The book was remarkably unremarkable. It reminded me that even the best strike out now and then. You have to evaluate someone by their best work, not their worst. If someone produces [...]

Writing software for someone else

Published on 2012-05-30 07:00:39

One of the differences between amateur and professional software development is whether you’re writing software for yourself or for someone else. It’s like the difference between keeping a journal and being a journalist. People who have only written software for their own use have no idea how much work goes into writing software for others. You [...]

Free Bach recordings

Published on 2012-05-29 16:20:03

James Kibbie has recorded Bach’s complete organ works and Kimiko Ishizaka has recorded his Goldberg Variations. Both artists have made their recordings free for download.

Why read and write tech books?

Published on 2012-05-28 14:40:52

Now that we have Google, countless blogs, and Stack Overflow, why should anyone buy technical books? And why should anybody write them? Charles Petzold’s answer is that books provide a narrative in a way that the web cannot. Books about programming have certainly become less essential over the past 15 years or so. … The Web has [...]

Unix doesn’t follow the Unix philosophy

Published on 2012-05-25 07:25:45

The Unix philosophy is a noble idea, but even Unix doesn’t follow it too closely. The Unix philosophy, as summarized by Doug McIlroy, says Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface. Here is an example from James [...]

First changes to a new computer

Published on 2012-05-24 07:00:26

Here are the first three changes I make to a new computer. Remap Caps Lock to be a control key. Delete all icons from the desktop. Mute the sound. Related posts: Why and how to remap Caps Lock (Windows, Linux, and Mac) Deleting the Windows recycle bin icon

The Book of Inkscape

Published on 2012-05-23 18:57:40

When I first started using Inkscape, I read Inkscape: Guide to a Vector Drawing Program by Tavmjong Bah, 3rd edition. It’s now in its 4th edition, which I have not seen. I received a copy of The Book of Inkscape by Dmitry Kirsanov recently, and it looks like the book I would have preferred to start [...]

Should you walk or run in the rain?

Published on 2012-05-23 07:00:01

One of the problems in X and the City, a book I mentioned the other day, is deciding whether you’ll get wetter by walking or running in the rain. The author takes several factors into account and models the total amount of water a person absorbs as This assumes a person is essentially a rectangular box of [...]

Using SciPy with IronPython

Published on 2012-05-21 21:26:31

Three years ago I wrote a post about my disappointment using SciPy with IronPython. A lot has changed since then, so I thought I’d write a short follow-up post. To install NumPy and SciPy for use with IronPython, follow the instructions here. After installation, NumPy works as expected. There is one small gotcha with SciPy. To use [...]

The 1970s

Published on 2012-05-21 10:33:06

Here’s a perspective on the 1970s I found interesting: The decade was so embarrassing that climbing out of the ’70s was a proud achievement. The 1970s were America’s low tide. Not since the Depression had the country been so wracked with woe. Never — not even during the Depression — had American pride and self-confidence plunged [...]

Differential Equations and the City

Published on 2012-05-19 16:29:23

This afternoon I got a review copy of X and the City: Modeling Aspects of Urban Life by John A. Adam. It’s a book about mathematical model, taking all its examples from urban life: public transportation, growth, pollution, etc. I’ve only skimmed through the book so far, but it looks like most of the applications involve [...]

Castles and quantum mechanics

Published on 2012-05-17 21:49:19

How are castles and quantum mechanics related? One connection is rook polynomials. The rook is the chess piece that looks like a castle, and used to be called a castle. It can move vertically or horizontally, any number of spaces. A rook polynomial is a polynomial whose coefficients give the number of ways rooks can be arranged [...]

Mars, magic squares, and music

Published on 2012-05-16 06:59:04

About a year ago I wrote about Jupiter’s magic square. Then yesterday I was listening to the New Sounds podcast that mentioned a magic square associated with Mars. I hadn’t heard of this, so I looked into it and found there were magic squares associated with each of solar system bodies known to antiquity (i.e. [...]

Machine Learning in Action

Published on 2012-05-15 08:23:14

A couple months ago I briefly reviewed Machine Learning for Hackers by Drew Conway and John Myles White. Today I’m looking at Machine Learning in Action by Peter Harrington and comparing the two books. Both books are about the same size and cover many of the same topics. One difference between the two books is choice [...]

Criteria for a computing setup

Published on 2012-05-14 06:05:36

“My setup” articles have become common. These articles list the hardware and software someone uses, usually with little explanation. The subtext is often the author’s commitment to the Apple brand or to open source, to spending money on the best stuff or to avoid spending money on principle. I don’t find such articles interesting or [...]

Solutions to knight’s random walk

Published on 2012-05-10 07:10:50

My previous post asked this question: Start a knight at a corner square of an otherwise-empty chessboard. Move the knight at random by choosing uniformly from the legal knight-moves at each step. What is the mean number of moves until the knight returns to the starting square? There is a mathematical solution that is [...]

A knight’s random walk

Published on 2012-05-08 19:33:51

Here’s a puzzle I ran across today: Start a knight at a corner square of an otherwise-empty chessboard. Move the knight at random by choosing uniformly from the legal knight-moves at each step. What is the mean number of moves until the knight returns to the starting square? There’s a slick mathematical solution that I’ll give later. You [...]

Web architecture

Published on 2012-05-08 07:00:40

Robert “Uncle Bob” Martin argues that an application’s purpose should determine its architecture; its delivery mechanism should not. If you look at an architectural drawing of a church, for example, you can tell it’s a church. But if you look at an architectural drawing of a web application, the fact that it’s a web application [...]

How do you know when someone is great?

Published on 2012-05-07 09:39:06

Roger Peng asks a good question on his blog this morning: How would you know if someone is great at data analysis? He says that while he has worked with some great data analysts, the nature of their work is that it’s hard to evaluate the work of someone you don’t know personally. And as [...]

An algebra problem from 1798

Published on 2012-05-05 08:20:21

The Lady’s Diary was a popular magazine published in England from 1704 to 1841. It contained mathematical puzzles such as the following, published in 1798. What two numbers are those whose product, difference of their squares, and the ratio or quotient of their cubes, are all equal to each other? From Benjamin Wardhaugh’s new book A Wealth [...]

Beer with a confidence interval

Published on 2012-05-04 08:18:39

Medalla is a Puerto Rican beer. On the side of a can it says Alcohol by volume over 4%, not more than 6%. I’d never seen a beer give a confidence interval for its alcohol content. I’d only seen point estimates before. For example, Budweiser announces that its beer contains 5% alcohol by volume. Just 5%, no [...]

Visiting Puerto Rico

Published on 2012-05-04 07:16:30

I’ve been in San Juan this week, visiting the University of Puerto Rico. I’ve been here several times before, but here are a few things I noticed about Puerto Rico on this trip. Coffee: Coffee means espresso here; I haven’t seen it brewed any other way. And it’s cheap. At UPR, a 4 oz pocillo is [...]

Python as a Lisp dialect

Published on 2012-05-03 06:55:11

From Peter Norvig: Basically, Python can be seen as a dialect of Lisp with “traditional” syntax … Python supports all of Lisp’s essential features except macros, and you don’t miss macros all that much because it does have eval, and operator overloading, and regular expression parsing, so some — but not all — of the use [...]

Reading historical math

Published on 2012-05-02 13:58:34

I recently received review copies of two books by Benjamin Wardhaugh. Here I will discuss How to Read Historical Mathematics. The other book is his anthology of historical popular mathematics which I intend to review later. Here is the key passage, located near the end of How to Read Historical Mathematics, for identifying the author’s perspective. But [...]

Big data is easy

Published on 2012-05-01 09:16:12

Big data is easy; big models are hard. If you just wanted to use simple models with tons of data, that would be easy. You could resample the data, throwing some of it away until you had a quantity of data you could comfortably manage. But when you have tons of data, you want to take advantage [...]

Traveling salesman art

Published on 2012-05-01 07:00:24

Bill Cook sent me a file yesterday that renders the Endeavour photo on my blog as the solution to a 66,290-city Traveling Salesman problem. His iPhone app Concord TSP chose 66,290 points and then solved for the shortest path connecting these points, a feat that would have strained a supercomputer a few years ago. [...]

Conforming for tenure

Published on 2012-04-30 13:00:31

From AnnMaria De Mars’ most recent blog post: Recently, a young person told me that I could hold to my principles about the importance of my family, honesty and equality — and any of a hundred other things because I had “made it”. This troubled me. It troubles me when I hear the same thing [...]

Open source and pride

Published on 2012-04-28 06:38:43

Liz Quilty explains how becoming an expert in open source software changed her life. [I was a] high school dropout, I had no education, I was nobody. I’d made some poor choices, and I think at this point suddenly I was known for my knowledge rather than for my poor choices. And so it was quite [...]

A tip on using a French press

Published on 2012-04-27 08:02:49

When I first bought a French press, the instructions said to pour hot but not boiling water over the coffee. They were emphatic about what the temperature should not be, but vague about what it should be. (Boiling water extracts oils that you’d rather leave in the grounds; water a little cooler brings out [...]

How variable are percentiles?

Published on 2012-04-27 06:33:15

Suppose you’re trying to study the distribution of something by simulation. The average of your simulation values gives you an estimate of the mean value of the thing you’re simulating. Next you want to have an idea how much the thing you’re simulating varies. You estimate the percentiles of your distribution by the percentiles of your [...]

Simmer reading list

Published on 2012-04-26 07:00:52

One of my friends mentioned his “simmer reading” yesterday. It was a typo — he meant to say “summer” — but a simmer reading list is interesting. Simmer reading makes me think of a book that stays on your nightstand as other books come and go, like a pot left to simmer on the back burner [...]

The cult of average

Published on 2012-04-25 06:45:48

Shawn Achor comments on “the cult of the average” in science. So one of the very first things we teach people in economics and statistics and business and psychology is how, in a statistically valid way, do we eliminate the weirdos. How do we eliminate the outliers so we can find the line of best fit? [...]

Chaotic versus random

Published on 2012-04-24 07:00:52

From John D. Barrow’s chapter in Design and Disorder: The standard folklore about chaotic systems is that they are unpredictable. They lead to out-of-control dinosaur parks and out-of-work meteorologists. … Classical … chaotic systems are not in any sense intrinsically random or unpredictable. They merely possess extreme sensitivity to ignorance. Any initial uncertainty in our knowledge of [...]

100x better approach to software?

Published on 2012-04-23 08:20:56

Alan Kay speculates in this talk that 99% or even 99.9% of the effort that goes into creating a large software system is not productive. Even if the ratio of overhead and redundancy to productive code is not as high as 99 to 1, it must be pretty high. Note that we’re not talking here about [...]

Random is as random does

Published on 2012-04-19 09:10:45

What is randomness? Nobody knows, or at least there’s no consensus. Everybody has some vague ideas what randomness is, but when you dig into it deeply enough you find all kinds of philosophical quandaries. If you’d like a taste of the subtleties, you could start by reading one of Gregory Chaitin’s books. Or chew on [...]

Just what do you mean by “number”?

Published on 2012-04-18 16:10:25

Tom Christiansen gave an awesome answer to the question of how to match a number with a regular expression. He begins by clarifying what the reader means by “number”, then gives answers for each. Is −0 a number? How do you feel about √−1? Is ⅝ or ⅔ a number? Is 186,282.42±0.02 miles/second one number — or is it [...]

