Monthly Archives: March 2012

tl;dr

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

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Posted in Creativity

How Emacs influenced Ruby

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.

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Posted in Software development

Numerous studies have confirmed …

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

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Posted in Business, Statistics

Polynomial determined by two inputs

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.

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Posted in Math

Photo quiz: What's this?

What do think the object on the left is? (The chair is only in the photo for a sense of scale.)

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Debugging code running 100 million miles away

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.

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Numerical integration trick

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

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Posted in Math

Math is like the Hawaiian islands

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

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Posted in Math

SciPy integration misunderstanding

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

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Posted in Python

Nicolas Bourbaki's wedding invitation

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

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Posted in Math

Easiest and hardest classes to teach

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

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Posted in Math, Statistics

Software to slice bread

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

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Posted in Software development

Digital desk, analog desk

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

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Misplaced decimal

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

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iPad as hip flask

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

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