Here are a few ways you can contact me. mail@johndcook.com @JohnDCook The Endeavour johndcook1 Endeavour Selections Profile Profile

Here are a few ways you can contact me. mail@johndcook.com @JohnDCook The Endeavour johndcook1 Endeavour Selections Profile Profile

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My favorite topic in an introductory differential equations course is mechanical and electrical vibrations. I enjoyed learning about it as a student and I enjoyed teaching it later. (Or more accurately, I enjoyed being exposed to it as a student…

I’ve run across a couple web sites that let you enter a LaTeX symbol and get back its Unicode value. But I didn’t find a site that does the reverse, going from Unicode to LaTeX, so I wrote my own.…

Mental Floss had an interesting article called 12 letters that didn’t make the alphabet. A more accurate title might be 12 letters that fell out of the modern English alphabet. I thought it would have been better if the article…

I’ve read Richard Hamming’s essay You and Your Research a couple times and took it to heart. But I didn’t know until this morning that there is a video of Hamming giving his talk. Hat tip to Nuit Blanche. As…

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It’s a simple rule of probability that if A makes B more likely, B makes A more likely. That is, if the conditional probability of A given B is larger than the probability of A alone, the the conditional probability…

I had a little fun on Twitter this morning. From @UnixToolTip I said Some of the best programmers use Emacs. Therefore, if you use Emacs, you’ll be a great programmer. #cargocultlogic and from @CompSciFact I said Some of the best…

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I started Endeavour Selections on Facebook a little over a year ago for people who want to read the non-technical posts here but who are not so interested in math or computing. The page didn’t take off, so I stopped…

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How do you take the Fourier transform of a function when the integral that would define its transform doesn’t converge? The answer is similar to how you can differentiate a non-differentiable function: you take a theorem from ordinary functions and…

I recently read a math book in which delimiters never adjusted to the size of their content or the level of nesting. This isn’t unusual in articles, but books usually pay more attention to typography. Here’s a part of an…

I saw a tweet this morning from Patrick Honner pointing to a blog post asking how you might teach derivatives of sines and cosines differently. One thing I think deserves more emphasis is that “co” in cosine etc. stands for…

Here’s an image that came out of something I was working on this morning. I thought it might make an interesting border somewhere. The blue line is sin(x), the green line 0.7 sin(φ x), and the red line is their…

This afternoon Hadley Wickham gave a great talk on data analysis. Here’s a paraphrase of something profound he said. Visualization can surprise you, but it doesn’t scale well. Modelling scales well, but it can’t surprise you. Visualization can show you…

From Thinking, Fast and Slow: Experts who acknowledge the full extent of their ignorance may expect to be replaced by more confident competitors who are better able to gain the trust of clients. I believe Hanlon’s razor applies here: ignorance…

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A couple days ago I wrote a blog post quoting Cal Newport suggesting that four hours of intense concentration a day is as much as anyone can sustain. That post struck a chord and has gotten a lot of buzz…