Eat, drink, and be merry

Published on 2012-04-18 08:42:34

Almost every bit of health advice I’ve heard has been contradicted. Should you eat more carbs or fewer carbs? More fat or less fat? Take vitamin supplements or not? It reminds me of this clip from Sleeper in which Woody Allen wakes up after 200 years of suspended animation. Offhand I can only think of a [...]

Read history and fly an airplane

Published on 2012-04-17 21:49:05

The “About the Author” page at the end of Programming in Emacs Lisp says Robert J. Chassell … has an abiding interest in social and economic history and flies his own airplane. I love the child-like element of that bio. I could just imagine a kid saying “When I grow up, I want to read about history [...]

No Silver Bullet

Published on 2012-04-17 14:25:03

Mike Swaim gave a presentation today entitled No Silver Bullet, an allusion to Fred Brook’s classic essay by the same title. You can download the slides here. Mike discusses the pros and cons of the following software development techniques: High level languages Object oriented programming Declarative languages Functional programming Data oriented design Metaprogramming Static typing Duck typing Garbage collection Allocating on the stack Tail calls Resource acquisition is [...]

Superheroes of the Round Table

Published on 2012-04-17 07:00:25

The other day I was browsing the Rice library and ran across a little book called “Superheroes of the Round Table: Comics Connections to Medieval and Renaissance Literature.” It’s about how literature has influenced comic books, and how comic books shed light on literature. I don’t know much about comic books, or about medieval and renaissance [...]

Random number sequence overlap

Published on 2012-04-16 13:17:56

Mike Croucher asked the following question on his blog. Suppose you draw M sequences of random numbers of length N from a random number generator. What is the probability that they will overlap? Assumes your random number generator is a cyclical list of p unique integers. Each draw picks a random starting point in the cycle [...]

Dart programming language design

Published on 2012-04-14 14:41:09

Gilad Bracha’s presentation on Dart is interesting even if, like me, you do not intend to learn Dart. He has some good one-liners, especially digs at JavaScript, and some interesting ideas about programming language design. (JavaScript comes up frequently in presentation because of its popularity and because Dart compiles to JavaScript.) Application programmers, unless they’ve committed [...]

Santa Claus was just the tip of the iceberg

Published on 2012-04-14 07:58:37

From Skippy Dies: Gradually the awful truth dawns on you that Santa Claus was just the tip of the iceberg — that your future will not be the rollercoaster ride you’d imagined, that the world occupied by your parents, the world of washing the dishes, going to the dentist, weekend trips to the DIY superstore to [...]

Coffee posts

Published on 2012-04-13 07:00:40

Five coffee-related blog posts: A little coffee on the prairie A tale of two espresso machines Why drugs often list headache as a possible side-effect Four simple devices I prefer Distribution of time people spend in coffee shops

D programming language

Published on 2012-04-12 08:15:35

Until last week I’d barely heard of the D programming language. Then I had a chance to meet Walter Bright who designed the language in 1999. I also met Andrei Alexandrescu who has been collaborating on the design of D since 2006. Both gave talks on D at Lang.NEXT. Walter Bright’s talk was an overview of [...]

C++ at Facebook

Published on 2012-04-11 13:52:34

Andrei Alexandrescu said in a panel discussion last week that when he joined Facebook two years ago, maybe 90% of the programmers wrote PHP and 10% C++. Now there are roughly as many C++ programmers as PHP programmers. One reason Facebook is shifting more work to C++ is to reduce operating costs such as power [...]

C++ Renaissance

Published on 2012-04-11 08:35:30

Dynamic language developers who are concerned about performance end up writing pieces of their applications in C++. So if you’re going to write C++ anyway, why not write your entire application in C++? Library writers develop in C++ so that their users won’t have to. That makes a lot of sense. But if you’re developing your [...]

Square root of people

Published on 2012-04-10 08:20:03

How do you infer the economic well-being of individuals from household income? At one extreme, you could just divide household income by the number of people in the household. This is naive because there are some economies of scale. It doesn’t take twice as much energy to heat a house for two people as a [...]

Classifier progress exaggerated?

Published on 2012-04-09 14:00:11

Yesterday Simply Statistics linked to a paper with the provocative title Classifier Technology and the Illusion of Progress. I’ve only skimmed the article so far, but here are a few sentences that stood out. In particular, simple methods typically yield performance almost as good as more sophisticated methods, to the extent that the difference in performance [...]

WinRT, Projections, and COM

Published on 2012-04-07 10:20:06

Martyn Lovell gave a great talk on the new Windows Runtime at Lang.NEXT this week. You know it’s going to be a good talk when the speaker uses the word “soporific” four seconds into the presentation. One of the ideas I found interesting was language projections, providing multiple programming languages idiomatic access to the lowest [...]

WinRT, Projections, and COM

Published on 2012-04-07 10:20:06

Having the first word

Published on 2012-04-06 22:15:50

From Too Big to Know: On the Net, the measure of one’s strength as an expert often is not that you have the final word on some topic but that you have the first word.

Having the first word

Published on 2012-04-06 22:15:50

From Too Big to Know: On the Net, the measure of one’s strength as an expert often is not that you have the final word on some topic but that you have the first word.

Writing software for space probes

Published on 2012-04-06 07:18:50

A few days ago I quoted Ron Garret on his experience debugging software running millions of miles away. Since then I discovered a video of a talk Garret gave at Google a few weeks ago. He talks about remote debugging toward the end of his presentation, but most of his talk is about how NASA [...]

Writing software for space probes

Published on 2012-04-06 07:18:50

Fractional integration

Published on 2012-04-05 17:08:14

Define the integration operator I by so I f is an antiderivative of f. Define the second antiderivative I2 by applying I to f twice: It turns out that To see this, notice that both expressions for I2 are equal when x = a, and they have the same derivative, so they must be equal everywhere. Now define I3 by [...]

Fractional integration

Published on 2012-04-05 17:08:14

Users will tolerate a lot to get their work done

Published on 2012-04-04 22:18:18

Suppose users have a choice of two software applications. Application #1: Beautiful user interface, well documented, robust. It does 99% of what they need in order to get their work done, but they don’t know how to do the remaining 1%. Application #2: Ugly, poorly documented, crashes routinely, but it does 100% of what they need. Users will [...]

Users will tolerate a lot to get their work done

Published on 2012-04-04 22:18:18

Irrelevance of earlier dreams

Published on 2012-04-03 11:32:00

From Daniel Lemire’s latest blog post: I find that this irrelevance of my earlier dreams is a common pattern throughout my life. My younger self was dreaming about having things and being someone. He thought this would bring happiness. He was wrong.

Irrelevance of earlier dreams

Published on 2012-04-03 11:32:00

a < b < c

Published on 2012-04-03 07:20:25

In Python, and in some other languages, the expression a < b < c is equivalent to a < b and b < c. For example, the following code outputs “not increasing.” a, b, c = 3, 1, 2 if a < b < c: print "increasing" else: print "not increasing" Now consider [...]

a < b < c

Published on 2012-04-03 07:20:25

Large-scale JavaScript

Published on 2012-04-02 16:44:54

From a panel discussion at Lang.NEXT on cloud and web programming this afternoon. Erik Meijer: Are you saying you cannot write large programs in JavaScript? Anders Hejlsberg: No, you can write large programs in JavaScript. You just can’t maintain them.

Large-scale JavaScript

Published on 2012-04-02 16:44:54

Math languages vs. application languages

Published on 2012-04-02 08:00:36

Last Friday I posted on @SciPyTip a summary of why I like SciPy, the scientific programming library for Python. I’d rather do math in a general-purpose language than try to do general-purpose programming in a math language. Mathematical software is never purely mathematical. The math has to connect to something, and that’s where most of the programming [...]

Math languages vs. application languages

Published on 2012-04-02 08:00:36

tl;dr

Published on 2012-03-29 09:12:49

The slang “tl;dr” stands for “too long; didn’t read.” The context is often either a bad joke or a shallow understanding. What bothers me most about tl;dr is the mindset it implies, scanning everything but reading nothing. I find myself slipping into that mode sometimes. Skimming is a vital skill, but it can become so habitual [...]

tl;dr

Published on 2012-03-29 09:12:49

How Emacs influenced Ruby

Published on 2012-03-28 08:27:14

Ruby creator Yukihiro Matsumoto gave a presentation How Emacs changed my Life in which he explains how Emacs influenced him personally and how it influenced the programming language he created. Here is his summary: Emacs taught me freedom for software. Emacs taught me how to code. Emacs taught me the power of Lisp. Emacs taught me how to implement [...]

Numerous studies have confirmed …

Published on 2012-03-27 21:20:23

I was listening to a business book in my car this afternoon. A couple times it said Numerous studies have confirmed … and I couldn’t help but hear Several of my peers, who share my prejudices, were also able to do a multivariate regression and select a few variables out of hundreds to confirm the prevailing wisdom. Maybe the [...]

Polynomial determined by two inputs

Published on 2012-03-27 05:33:22

Suppose p(x) is a polynomial with integer coefficients. If all the coefficients are non-negative, I can tell you what p(x) is if you’ll tell me the value of p(x) at just two points. This sounds too good to be true. Don’t you need n+1 points to determine an nth degree polynomial? Not in this case. The [...]

Photo quiz: What’s this?

Published on 2012-03-25 14:52:34

What do think the object on the left is? (The chair is only in the photo for a sense of scale.) It’s the aluminum engine block from an ATV that was destroyed in the Bastrop wildfire last summer. Related post: Bastrop wildfire

Debugging code running 100 million miles away

Published on 2012-03-22 07:02:15

From Lisping at JPL: Debugging a program running on a $100M piece of hardware that is 100 million miles away is an interesting experience. Having a read-eval-print loop running on the spacecraft proved invaluable in finding and fixing the problem. The context of the quote was the author’s experience debugging Lisp software running on the Deep Space [...]

Numerical integration trick

Published on 2012-03-21 19:21:07

Suppose you want to evaluate the following integral: We’d like to do a change of variables to make the range of integration finite, and we’d like the transformed integral to be easy to evaluate numerically. The change of variables t = 1/x2 transforms the range of integration from (30, ∞) to (0, 1/900). I’ll explain where this [...]

Math is like the Hawaiian islands

Published on 2012-03-21 06:39:25

Keith Kendig compares math to the Hawaiian islands: Hawaii may look like a group of separate islands, but actually the islands are just the highest peaks of an immense, mostly-submerged mountain range. All that water hides their underlying connectedness, their oneness. Mathematics may similarly seem like an archipelago of different areas — geometry, analysis, topology, number [...]

SciPy integration misunderstanding

Published on 2012-03-20 19:56:15

Today I needed to compute an integral similar to this: I used the following SciPy code to compute the integral: from scipy.integrate import quad def f(x): return 0.01*x**-3 integral, error = quad(f, 1000, sp.inf, epsrel = 1e-6) print integral, error My intention was to compute the integral to 6 significant figures. (epsrel is a shortened form of epsilon [...]

Nicolas Bourbaki’s wedding invitation

Published on 2012-03-20 07:43:55

Nicolas Bourbaki was the collective pseudonym of a semi-secret group of French mathematicians, best known for the formal style of mathematics it promoted. The group insisted that Bourbaki was a real person, but only as a joke. The most recent Math Mutation podcast quotes a wedding invitation for Bourbaki. Monsieur Nicolas Bourbaki, Canonical Member of the Royal [...]

