Closed for Summer (2015)


Comes again the time where the semester comes to an end. Students are busy with finals and various assignments, professors are busy with marking finals and assignments. Soon it will be over and I will concentrate on research and publication. I have this thing I’ve been trying to finish for a few months now—still just a few days more, just a few days more—and new stuff I want to start. So I will neglect, like last year, the blog until September, where I will return with the normal, once-a-week or almost, posting schedule.

(Dalia, 2560×1440)

(Dalia, 2560×1440)

A runcible nonce


In the recent panic surrounding the Heartbleed bug, we ask ourselves why, and how, these bugs still happen. We know that it was a preventable bug, with a simple fix, but with potentially important repercussions.


The bug is explained in non-technical (but accurate) terms here, and the patch is shown here. But that’s not what I want to talk you about. Let’s discuss the source of the problem.

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A random Golden Ratio Appears!


Well, we all make errors once in a while, but sometimes they’re more interesting than others. So I inadvertently forgot a square in a calculation and the series suddenly started converging, to the most beautiful of convergences of all: \phi.


So, let’s see how I got the golden ratio to emerge from a broken algorithm.

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Best. Number Base. Ever.


One of the first things we learn when we begin programming is that there are different number bases: base 10, the usual one, but also binary, octal, and hexadecimal. Their expressive power is strictly equivalent, but we also notice that hexadecimal numbers are written much more compactly than binary, and so, hexadecimal is “more efficient.”


But “efficiency” begs the question: how do we define it, and, once efficiency defined, which base is the best? Let’s find out!

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Glass Tardis


A good friend of mine and his wife just had a beautiful baby girl, and I wanted to give them something different. Turns out, the mom is a big fan of Dr Who and so I had the idea of making a stain-glass Tardis nightlight.

So I looked around the interwebs to find a couple of pictures of the Tardis to get the scale/ratio right, and set to cut glass:

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Bad Graphs!


One of the good things of the peer review process is that if you publish, you’re eventually going to have to review papers for conferences or journal in your (perceived) area of expertise. Sometimes you get pearls such as “the resulting results of algorithm X are resulted” (true story), or “the dynamics of the attorney of yes no plasmodium” (also true), but sometimes bad science comes from the bad presentation of results.

This is also a (essentially true) story. So I’m reviewing a paper that proposes some kind of method for predicting the value of (some) parameter that minimizes some error function. The method is fast, but not analytic. The graph in the paper looks something like:

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Artsy Recycling: follow-up


A while ago I wrote to my mayor to ask for better recycling of electronics and other technological items in my home town. The mayor responded rapidly with good news!

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Les Anciens


Contrairement à ce que croyaient les Anciens Grecs, le rôle de la science n’est pas de fignoler des représentations délectables, mais de prendre l’Univers comme elle le trouve.

Marcel Boll

Histoire des mathématiques

Herding Cats


I’m sure you’ve heard the expression herding cats before. When you’re trying to manage programmers, the expression certainly comes to mind. What if programmers were cats, which one would you be?

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Wallpaper: The Color of NOT having Backups


(The Color Of NOT Having Backups, 1920×1200)

You can find more wallpapers here