Easiest and hardest classes to teach

Published on 2012-03-19 21:31:15

I’ve taught a variety of math classes, and statistics has been the hardest to teach. The thing I find most challenging is coming up with homework problems. Most exercises are either blatantly artificial or extremely tedious. It’s hard to find moderately realistic problems that don’t take too long to work out. The course I’ve found easiest [...]

Software to slice bread

Published on 2012-03-18 12:55:38

In the dark ages of programming, functions acted on data. To slice your bread, you passed a bread data structure to a slice function: slice(bread); Then came object oriented programming. Instead of having an external function slice our bread, we would ask the bread to slice itself by calling the slice method on a bread object: bread.slice(); Obviously a [...]

Digital desk, analog desk

Published on 2012-03-13 07:00:29

Austin Kleon has an interesting idea for setting up a workspace: have a digital desk and an analog desk. I have two desks in my office — one is “analog” and one is “digital.” The analog desk has nothing but markers, pens, pencils, paper, index cards, and newspaper. Nothing electronic is allowed on that desk. That’s [...]

Misplaced decimal

Published on 2012-03-12 23:15:29

This evening I ran across a dialog that suggests that decimal notation is wrong. It happened when I started learning about decimals in school. I knew then that ten has one zero, a hundred has two, a thousand three, and so on. And then this teacher starts saying that tenth doesn’t have any zero, a hundredth [...]

iPad as hip flask

Published on 2012-03-10 21:09:29

I reread Paul Graham’s essay The Acceleration of Addictiveness after a friend quoted it in a blog post explaining why he is taking an indefinite hiatus from social media. I hadn’t noticed this gem in the footnotes when I first read Graham’s essay: Several people have told me they like the iPad because it lets them [...]

Monkeying with Bayes’ theorem

Published on 2012-03-09 13:01:17

In Peter Norvig’s talk The Unreasonable Effectiveness of Data, starting at 37:42, he describes a translation algorithm based on Bayes’ theorem. Pick the English word that has the highest posterior probability as the translation. No surprise here. Then at 38:16 he says something curious. So this is all nice and theoretical and pure, but as well [...]

Comedic genealogy

Published on 2012-03-08 09:00:07

Austin Kleon on imitation and originality: Johnny Carson tried to be Jack Benny but ended up Johnny Carson. David Letterman tried to copy Johnny Carson but ended up David Letterman. And Conan O’Brien tried to be David Letterman but ended up Conan O’Brien. In O’Brien’s words, “It is our failure to become our perceived ideal that [...]

Machine Learning for Hackers

Published on 2012-03-07 21:40:13

Drew Conway and John Myles White have a new book out, Machine Learning for Hackers. As the name implies, the emphasis is on exploration rather than mathematical theory. Lots of code, no equations. If you’re looking for a hands-on introduction to machine learning, maybe as a prelude to or complement to a more theoretical text, you’ll [...]

Shuffling Emacs windows

Published on 2012-03-07 20:42:25

Emacs lets you split your screen into windows, what other applications might call panels. This can be quite handy. However, I often want to move the windows around and I couldn’t find how to do that. I asked Xah Lee, he posted the question on G+, and Mark Hepburn answered with a pointer to code [...]

Clipboard history

Published on 2012-03-07 10:35:45

The Windows clipboard only remembers the most recent thing you copied [1]. This can be very disappointing. Maybe you cut a large block of text intending to paste it somewhere, but without thinking you cut something else, and then realize you’ve just wiped out your first cut. Here are a few possible alternatives for Windows, [...]

Weaponized code

Published on 2012-03-06 10:18:14

This morning someone asked me if I could “weaponize” his code, i.e. turn his research software into something robust enough for production. I like that term.

Weaponized code

Published on 2012-03-06 10:18:14

This morning someone asked me if I could “weaponize” his code, i.e. turn his research software into something robust enough for production. I like that term.

Approximating galaxies as spheres

Published on 2012-03-06 09:14:28

A couple days ago I compared different ways of approximating Earth and other ellipsoids by spheres. The earth is so nearly spherical that the difference in the approximations would only matter when you need fairly high accuracy. Elliptical galaxies, however, can be much more eccentric than Earth and so the difference in approximation approaches can [...]

Approximating galaxies as spheres

Published on 2012-03-06 09:14:28

Narcissus prime

Published on 2012-03-05 08:54:43

This morning Futility Closet posted the following. Repeat the string 1808010808 1560 times, and tack on a 1 the end. The resulting 15601-digit number is prime, and because it’s a palindrome made up of the digits 1, 8, and 0, it remains prime when read backward, upside down, or in a mirror. I used Mathematica [...]

Narcissus prime

Published on 2012-03-05 08:54:43

Approximating Earth as a sphere

Published on 2012-03-04 16:12:06

Isaac Newton suggested in 1687 that the earth is not a perfectly round sphere but rather an ellipsoid, and he was right. But since our planet is roughly a sphere, it’s often useful to approximate it by a sphere. So if you’re going to do that, what radius do you use? More generally, what radius [...]

Approximating Earth as a sphere

Published on 2012-03-04 16:12:06

Life off the clock

Published on 2012-03-02 05:55:54

There was a lot of work to do a few generations ago, but the work wasn’t regulated by a clock. With the growth of industrial capitalism during the post-Civil War years, more and more Americans were feeling pressure to be “on time.” (The phrase itself was a colloquialism which did not appear until the 1870s.) The [...]

Life off the clock

Published on 2012-03-02 05:55:54

Comparing R to smoking

Published on 2012-02-29 14:46:29

Francois Pinard comparing the R programming language to smoking: Using R is a bit akin to smoking. The beginning is difficult, one may get headaches and even gag the first few times. But in the long run, it becomes pleasurable and even addictive. Yet, deep down, for those willing to be honest, there is something not [...]

Comparing R to smoking

Published on 2012-02-29 14:46:29

Opposite of YAGNI

Published on 2012-02-29 08:45:20

There’s a motto in agile software development that says “You aren’t going to need it,” YAGNI. The idea is that when you’re tempted to write some code based on speculation of future use, don’t do it. (I go into this a little deeper here.) Although “you aren’t going to need it” is a good principle for [...]

Opposite of YAGNI

Published on 2012-02-29 08:45:20

Gilbert & Sullivan on Leap Day

Published on 2012-02-29 06:25:31

For some ridiculous reason, to which, however, I’ve no desire to be disloyal, Some person in authority, I don’t know who, very likely the Astronomer Royal, Has decided that, although for such a beastly month as February, twenty-eight days as a general rule are plenty, One year in every four, its days shall be reckoned as nine and [...]

Gilbert & Sullivan on Leap Day

Published on 2012-02-29 06:25:31

How to solve supposedly intractable problems

Published on 2012-02-28 07:06:35

Contrary to semi-educated belief, NP-complete problems are not necessarily intractable. Often such problems are intractable, but not always. If a problem is NP-complete, this means that there is no polynomial-time algorithm for solving the problem for the worst case, as the problem size grows, finding exact solutions, with certainty, as far as anyone knows. One way out of this (#5) is [...]

How to solve supposedly intractable problems

Published on 2012-02-28 07:06:35

It’s not what you cover

Published on 2012-02-27 21:01:51

Walter Lewin on teaching physics: What counts, I found, is not what you cover but what you uncover. Covering subjects in a class can be a boring exercise, and students feel it. Uncovering the laws of physics and making them see through the equations, on the other hand, demonstrates the process of discovery, with all its [...]

It’s not what you cover

Published on 2012-02-27 21:01:51

Stretched thin

Published on 2012-02-26 18:50:34

Here are a couple quotes on being stretched thin. From Bilbo Baggins in Lord of the Rings: I feel thin, sort of stretched, like butter, scraped over too much bread. From David Wells in God in the Wasteland: To stretch this far … modernity must necessarily be culturally thin. … It is a generic culture, this culture of the [...]

Audible confetti

Published on 2012-02-25 17:17:52

“Audible confetti” is a striking metaphor for distracting noise. Here’s the context where I ran across the phrase this morning: The public sphere, dominated as it is by the omnipresence of bureaucracy, systems of manufacturing, the machinery of capitalism, and the audible confetti spewing out of countless radios and televisions, makes it virtually impossible to think [...]

Julia random number generation

Published on 2012-02-22 21:48:00

Julia is a new programming language for scientific computing. From the Julia site: Julia is a high-level, high-performance dynamic programming language for technical computing, with syntax that is familiar to users of other technical computing environments. It provides a sophisticated compiler, distributed parallel execution, numerical accuracy, and an extensive mathematical function library. … I just started playing [...]

Playing with Eshell

Published on 2012-02-22 17:26:34

I’ve been trying out Eshell lately. It’s a shell implemented in Emacs Lisp. Here I’ll mention a few features I’ve found interesting. The command M-x shell lets you run a shell inside Emacs. This is quite handy, but it runs a different shell on each platform. For example, it might pull up bash on Linux and [...]

Texas accents

Published on 2012-02-22 12:55:13

The young lady who took my order at lunch today had a strong Texas accent. You might think this would be nothing unusual — I live in Texas — but it surprised me. Don’t Texans have Texas accents? Strictly speaking, yes, people in Texas speak like people in Texas. However, most people in Texas do not [...]

Care and treatment of singularities

Published on 2012-02-21 07:10:23

My favorite numerical analysis book is Numerical Methods that Work. In the hardcover version of the book, the title was impressed in the cover and colored in silver letters. Before the last word of the title, there was another word impressed but not colored in. You had to look at the cover carefully to see [...]

Monday morning math puzzle

Published on 2012-02-20 10:06:33

This morning Futility Closet mentioned that How common is this? In other words, what is the probability that a random set of digits ai will satisfy the following? How does the probability depend on n?

Thoughts on the new Windows logo

Published on 2012-02-17 19:09:57

I appreciate spare design, but the new Windows logo is just boring. Here’s the rationale for the new logo according to The Windows Blog: But if you look back to the origins of the logo you see that it really was meant to be a window. “Windows” really is a beautiful metaphor for computing and with the [...]

What’s your backplane?

Published on 2012-02-17 09:41:51

When I hear someone I respect rave about a software tool I’ll take a look at it. When I do, it often leaves me cold and I wonder how they could think it’s so great. Is this person just easily impressed? I think I understand now why this happens. Tools are used in a context, and [...]

Would you rather serve a market or a boss?

Published on 2012-02-17 07:39:58

Here’s an idea to chew on. Hayek argues that you either have to serve a market or a boss, and that the former is preferable. Man in a complex society can have no choice but between adjusting himself to what to him must seem the blind forces of the social process and obeying the orders of [...]

Book review: Functional Analysis

Published on 2012-02-16 10:21:37

Functional Analysis by Elias Stein and Rami Shakarchi is a fast-paced book on functional analysis and related topics. By page 60, you’ve had a decent course in functional analysis and you’ve got 360 pages left. This book is the last in a series of four volumes based on a series of lectures that began at Princeton [...]

Facebook meme parody

Published on 2012-02-16 09:57:37

The current fad on Facebook is 2 x 3 photo arrays. They have a profession name in the tile and the photos have captions like “What society thinks I do,” “What my Mom thinks I do,” “What I think I do,” etc. Here’s my favorite so far: larger image

Using C# like a scripting language

Published on 2012-02-16 07:08:36

Clift Norris wrote a clever little batch file csrun.bat several years ago. I thought I’d posted it here, but apparently not. If you have a C# program in foo.cs, you can type csrun foo.cs to compile and run the program. The batch file doesn’t do much at all, but it might change how you think about [...]

LISP, CHAP, and FLOP

Published on 2012-02-15 20:01:24

From the foreword to The Seasoned Schemer: “LISP” originally stood for “LISt Processing.” By the same token, I suppose that the C programming language could have been called CHAP (for “CHAracter Processing”) and Fortran could have been called FLOP (for “FLOating-point processing”). Guy L Steele Jr.

Teach yourself Fourier analysis in two weeks

Published on 2012-02-15 14:32:39

From William Thompson (Lord Kelvin), 1840: I had become filled with the utmost admiration for the splendor and poetry of Fourier. … I asked [John Pringle] Nichol if he thought I could read Fourier. He replied ‘perhaps.’ He thought the book a work of most transcendent merit. So on the 1st of May … I took [...]

Dot, cross, and quaternion products

Published on 2012-02-15 07:02:46

This post will show that quaternion product = cross product – dot product. First, I’ll explain what quaternions are, then I’ll explain what the equation above means. The complex numbers are formed by adding to the real numbers a special symbol i with the rule that i2 = -1. The quaternions are similarly formed by adding to the [...]

Irreproducible research on 60 Minutes

Published on 2012-02-14 08:12:04

If your research cannot be reproduced, you might end up on 60 Minutes. Two days ago the new show ran a story about irreproducible research at Duke. You can find the video clip here. I believe the 60 Minutes piece was somewhat misleading. It focused on data manipulation and implied that the controversial results followed from [...]

Maybe C++ hasn’t jumped the shark after all

Published on 2011-07-06 06:36:40

A couple years ago I wrote a blog post Has C++ jumped the shark? I wondered how many people would care about the new C++ standard by the time it came out. I doubted that it would matter much to me personally. … if something is hard to do in C+

Golden Carnival of Mathematics

Published on 2011-07-05 20:16:21

Welcome to the 79th edition of the Carnival of Mathematics. By tradition, each edition begins with a bit of trivia about the number of the carnival. Gold has atomic number 79, so this is the golden edition. There is an older tradition of calling 25t

Sorting

Published on 2011-07-04 15:25:45

From Knuth’s book Sorting and Searching: Computer manufacturers of the 1960’s estimated that more than 25 percent of the running time of their computers was spent on sorting, when all their customers were taken into account. In fact, ther

Ray Charles sings America the Beautiful, 1972

Published on 2011-07-04 08:44:05

From the world, to the world

Published on 2011-07-01 08:02:29

Edmund Harriss describes an interesting pattern he sees in mathematics and constructivist art in his interview on Strongly Connected Components. For most of history, mathematics and art have been fairly direct abstractions of physical reality. Then i

Friday miscellany

Published on 2011-07-01 05:06:32

Diagrams Tech company org charts Beer diagram Education Advantages of printed textbooks 16 things a CS major should do before graduating Math What Alan Turing did for his PhD 13 surprising Fibonacci appearances Computing The implementation of functio

Calling C++ from R

Published on 2011-06-30 08:59:55

This post relates my experience with calling C++ from R by writing an R module from scratch and by the inline module. The most reliable way to speed up R code is to take it out of R. I’ve looked at various tricks for speeding up R code and non

Doubly periodic functions

Published on 2011-06-29 12:36:05

Functions like sine and cosine are periodic. For example, sin(x + 2πn) = sin(x) for all x and any integer n, and so the period of sine is 2π. But what happens if you look at sine or cosine as functions of a complex variable? They’re still per

It takes more than a better mouse trap

Published on 2011-06-29 07:00:26

Emerson was wrong. The world will not beat a path to your door just because you build a better mouse trap. No busy, overstressed, fire-putting-out, content-with-the-product-they-have-now person really wants to hear from you. Even when you do build a

It takes more than a better mouse trap

Published on 2011-06-29 07:00:26

High-brow limericks

Published on 2011-06-28 06:49:32

Philosophy Said Plato: “These things that we feel Are not ontologically real, But just the excresence Of numinous essence Our senses can never reveal.” via Futility Closet Calculus The integral z-squared dz From one to the cube root of 3 Times th

High-brow limericks

Published on 2011-06-28 06:49:32

Weekend miscellany

Published on 2011-06-25 16:54:39

Average New York City sky color every five minutes Photography tips for idiots The biggest changes in C++ 2011 Why writing software is not like engineering First world problem rap

Weekend miscellany

Published on 2011-06-25 16:54:39

Average New York City sky color every five minutes Photography tips for idiots The biggest changes in C++ 2011 Why writing software is not like engineering First world problem rap

Fifteen interviews

Published on 2011-06-24 08:53:26

Seven people I have interviewed: Rick Richter, CIO of Food for the Hungry Eric Floehr, owner of ForecastWatch Frederick Brooks, computer pioneer and author Robert Ghrist, applied topologist Cliff Pickover, mathematician and author Dan Bricklin, soft

Fifteen interviews

Published on 2011-06-24 08:53:26

Square root interview question

Published on 2011-06-23 08:48:03

Imagine some of the answers you might get to “What is the square root of 101?” First, three answers that suggest an interviewee is not strong with math. What’s a square root? You gotta calculator? 101 doesn’t have a square

Square root interview question

Published on 2011-06-23 08:48:03

Platform lock-in

Published on 2011-06-22 07:05:57

From Baron Schwartz speaking at the O’Reilly Media MySQL Conference: We talk about proprietary vendor lock-in, but in many cases the reality is that anyone who uses any platform, even an open source one, ends up being locked-in to some extent.

Platform lock-in

Published on 2011-06-22 07:05:57

How to fit an elephant

Published on 2011-06-21 07:00:47

John von Neumann famously said With four parameters I can fit an elephant, and with five I can make him wiggle his trunk. By this he meant that one should not be impressed when a complex model fits a data set well. With enough parameters, you can fit

How to fit an elephant

Published on 2011-06-21 07:00:47

Software under-represents reality

Published on 2011-06-20 09:51:43

From Jaron Lanier: I love software, but software always under-represents reality. Reality has this depth to it and potential for surprise and subtlety that you just can’t get from software. Related posts: The bipolar Internet Underwhelmed with

Software under-represents reality

Published on 2011-06-20 09:51:43

An unexpected Father’s Day card

Published on 2011-06-19 21:57:41

As an undergraduate I was part of an honors program called Dean’s Scholars. I have a T-shirt from a Dean’s Scholars reunion several years ago that my wife doesn’t appreciate as much as I do. She thinks I shouldn’t wear it just

An unexpected Father’s Day card

Published on 2011-06-19 21:57:41

A surprise with Emacs and Office 2007

Published on 2011-06-18 10:38:10

I had a little surprise when I tried to open an Excel file from Emacs. I was using dired, a sort of file explorer inside Emacs. I expected one of two things to happen. Maybe Emacs would know to launch the file using Excel. Or maybe it would open the

A surprise with Emacs and Office 2007

Published on 2011-06-18 10:38:10

Weekend miscellany

Published on 2011-06-18 06:19:33

Work The risk of working hard Why people want you to march to the beat of their drummer Software development The future of C++ Optimizing higher-level programming languages Math Mathematical background for computer science Course in pseudorandomness

Weekend miscellany

Published on 2011-06-18 06:19:33

Write the other way

Published on 2011-06-16 09:46:38

This notebook made me think of the quote from William Carlos Williams: “If they give you lined paper, write the other way.”

Write the other way

Published on 2011-06-16 09:46:38

This notebook made me think of the quote from William Carlos Williams: “If they give you lined paper, write the other way.”

Impure math

Published on 2011-06-15 11:57:35

When Samuel Hansen said in his interview “You’re not a pure mathematician” I agreed without thinking, but later the statement bothered me a little. I know what he meant: considering the two categories of pure math and applied math,

Impure math

Published on 2011-06-15 11:57:35

Manga guides to physics and the universe

Published on 2011-06-15 07:03:18

I recently received review copies of the Manga Guides to physics and the universe. These made a better impression than the relativity guide that I reviewed earlier. The guide to physics has been out for a while. The guide to the universe comes out Ju

Manga guides to physics and the universe

Published on 2011-06-15 07:03:18

Interview on Strongly Connected Components

Published on 2011-06-14 14:06:57

Samuel Hansen interviews me in the latest episode of his podcast Strongly Connected Components.

Interview on Strongly Connected Components

Published on 2011-06-14 14:06:57

Samuel Hansen interviews me in the latest episode of his podcast Strongly Connected Components. I’ve enjoyed listening to Samuel’s podcast since it started a couple years ago. Here’s a list of other mathematical podcasts.

Why do C++ folks make things so complicated?

Published on 2011-06-14 06:45:16

This morning Miroslav Bajtoš asked “Why do C++ folks make things so complicated?” in response to my article on regular expressions in C++. Other people have said something similar yesterday. My response has two parts: Why I believe C++

Why do C++ folks make things so complicated?

Published on 2011-06-14 06:45:16

This morning Miroslav Bajtoš asked “Why do C++ folks make things so complicated?” in response to my article on regular expressions in C++. Other people asked similar questions yesterday. My response has two parts: Why I believe C++ libr

Have you saved a milliwatt today?

Published on 2011-06-13 09:41:30

Research In Motion (RIM) is best known for making the BlackBerry. In the early days of the company, RIM focused on reducing the BlackBerry’s power consumption. The engineers put up a sign: Have you saved a milliwatt today? This was a specific,

Have you saved a milliwatt today?

Published on 2011-06-13 09:41:30

Bundled versus unbundled version history

Published on 2011-06-13 09:01:40

The other day I said to a colleague that an advantage to LaTeX over Microsoft Word is that it’s easy to version LaTeX files because they’re just plain text. My colleague had the opposite view. He said that LaTeX was impossible to version

Bundled versus unbundled version history

Published on 2011-06-13 09:01:40

Weekend miscellany

Published on 2011-06-11 07:43:39

Photography Photos from the International Space Station Culture Is there a new geek anti-intellectualism? Statistics Bad statistics is now a crime Programming Interview with Clojure author Rich Hickey How I Failed, Failed, and Finally Succeeded at Le

Weekend miscellany

Published on 2011-06-11 07:43:39

Simpler version of Stirling’s approximation

Published on 2011-06-10 08:48:53

Here’s an approximation for n! similar to Stirling’s famous approximation. I ran into this reading A View from the Top by Alex Iosevich. It is less accurate than Stirling’s formula, but has three advantages. It contains the highes

Simpler version of Stirling’s approximation

Published on 2011-06-10 08:48:53

Mental context switches are evil

Published on 2011-06-09 07:00:37

This week I’ve run across two examples of technical strategies to reduce mental context switches. The first example is Pete Kruckenberg’s story of why his team chose to develop a web application using node.js even though he had extensive

Mental context switches are evil

Published on 2011-06-09 07:00:37

Stand-alone scientific code

Published on 2011-06-07 07:54:38

Sometimes you need one or two scientific functions not included in your programming environment. For a number of possible reasons, you do not want to depend on an external library. For example, maybe you don’t want to take the time to evaluate

Stand-alone scientific code

Published on 2011-06-07 07:54:38

Destructive capacity of individuals and states

Published on 2011-06-07 05:38:53

From Modern Times: The destructive capacity of the individual, however vicious, is small; of the state, however well-intentioned, almost limitless.

Destructive capacity of individuals and states

Published on 2011-06-07 05:38:53

From Modern Times: The destructive capacity of the individual, however vicious, is small; of the state, however well-intentioned, almost limitless.

Friday miscellany

Published on 2011-06-03 10:00:31

Eclectic Vintage advertising The evolution of email Solving the wrong problem Alternative medicines and placebos Truth stranger than fiction Larry Ellison suing neighbors over his view Towing icebergs Math Elementary Applied Topology draft textbook I

Friday miscellany

Published on 2011-06-03 10:00:31

What it means to understand an equation

Published on 2011-06-02 19:27:54

From Nobel physicist Paul Dirac: I understand what an equation means if I have a way of figuring out the characteristics of its solution without actually solving it.

What it means to understand an equation

Published on 2011-06-02 19:27:54

From Nobel physicist Paul Dirac: I understand what an equation means if I have a way of figuring out the characteristics of its solution without actually solving it.

Collatz 3n + 1 conjecture solved

Published on 2011-06-01 20:35:31

Gerhard Opfer has posted a paper that claims to resolve the famous Collatz conjecture. Start with a positive number n and repeatedly apply these simple rules: If n = 1, stop. If n is even, divide n by 2. If n is odd, multiply n by 3 and add 1. In 1

Clutter-discoverability trade-off

Published on 2011-06-01 06:51:19

There’s a tension between presenting a user an uncluttered interface and helping the user discover new features. This post will begin by discussing two extreme examples. On the cluttered but discoverable end of the spectrum is Microsoft Word 20

Chainsaw on a rope swing

Published on 2011-05-31 08:01:10

Here’s something I wish I’d understood early in my career. From Merlin Mann: If a project doesn’t have an owner, it’s like a chainsaw on a rope swing. Why would anyone even go near that? Related posts: Priorities Project manag

What was the most important event of the 19th century?

Published on 2011-05-30 18:28:17

According to Richard Feynman, the most important event of the 19th century was the discovery of the laws of electricity and magnetism. From a long view of the history of mankind — seen from, say, ten thousand years from now — there can be

Friday miscellany

Published on 2011-05-27 10:41:33

Photography Long-exposure photos of planes taking off and landing Japan in the 1920s Pop culture Christianized paganism Software development Architecture of open source applications Statistics Principles of uncertainty Lessons from the Victorian data

Software architecture as a function of trust

Published on 2011-05-26 07:24:21

Discussions of software architecture give the impression that the only concern is the problem domain: how to structure a content management system, how to structure a word processor, etc. This leaves out the people who will be developing the software

Classifying errors

Published on 2011-05-25 21:45:28

In the latest episode of EconTalk, Russ Roberts mentions Jens Rasmussen’s classification of errors into three categories: slips, mistakes, and violations. So, a slip is: you just do something you immediately realize wasn’t what you meant

Advantages of crude models

Published on 2011-05-25 07:27:28

One advantage of crude models is that we know they are crude and will not try to read to much from them. With more sophisticated models, … there is an awful temptation to squeeze the lemon until it is try and to present a picture of the future whic

Sheet music, DNA, and source code

Published on 2011-05-23 09:38:59

Beginning musicians think that sheet music contains more information than it does. It’s all they can do to play the notes on the page. Only later do they realize that sheet music is at best a good approximation of what a composer has in mind. E

Manga Guide to Relativity

Published on 2011-05-21 09:37:52

A few days ago I got a review copy of The Manga Guide to Relativity. This is an English translation of a book first published in Japanese a couple years ago. I assume the intended audience, at least for the original Japanese edition, is familiar with

Friday miscellany

Published on 2011-05-20 09:13:41

Photography A Starry Night of Iceland 100 Incredible Views Out Of Airplane Windows Eiffel Tower Math Quaterninons and Quilts Mathematical dance moves Magic squares Dijkstra’s fusc function Ramanujan’s notebooks Music videos Mariachi Pink

3.5 ways to subscribe to this blog

Published on 2011-05-19 08:25:13

Here are three and a half ways to subscribe to this blog. RSS. If you’re unfamiliar with RSS, here’s a video explaining what it is and how to use it. The video makes a nice analogy. Visiting blogs is like going to Blockbuster for a video

How to subscribe to a Twitter account via RSS

Published on 2011-05-18 08:40:52

Twitter has recently made it more difficult to subscribe to accounts via RSS. This article that goes into the details of the problem and offers a solution. At least for now, you can construct a URL to a Twitter account RSS feed by starting with https

Writing software is harder than writing books

Published on 2011-05-17 07:00:03

According to computer scientist Donald Knuth, someone who has written numerous books, writing software is more difficult than writing books. The most important lesson I learned during the past nine years [1977 – 1986, when Knuth developed TeX] is t

New Twitter account: RLangTip

Published on 2011-05-16 09:43:06

I’m starting a new daily tip Twitter account: RLangTip. This account will have one regularly scheduled tip per day, Monday through Friday, on the R language and related topics. I’ll also throw in a few unscheduled tweets now and then. If

Bumblebee software

Published on 2011-05-16 07:56:52

Some say that aerodynamics can’t explain how a bumblebee flies. Perhaps that was once the case, but as far as I know there are no difficulties now. The bumblebee story persists as an urban legend. And it makes a nice metaphor for things that wo

Theory and practice

Published on 2011-05-13 07:18:28

Donald Knuth explains how he combines theory and practice: This has always been the main credo of my professional life. I have always tried to develop theories that shed light on the practical things I do, and I’ve always tried to do a variety

Casting out z’s

Published on 2011-05-12 17:49:59

“Casting out nines” is a trick for determining the remainder when a number is divided by nine. Just add the digits of the number together. For example, what’s the remainder when 3896 is divided by 9? The same as when 3+8+9+6 = 26 is

Command option patterns

Published on 2011-05-12 16:55:49

Here are some common patterns in Unix command options. This is a summary of the patterns Eric Raymond describes here. Option Typical meaning -a All, append -b Buffer,block size, batch -c Command, check -d Debug, delete, directory

Mythology

Published on 2011-05-12 08:00:35

Here are five posts on mythology, using the word “myth” three different ways. First, classical mythology: Why Shakespeare is hard to read Jupiter’s magic square Next, myth as a false idea: Two myths I learned in college: bathtub dra

Works well versus well understood

Published on 2011-05-10 13:19:48

While I was looking up the Tukey quote in my earlier post, I ran another of his quotes: The test of a good procedure is how well it works, not how well it is understood. At some level, it’s hard to argue against this. Statistical procedures ope

The dark side of linchpins

Published on 2011-05-10 06:57:09

Seth Godin uses linchpins as a metaphor for people who are indispensable. These people hold things together much as a physical linchpin holds together a mechanical system. But the metaphor works in a couple ways that I don’t believe the author

Move on to the next question

Published on 2011-05-09 10:30:46

Here’s a recent discussion from Math Overflow. Q: I have some data points and, when I plot them on R, it looks like a normal distribution. I want to know how well my data fits the normal distribution. What kind of test should I do? A: There&#

Weekend miscellany

Published on 2011-05-06 21:13:42

Visual thinking Doodle Revolution Napkin timeline resume Philosophy Meta-metaphors Computing Microsoft’s plans for C++ Software gardening Regulating general-purpose computers Why Adobe Reader needs so many updates Science Origin of ROY G BIV Th

Superficial convenience

Published on 2011-05-05 21:09:15

Here’s an interesting phrase: superficial convenience at the expense of real freedom This comes from the conclusion of the 1998 essay The Elements of Style: UNIX as Literature by Thomas Scoville. The author sums up his preference for UNIX cult

Platonic solids

Published on 2011-05-05 20:43:49

There are five Platonic (regular) solids: tetrahedron, 4 triangular sides hexahedron (i.e. cube), 6 square sides octahedron, 8 triangular sides dodecahedron, 12 pentagonal sides icosahedron, 20 triangular sides Each face of a Platonic solid must be

Total security

Published on 2011-05-05 08:00:35

“If you want total security, go to prison. There you’re fed, clothed, given medical care and so on. The only thing missing is freedom.” — Dwight D. Eisenhower

Jupiter’s magic square

Published on 2011-05-03 07:48:05

Albrecht Dürer’s engraving Melencolia I contains an interesting magic square toward the top right corner. Here’s a close-up of the magic square: The square has the following properties: Every row, column, and diagonal sums to 34. The

Jupiter’s magic square

Published on 2011-05-03 07:48:05

Deadly icosahedra

Published on 2011-05-01 13:50:08

From The Number Mysteries: Some of the deadliest viruses in the biological books — from influenza to herpes, from polio to the AIDS virus — are constructed using the shape of an icosahedron. An icosahedron is a regular solid with 20 trian

Deadly icosahedra

Published on 2011-05-01 13:50:08

Curious, exciting, and slightly disturbing

Published on 2011-04-30 17:11:32

This weekend I’ve been wrapping up unfinished projects. One of those projects was reading Kraken: The Curious, Exciting, and Slightly Disturbing Science of Squid. The book is exactly what you might expect from the title: a quirky little book ab

Curious, exciting, and slightly disturbing

Published on 2011-04-30 17:11:32

Weekend miscellany

Published on 2011-04-30 11:39:20

Techno life skills C. S. Lewis on humility Lessons from a social media fast Mathematical tombstones The human spirograph @SansMouse starts over with basic Windows and Ubuntu keyboard shortcuts on Monday, May 2.

Weekend miscellany

Published on 2011-04-30 11:39:20

Scripting and the last mile problem

Published on 2011-04-29 10:34:42

From Bruce Payette’s book Windows PowerShell in Action: Why do we care about command-line management and automation? Because it helps to solve the Information Technology professional’s version of the last mile problem. The last mile probl

Scripting and the last mile problem

Published on 2011-04-29 10:34:42

Where OO has succeeded most

Published on 2011-04-29 08:16:57

Eric Raymond makes an interesting observation on where object oriented programming has been most successful. The OO design concept initially proved valuable in the design of graphics systems, graphical user interfaces, and certain kinds of simulation

Where OO has succeeded most

Published on 2011-04-29 08:16:57

Numerical exceptions

Published on 2011-04-28 06:52:14

Someone sent me a question yesterday that boiled down to the difference between kinds of numeric exceptions. I’ll give my response below, but first a little background. Numeric exceptions occur when a computer does some operation on a number th

Numerical exceptions

Published on 2011-04-28 06:52:14

The myth of the Lisp genius

Published on 2011-04-26 06:50:08

I’m fascinated by the myth of the Lisp genius, the eccentric programmer who accomplishes super-human feats writing Lisp. I’m not saying that such geniuses don’t exist; they do. Here I’m using “myth” in the sense of

The myth of the Lisp genius

Published on 2011-04-26 06:50:08

Small concepts with enormous implications

Published on 2011-04-25 16:19:25

Interesting philosophical aside from a technical book: The software field — really, any scientific field — tends to advance most quickly and impressively on those few occasions when someone (i.e., not a committee) comes up with an idea th

Small concepts with enormous implications

Published on 2011-04-25 16:19:25

How much time do scientists spend chasing grants?

Published on 2011-04-25 07:00:45

Computer scientist Matt Welsh said that one reason he left Harvard for Google was that he was spending 40% of his time chasing grants. At Google, he devotes all his time to doing computer science. Here’s how he describes it in his blog post The

How much time do scientists spend chasing grants?

Published on 2011-04-25 07:00:45

Weekend miscellany

Published on 2011-04-22 16:25:32

Easter Was Easter originally a pagan holiday? Holy Week timeline Mark Tarver essays Hackers and fighters Why I am not a professor Humor Douglas Adams’ cookie story How to fix any computer Math The Euler Archive Leonardo da Vinci’s Mathema

History is strange

Published on 2011-04-21 04:10:10

From historian Patrick Allitt of Emory University: History is strange, it’s alien, and it won’t give us what we would like to have. If you hear a historical story and at the end you feel thoroughly satisfied by it and find that it perfect

Teaching Bayesian stats backward

Published on 2011-04-20 10:04:42

Most presentations of Bayesian statistics I’ve seen start with elementary examples of Bayes’ Theorem. And most of these use the canonical example of testing for rare diseases. But the connection between these examples and Bayesian statist

The first FORTRAN program

Published on 2011-04-20 08:09:26

The first FORTRAN compiler shipped this week in 1957. Herbert Bright gives his account of running his first FORTRAN program with the new compiler here. (Bright gives the date as Friday, April 20, 1957, but April 20 fell on a Saturday that year. It se

Learn one sed command

Published on 2011-04-19 07:03:15

You may have seen sed programs even if you didn’t know that’s what they were. In online discussions it’s common to hear someone say s/foo/bar/ as a shorthand to mean “replace foo with bar.” The line s/foo/bar/ is a compl

Third-system effect

Published on 2011-04-18 08:04:33

The third-system effect describes a simple system rising like a phoenix out of the ashes of a system that collapsed under its own complexity. A notorious ’second-system effect’ often afflicts the successors of small experimental prototype

Weekend miscellany

Published on 2011-04-15 19:58:03

Typography Two sites for identifying fonts in images The Olivetti typewriter Software development Living in the zone The Lisp Curse Introduction to computer science with Minesweeper Preserving (the memory of) documents Math and statistics Eigenfeet,

Personal organization software

Published on 2011-04-15 07:36:36

I’ve tried various strategies and pieces of software for personal organization and haven’t been happy with most of them. I’ll briefly describe my criteria and what I’ve found. My needs are fairly simple. I don’t need or

Significance testing and Congress

Published on 2011-04-14 08:55:51

The US Supreme Court’s criticism of significance testing has been in the news lately. Here’s a criticism of significance testing involving the US Congress. Consider the following syllogism. If a person is an American, he is not a member

A magic king’s tour

Published on 2011-04-13 17:28:22

After posting about a magic square made from knight’s tour, I wondered whether there are magic squares made from a king’s tour. (A king can move one square in any direction. A tour is a sequence of moves that lands on each square of a che

How insignificant is statistical significance?

Published on 2011-04-13 15:48:56

Luis Pericchi sent me a brief note commenting on the recent US Supreme Court decision involving statistical significance and medical reporting. Here is his paper, about a page and a half. How insignificant is statistical significance? (PDF)

Evaluating weather forecast accuracy: an interview with Eric Floehr

Published on 2011-04-12 07:00:48

Eric Floehr is the owner of ForecastWatch, a company that evaluates the accuracy of weather forecasts. In this interview Eric explains what his business does, how he got started, and some of the technology he uses. JC: Let’s talk about your bu

Slide rules

Published on 2011-04-11 12:24:52

Mike Croucher raises an important point for teachers: Are graphical calculators pointless? I think they are. I resented having to buy my daughter an expensive calculator when I could have bought her a netbook for not much more money. Calculators are

Atomic skills versus molecular skills

Published on 2011-04-09 20:47:02

Scott Adams has an essay in the Wall Street Journal today entitled How to Get a Real Education. He starts by saying the brightest students should get an academic education and the rest should learn entrepreneurship. I disagree. I don’t see why

Words that are primes base 36

Published on 2011-04-09 15:07:35

This morning on Twitter, Alexander Bogomolny posted a link to his article that gives examples of words that are prime numbers when interpreted as numbers in base 36. Some examples are “Brooklyn”, “paleontologist”, and “d

Weekend miscellany

Published on 2011-04-08 11:53:39

Productivity There’s no speed limit Three unexpected laws of simplicity Significance testing US Supreme Court xkcd Math Pictures, Probability, and Paradox The Möbius Gear Largest known prime by year Computing How to build a computer The Chuck

Forced to be simple

Published on 2011-04-08 09:40:28

From Paul Graham: When you’re forced to be simple, you’re forced to face the real problem. When you can’t deliver ornament, you have to deliver substance. Related posts: Confusing familiar with simple Rewarding complexity A little s

Picking classes

Published on 2011-04-06 11:13:56

Here’s a little advice to students picking electives. Consider taking classes in those things that would be hardest to learn on your own after you graduate. Taking the most advanced courses available in your major may not be the best choice. Pr

Picking classes

Published on 2011-04-06 11:13:56

A knight’s tour magic square

Published on 2011-04-06 07:00:42

This magic square was created by Leonhard Euler (1707-1783). Each row and each column sum to 260. Each half-row and half-column sum to 130. The square is also a knight’s tour: a knight could visit each square on a chessboard exactly once by fol

A knight’s tour magic square

Published on 2011-04-06 07:00:42

Mersenne primes and world records

Published on 2011-04-04 13:06:20

Here’s an interesting account of the largest known primes over time. Thanks to @mathematicsprof for pointing this out. Ever since 1952, the largest known prime has been a Mersenne prime, with one exception in 1989. One reason is that it is simp

Mersenne primes and world records

Published on 2011-04-04 13:06:20

Better for whom?

Published on 2011-04-04 09:30:32

Software generally gets better over time, but this does not mean it’s getting better and better every day in every way. Software quality has so many dimensions that it is impossible to make progress along every front with every release of every

Better for whom?

Published on 2011-04-04 09:30:32

Weekend miscellany

Published on 2011-04-01 20:39:32

Photography Aerial photographs of tulip fields Typography Highway sign typography Software development To go fast, do less If You’re Not Gonna Use It, Why Are You Building It? Math Sicherman Dice Steven Smale’s list of unsolved problems T

Weekend miscellany

Published on 2011-04-01 20:39:32

Saved by symmetry

Published on 2011-03-31 10:24:44

When I solve a problem by appealing to symmetry, students’ jaws drop. They look at me as if I’d pulled a rabbit out of a hat. I used think of these tricks as common knowledge, but now I think they’re common knowledge in some circle

Saved by symmetry

Published on 2011-03-31 10:24:44

Arrogant ignorance

Published on 2011-03-30 07:10:40

The following line continues the theme of appropriate scale from a few days ago. We identify arrogant ignorance by its willingness to work on too large a scale, and thus put too much at risk. This comes from the title essay of Wendell Berry’s c

Arrogant ignorance

Published on 2011-03-30 07:10:40

Software development and the myth of progress

Published on 2011-03-28 10:08:47

The word myth brings up images of classical mythology. From there it can be generalized a couple ways. One is any story that is not true. Another is a story, whether true or not, that embodies a system of belief. Sociologists use myth in the latter s

Software development and the myth of progress

Published on 2011-03-28 10:08:47

Suspicious definitions

Published on 2011-03-27 18:36:12

I’ve long been suspicious of speeches that revolve around idiosyncratic definitions. I was pleased to find this evening that C. S. Lewis shared this suspicion. But when we leave the dictionaries we must view all definitions with grave distrust.

Suspicious definitions

Published on 2011-03-27 18:36:12

Weekend miscellany

Published on 2011-03-26 08:42:32

Music The “Jimi Hendrix of South India” Science and engineering Solar panels and haute cuisine Why Fukushima made me stop worrying and love nuclear power Medicine What happens to doctors who think outside the box? New books LaTeX Beginner

Weekend miscellany

Published on 2011-03-26 08:42:32

Priorities

Published on 2011-03-25 06:02:24

From Merlin Mann: If you’ve got more than two priorities, you might as well think you have more than two arms. Related posts: Task switching Four reasons we don’t apply the 80/20 rule

Priorities

Published on 2011-03-25 06:02:24

From Merlin Mann: If you’ve got more than two priorities, you might as well think you have more than two arms. His quote reminded me of the dialog from this video on how a large company would design a stop sign. Client: If you look at page 16 i

Three Firefox 4 tips

Published on 2011-03-24 22:18:25

The latest version of Firefox, version 4.0, makes a few changes that take a little getting used to. The navigation bar is below the tabs by default. The “home” icon has moved from the left end of the navigation bar to the right. The litt

Three Firefox 4 tips

Published on 2011-03-24 22:18:25

Appropriate scale

Published on 2011-03-23 08:32:50

“Scale” became a popular buzz word a couple decades ago. Suddenly everyone was talking about how things scale. At first the term was used to describe how software behaved as problems became larger or smaller. Then the term became more wid

Appropriate scale

Published on 2011-03-23 08:32:50

Python for high performance computing

Published on 2011-03-21 08:47:16

William Scullin’s talk from PyCon 2011: Python for high performance computing. At least in our shop [Argonne National Laboratory] we have three accepted languages for scientific computing. In this order they are C/C++, Fortran in all its diale

Python for high performance computing

Published on 2011-03-21 08:47:16

Weekend miscellany

Published on 2011-03-19 07:55:16

Philosophy referee hand signals Virtual tour of Lascaux Deaths per unit of energy produced by coal, nuclear, etc. Algebraic surface gallery Magnetic lines of buckyballs (gorgeous images) What to demand from a scientific computing language PyCon 2011

Weekend miscellany

Published on 2011-03-19 07:55:16

Understanding radiation units

Published on 2011-03-18 11:59:29

Radiation units are confusing for three or four reasons. There are different units depending on whether you’re measuring how much radiation is being emitted or measuring how much is being received. There are different ways of quantifying the a

Understanding radiation units

Published on 2011-03-18 11:59:29

Daily tip accounts broader than names imply

Published on 2011-03-18 09:16:16

Some of my daily tip Twitter accounts are a little broader than their names imply. Account names need to be fairly short, so they can’t be too descriptive. Here are fuller descriptions of some of the accounts. TeXtip is primarily about typeset

Daily tip accounts broader than names imply

Published on 2011-03-18 09:16:16

Seven interviews

Published on 2011-03-16 11:38:53

Here are six people I have interviewed. Rick Richter, CIO of Food for the Hungry Robert Ghrist, applied topologist Carl Franklin, musician and software developer Frederick Brooks, computer pioneer and author Cliff Pickover, mathematician and author

Seven interviews

Published on 2011-03-16 11:38:53

A support one-liner

Published on 2011-03-15 11:11:45

This morning I had a fun support request related to our software. The exchange took place over email but it could have fit into a couple Twitter messages. Would that all requests could be answered so succinctly. Question: Do you have R code to comput

A support one-liner

Published on 2011-03-15 11:11:45

Work-life balance

Published on 2011-03-15 08:45:02

From Nigel Marsh: I stepped back from the workforce and I spent a year at home with my wife and four young children. But all I learned about work-life balance from that year was that I found it quite easy to balance work and life when I didn’t

Work-life balance

Published on 2011-03-15 08:45:02

Algorithm used for world record pi calculations

Published on 2011-03-14 09:45:46

The following algorithm is based on work of Ramanujan and has been used in several world-record calculations of pi. Initialize a0 = 6 – 4 √2 and y0 = √2 – 1. Then compute and The terms an form a sequence of approximations to 1/π. T

A Ramanujan series for calculating pi

Published on 2011-03-14 07:00:27

Ramanujan discovered the following remarkable formula for computing π: This is not the most efficient series for computing π. My next post will give a more efficient method, also based on work of Ramanujan. But the series above is interesting for

Digital workflow

Published on 2011-03-13 18:30:57

William Turkel has a nice four-part series of blog posts entitled A Workflow for Digital Research Using Off-the-Shelf Tools. His four points are Start with a backup and versioning strategy. Make everything digital. Research 24/7 (using RSS feeds). M

Engineers save millions of lives in Japan

Published on 2011-03-12 17:10:31

From Dave Ewing via Roberto Montagna: The headline you won’t be reading: “Millions saved in Japan by good engineering and government building codes”. But it’s the truth. The loss of life in Japan is tragic, but it would have

Weekend miscellany

Published on 2011-03-11 16:40:42

Science Dyson on heresy, climate change, and science What to demand from a scientific computing language Typography Ancient Christianity and punctuation Free math books Archimedes: The Sand Reckoner The Book of Proof Geometry of the Quintic Pauca sed

Marshall McLuhan reading technique

Published on 2011-03-09 18:51:14

From Douglas Copeland’s book on Marshall McLuhan: Marshall … didn’t have the patience to work through a book that didn’t interest him from the start. He even developed a technique to suit his impatience: whenever he picked up a ne

Sonnet primes

Published on 2011-03-08 20:08:56

The previous post showed how to list all limerick primes. This post shows how to list all sonnet primes. These are primes of the form ababcdcdefefgg, the rhyme scheme of an English (Shakespearean) sonnet, where the letters a through g represent digit

Limerick primes

Published on 2011-03-08 09:23:57

The other day, Futility Closet posted this observation: 10102323454577 is the smallest 14-digit prime number that follows the rhyme scheme of a Shakespearean sonnet (ababcdcdefefgg). I posted this on AlgebraFact and got a lot of responses. One was fr

Not enchanted with “Enchantment”

Published on 2011-03-08 07:00:02

I’ve read a fair number of business books, but I stopped reading them when they all started to sound alike. I have limited time for reading and so I want to read books that “blow my hair back” as Will Hunting would say. I made an ex

A little math puzzle

Published on 2011-03-07 15:58:50

Futility Closet posted the other day that log 237.5812087593 = 2.375812087593. Make a formal statement of the problem that 2.375812087593 solves and show that there’s exactly one other solution. Related posts: What does this code do? Tricky cod

Augustine, Leibowitz, and evolution

Published on 2011-03-07 12:22:59

The following paragraph is from the science fiction novel A Canticle for Leibowitz: A fourth century bishop and philosopher. He [Saint Augustine] suggested that in the beginning God created all things in their germinal causes, including the physiolog

Weekend miscellany

Published on 2011-03-04 12:05:12

Humor How to be a hipster Charlie Sheen v Muammar Gaddafi Math Galton’s Bayesian machine from 1877 “Mnemonic” is a mnemonic (Poisson density) Fibonacci matrix identity The Optimization Edge (Using optimization to run a business) Py

Thomas Jefferson and preparing for meetings

Published on 2011-03-03 09:50:00

Here’s an interesting historical anecdote from Karl Fogel’s Producing Open Source Software on the value of preparing for meetings. In his multi-volume biography of Thomas Jefferson, Jefferson and His Time, Dumas Malone tells the story of

Psychological encapsulation

Published on 2011-03-02 07:12:22

A piece of software is said to be encapsulated if someone can use it without knowing its inner workings. The software is a sort of black box. It has a well-defined interface to the outside world. “You give me input like this and I’ll prod

Singularity interview

Published on 2011-03-01 08:13:02

Vincent Tan interviews me in the March 2011 issue of his online magazine Singularity. One of the topics we discuss is the difference between studying applied math and actually applying math.

Programmers without computers

Published on 2011-02-28 06:57:55

When I started my first job as a programmer, I was surprised how much time my colleagues spent at their computers. Of course a computer programmer needs to spend a fair amount of time sitting at a computer, but why did people spend nearly 100% of the

Weekend miscellany

Published on 2011-02-26 09:09:49

Typography and design 11 important digital fonts The pilcrow Vintage posters Music Five seconds of every #1 hit song Hymnopedia Economics The Great Stagnation Make everyone hurt Computer humor An update is available for your computer How a programmer

Absence of evidence

Published on 2011-02-22 07:54:40

Here’s a little saying that irritates me: Absence of evidence is not evidence of absence. It’s the kind of thing a Sherlock Holmes-like character might say in a detective novel. The idea is that we can’t be sure something doesn̵

Scientific Python on Twitter

Published on 2011-02-21 14:14:08

Next week I’m starting a new daily tip Twitter account: @SciPyTip. This account will post on things related to scientific computing in Python, including the SciPy library, related software, and scientific computing in general. Full list of dai

Weekend miscellany

Published on 2011-02-18 13:00:20

Photography Egypt 1920s in color Productivity The 3/2 rule of employee productivity Computing NumPy array introduction IPv4 X-day arrived and no one died Music Against background music Adult culture Math Algebraic surfaces Ramanujan formulas for comp

Beatles 3000

Published on 2011-02-17 21:52:27

Here’s a documentary on The Beatles from 1000 years in the future: I sometimes wonder how much history and science has about as much connection to reality as this reconstruction of The Beatles. Related post: Paleolithic nonsense

Beatles 3000

Published on 2011-02-17 21:52:27

Here’s a documentary on The Beatles from 1000 years in the future: I sometimes wonder how much history has about as much connection to reality as this reconstruction of The Beatles. Related post: Paleolithic nonsense

Like Laplace, only more so

Published on 2011-02-17 09:21:59

The Laplace distribution is pointy in the middle and fat in the tails relative to the normal distribution.This post is about a probability distribution that is more pointy in the middle and fatter in the tails. Here are pictures of the normal and La

Like Laplace, only more so

Published on 2011-02-17 09:21:59

How the term “scientist” come to be

Published on 2011-02-16 06:50:22

For most of history, scientists have been called natural philosophers. You might expect that scientist gradually and imperceptibly replaced natural philosopher over time. Surprisingly, it’s possible pinpoint exactly when and where the term scie

How the term “scientist” come to be

Published on 2011-02-16 06:50:22

Art critics versus artists

Published on 2011-02-15 06:55:03

From Pablo Picasso: When art critics get together they talk about Form and Structure and Meaning. When artists get together they talk about where you can buy cheap turpentine. Related posts: Two videos on craftsmanship Doing good work with bad to

Art critics versus artists

Published on 2011-02-15 06:55:03

The end of hard-edged science?

Published on 2011-02-14 08:06:02

Bradley Efron says that science is moving away from things like predicting sunrise times and toward predicting things like the weather. The trend is away from studying precisely predictable systems, what Efron calls “hard-edged science,”

The end of hard-edged science?

Published on 2011-02-14 08:06:02

Final velocity

Published on 2011-02-12 21:03:01

My daughter and I were going over science homework this evening. A ball falls for 10 seconds. What is its final velocity? JC: So how fast is the ball going when it hits the ground? RC: Zero. It stops before it bounces back up. JC: Well, how fast is i

Final velocity

Published on 2011-02-12 21:03:01

Weekend miscellany

Published on 2011-02-11 13:00:58

Science Glass melts near absolute zero Bioengineered blood vessels Neal Stephenson essays What the strange persistence of rockets can teach us about innovation In the beginning was the command line Math History of non-Euclidean geometry Nineteen dubi

Weekend miscellany

Published on 2011-02-11 13:00:58

Ice on a spider web

Published on 2011-02-09 15:29:14

Photos of thawing ice on a spider web taken by my friend Jeff Farmer.

Ice on a spider web

Published on 2011-02-09 15:29:14

Photos of thawing ice on a spider web taken by my friend Jeff Farmer.

Why Food for the Hungry runs Ubuntu

Published on 2011-02-08 07:00:11

Rick Richter is CIO of Food for the Hungry. In this interview Rick explains why his organization is moving all of its computers to Ubuntu. John: Tell me a little about Food for the Hungry and what you do there. Rick: Food for the Hungry is a Christi

Why Food for the Hungry runs Ubuntu

Published on 2011-02-08 07:00:11

Twin prime conjecture and the Pentium division bug

Published on 2011-02-07 07:00:32

Twin primes are pairs of primes that differ by 2. For example, 3 and 5 are twin primes, as are 17 and 19. Importantly, so are 824633702441 and 824633702443. More on that in a minute. No one knows whether there is a largest pair of twin primes. The tw

Twin prime conjecture and the Pentium division bug

Published on 2011-02-07 07:00:32

Mac has gotten harder to use, Windows easier

Published on 2011-02-05 19:16:47

CHI Conversations has posted a talk by Jef Raskin, designer of the first Macintosh, entitled Macintosh: Lessons Learned, Lessons Lost. The talk was recorded in 2004, about a year before Raskin’s death. Much of the talk is devoted to Macintosh h

Mac has gotten harder to use, Windows easier

Published on 2011-02-05 19:16:47

Weekend miscellany

Published on 2011-02-04 14:44:47

Rap videos I’m reading a book Fear the Boom and the Bust, Sequel Computing C# interactive shell Studying the dangers of spreadsheets Computing efficiency trends Email as spectroscopy Snowstorm Snow in Houston Satellite photos of snowstorm Snowd

Weekend miscellany

Published on 2011-02-04 14:44:47

LEGO blocks and organ transplants

Published on 2011-02-03 11:09:37

People have been comparing software components to LEGO blocks for a couple decades. We should be able to assemble applications by snapping together modular components, just like LEGOs. There has been progress, but for the most part we haven’t r

LEGO blocks and organ transplants

Published on 2011-02-03 11:09:37

Keyboard shortcuts for Mac, Linux, and Windows

Published on 2011-02-03 07:12:30

As many of you know, I have a Twitter account @SansMouse that posts one Windows keyboard shortcut per day. I’m starting to experiment with adding Mac and Linux keyboard shortcuts as well. For Linux, I’ll stick to Ubuntu with the default G

Keyboard shortcuts for Mac, Linux, and Windows

Published on 2011-02-03 07:12:30

Interview with David Spiegelhalter

Published on 2011-02-02 22:25:33

Samuel Hansen interviews David Spiegelhalter on his mathematical podcast Strongly Connected Components. From the show notes: On today’s episode of Strongly Connected Components Samuel Hansen called up the Winton Professor for the Public Understand

Interview with David Spiegelhalter

Published on 2011-02-02 22:25:33

Top five pages

Published on 2011-02-01 07:08:58

Here are the most popular pages on this site that are not blog posts. Aside from the home page, the five most popular pages are: PowerShell cookbook R programming for those coming from other languages Diagram of probability distribution relationship

Top five pages

Published on 2011-02-01 07:08:58

Acupuncture and confirmation bias

Published on 2011-01-30 17:39:16

Here’s another excerpt from The decline effect and the scientific method that I wrote about a couple weeks ago. Between 1966 and 1995, there were forty-seven studies of acupuncture in China, Taiwan, and Japan, and every single trial concluded

Acupuncture and confirmation bias

Published on 2011-01-30 17:39:16

A motivational speaker with integrity

Published on 2011-01-29 12:37:35

I wonder how many motivational speakers live out their own advice. Of those who do, how many will continue to live out their advice as they raise a family? How many will continue to walk their talk into old age? Time has a way of exposing the hypoc

A motivational speaker with integrity

Published on 2011-01-29 12:37:35

Weekend miscellany

Published on 2011-01-28 20:02:41

Windows Microsoft gives jailbreakers schwag IronPython-based data/science environment Unix Unix as literature Computer science Nature-inspired algorithms Functional and imperative OOP Math Breakthrough in partition theory: paper, lecture Measure theo

Weekend miscellany

Published on 2011-01-28 20:02:41

Pilots and pair programming

Published on 2011-01-28 07:34:10

From Outliers by Malcolm Gladwell: In commercial airlines, captains and first officers split the flying duties equally. But historically, crashes have been far more likely to happen when the captain is in the “flying seat.” At first this

Pilots and pair programming

Published on 2011-01-28 07:34:10

When it works, it works really well

Published on 2011-01-27 07:30:37

Stephen Stigler [1] compares least-squares methods to the iPhone: In the United States many consumers are entranced by the magic of the new iPhone, even though they can only use it with the AT&T system, a system noted for spotty coverage —

Python-based data/science environment from Microsoft

Published on 2011-01-26 18:08:34

See Microsoft Research’s announcement of the the Sho project. Sho is an interactive environment for data analysis and scientific computing that lets you seamlessly connect scripts (in IronPython) with compiled code (in .NET) to enable fast an

Coming full circle

Published on 2011-01-25 06:55:39

Experts often end up where they started as beginners. If you’ve never seen the word valet, you might pronounce it like VAL-it. If you realize the word has a French origin, you would pronounce it val-A. But the preferred pronunciation is actuall

More theoretical power, less real power

Published on 2011-01-24 09:31:19

Suppose you’re deciding between two statistical methods. You pick the one that has more power. This increases your chances of making a correct decision in theory while possibly lowering your chances of actually concluding the truth. The subtle

Pseudo-commons and anti-commons

Published on 2011-01-22 22:31:38

Here are a couple variations on the tragedy of the commons, the idea that shared resources can be exhausted by people acting in their individual best interests. The first is a recent podcast by Thomas Gideon discussing the possibility of a tragedy of

Which Platonic solid best fills a sphere?

Published on 2011-01-22 16:25:01

Which of the five Platonic solids takes up the most volume when inscribed in a sphere? The answer may surprise you. See Pat’s Blog.

Weekend miscellany

Published on 2011-01-21 19:20:52

Public key cryptography before Diffie, Hellman, and Merkle New lighthouse in Washington Reflections on Eisenhower’s farewell address 30 Years of BAD Pictures from Bruce Dale on Vimeo.

Efficiency of regular expressions

Published on 2011-01-20 09:01:12

I’ve never optimized a regular expression. I typically use regular expressions in scripts where efficiency doesn’t matter. And sometimes I do some regular expression processing as part of a larger program in which the bottleneck is some

A couple preprints

Published on 2011-01-20 08:47:51

Here are a couple new preprints. Block-adaptive randomization. A proposed method for limiting the size of runs in a response-adaptive clinical trial. Skeptical and optimistic robust priors for clinical trials. Joint work with Jairo Fúquene and Luis

Fitting an elephant

Published on 2011-01-18 11:27:11

“With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.” — John von Neumann Related post: Occam’s razor and Bayes’ theorem

Hanlon’s razor and corporations

Published on 2011-01-18 09:03:56

Hanlon’s razor says Never attribute to malice that which is adequately explained by stupidity. At first it seems just an amusing little aphorism, something you might read on a bumper sticker, but I believe it’s profound. It’s a guid

Daily tips update

Published on 2011-01-17 08:00:24

RegexTip, a Twitter account for learning regular expressions, starts over today with basics and will progress to more advanced properties over time. SansMouse, an account for Windows keyboard shortcuts, started over with basics two weeks ago. Both Re

Scientific results fading over time

Published on 2011-01-17 07:12:15

A recent article in The New Yorker gives numerous examples of scientific results fading over time. Effects that were large when first measured become smaller in subsequent studies. Firmly established facts become doubtful. It’s as if scientific

Weekend miscellany

Published on 2011-01-15 07:58:19

Music Sacred classical music Free Bach organ recordings Programming Why you can’t hire great Perl programmers 65 attempts at resolving P versus NP Math Math blogs: MathBlogging.org Dynamical systems on a plane Exotic spheres ESP and statistics

Your job is trivial. (But I couldn’t do it.)

Published on 2011-01-14 08:47:40

Ever had a conversation that could be summarized like this? Your job is trivial. (But I can’t do it.) This happens in every profession. Everyone’s job has difficulties that outsiders dismiss. I’ve seen it in everything I’ve do

How long computer operations take

Published on 2011-01-12 08:00:43

The following table is from Peter Norvig’s essay Teach Yourself Programming in Ten Years. All times are in units of nanoseconds. execute typical instruction 1 fetch from L1 cache memory 0.5 branch misprediction 5 fetch from L2 cache me

Occam’s razor and Bayes’ theorem

Published on 2011-01-12 04:00:53

Occam’s razor says that if two models fit equally well, the simpler model is likely to be a better description of reality. Why should that be? A paper by Jim Berger suggests a Bayesian justification of Occam’s razor: simpler hypotheses ha

Occam’s razor and Bayes’ theorem

Published on 2011-01-12 04:00:53

Demand for simplicity?

Published on 2011-01-11 07:17:02

From Donald Norman’s latest book Living with Complexity: … the so-called demand for simplicity is a myth whose time has passed, if it ever existed. Make it simple and people won’t buy. Given a choice, they will take the item that does m

Demand for simplicity?

Published on 2011-01-11 07:17:02

Some programmers really are 10x more productive

Published on 2011-01-10 06:19:41

One of the most popular post on this site is Why programmers are not paid in proportion to their productivity. In that post I mention that it’s not uncommon to find some programmers who are ten times more productive than others. Some of the com

Some programmers really are 10x more productive

Published on 2011-01-10 06:19:41

Another math calendar from Ron Doerfler

Published on 2011-01-09 08:30:46

Last year Ron Doerfler made a beautiful calendar with images from graphical computing, charts used as computational aids before desktop calculators were ubiquitous. Ron has made a new calendar and this year’s theme is lightning computing, trick

Another math calendar from Ron Doerfler

Published on 2011-01-09 08:30:46

Weekend miscellany

Published on 2011-01-07 13:17:41

Computing The wonderful world of early computing How to design programs Twitter Twitter accounts for all StackOverflow users by reputation and area Science Elementary mechanics from a mathematician’s viewpoint Using ultrasound to study dying la

Weekend miscellany

Published on 2011-01-07 13:17:41

Computing The wonderful world of early computing How to design programs Twitter Twitter accounts for all StackOverflow users by reputation and area One fact per day from computer science, math, statistics, etc. Science Elementary mechanics from a ma

Three views of differential equations

Published on 2011-01-07 07:46:34

The most common view of differential equations may be sheer terror, but those who get past terror may have one of the following perspectives. Naive view: All differential equations can be solved in closed form by applying one of the 23 tricks covered

Three views of differential equations

Published on 2011-01-07 07:46:34

Obscenity

Published on 2011-01-06 08:18:11

Classical Greek dramatists believed that it was degrading to show extreme emotion on stage. Some action had to be implied off stage (ob skene) because it was unfit to display explicitly. The classical idea of obscenity included sexual conduct, but wo

Obscenity

Published on 2011-01-06 08:18:11

Three P’s and three I’s of economics

Published on 2011-01-06 05:03:35

In the December 27 episode of EconTalk, Pete Boettke summarizes basic economics as follows: If you don’t have the three P’s, you can’t have the three I’s. The three P’s are Property Prices Profit and loss The three I&#

Three P’s and three I’s of economics

Published on 2011-01-06 05:03:35

Style and understanding

Published on 2011-01-05 17:07:35

From Let Over Lambda by Doug Hoyte: Style is necessary only when understanding is missing. A corollary to this is that sometimes the only way to effectively use something you don’t understand is to copy styles observed elsewhere. I liked those

Style and understanding

Published on 2011-01-05 17:07:35

Mathematical landscape

Published on 2011-01-03 19:54:35

W. W. Sawyer makes a beautiful analogy regarding the mathematical landscape in his book Prelude to Mathematics. Imagine farmers living in a country where no other tool was available except the wooden plough. Of necessity, the farms would have to be i

Mathematical landscape

Published on 2011-01-03 19:54:35

Educating versus credentialing

Published on 2011-01-03 08:54:28

“Colleges aren’t really in the education business. Colleges are in the credentialing business.” — Josh Kaufman Of course colleges would like to educate students along the way, but ultimately they are in the business selling cr

Educating versus credentialing

Published on 2011-01-03 08:54:28

The solar system in a glass of wine

Published on 2011-01-01 10:23:33

William Blake’s poem Auguries of Innocence opens with these famous lines: To see a world in a grain of sand, And a heaven in a wild flower, Hold infinity in the palm of your hand, And eternity in an hour. This poem came to mind when I saw @math

The solar system in a glass of wine

Published on 2011-01-01 10:23:33

Two contrasting articles on minimalism

Published on 2011-01-01 08:57:02

This morning I ran across a couple articles on minimalism: Minimalism is NOT a viable intellectual strategy (30 Dec 2010) Minimalism IS a viable long term intellectual strategy (31 Dec 2010) The former has a sense of humor; the latter does not. The

Two contrasting articles on minimalism

Published on 2011-01-01 08:57:02

Weekend miscellany

Published on 2010-12-31 10:18:23

Math Geometrical and topological analogues of Rubik’s Cube Chessboards and colorings Three remarkable geometry theorems Literature Recordings of all extant poems in Old English Theology Why December 25 is Christmas Vocation versus Churchianity

Weekend miscellany

Published on 2010-12-31 10:18:23

The bipolar Internet

Published on 2010-12-28 10:49:54

In a recent Atlantic article, Jaron Lanier discusses the bipolar nature of the Internet. The Internet … was influenced in equal degrees by 1960s romanticism and cold war paranoia. It aligned the two poles of the bit to these two archetypal dram

Dumb and gets things done

Published on 2010-12-27 09:37:16

Someone once asked Napoleon how he decided where to assign soldiers. Napoleon’s reply was that it’s simple: soldiers are either smart or dumb, lazy or energetic. The smart and energetic I make field commanders. They know what to do and c

Weekend miscellany

Published on 2010-12-23 16:06:46

Life One small thing Technology giveth, technology taketh away One way to keep from stuff you don’t have Science IceCube Neutrino Observatory Niagara Falls without water Möbius Symmetry in Metamaterials John Conway Generating primes with the G

Reading as inclination leads

Published on 2010-12-23 09:15:09

The following quote has stuck in my mind for many years: A man ought to read just as inclination leads him: for what he reads as a task will do him little good. I first ran across the quote in Spivak’s Calculus in college and have largely follo

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