Fractint

Detail of the Mandelbrot set When I was writing an article on the Mandelbrot set, I looked for software to generate illustrations. Needless to say that there is lots of stuff available for a colorful subject like that. But, lo and behold, I discovered that the venerable Fractint still exists, and is actually still maintained! The program…

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Submitted on 1 May 2012

Where to Launch Your Rocket?

If you want to launch a rocket into space, as I’m sure practically all of you are at least contemplating, where should you do that? The main thing is of course to avoid populated areas, to limit the damage if the thing blows up. The launch pad itself should be located away from people, and there should be a large uninhabited region to the east of the launch site…

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Submitted on 10 April 2012

Infinity and Beyond

If you think about a set with an infinite number of elements, you might conclude that there is not much to say about the number of elements anymore. Infinite is infinite, right? Well, it turns out that not every infinity has the same “value”, and that there’s actually quite a lot to say about it. Take the natural numbers…

Submitted on 26 March 2012

QR Codes

QR code structure

You have probably already encountered a few QR codes. These codes are becoming more and more common, and can be found on business cards, ads, historical buildings, T-shirts, etc. You're meant to scan them using your smartphone. They can contain all sorts of information, the most common being plain text, URLs, and contact information. The information is… [This article contains a demo in which you can create your own QR codes!]

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Submitted on 25 October 2011

Beware of Silently Assuming Linear Intensity in Astronomical Images

Demo of the effect of screen gamma

This article points out the danger of assuming that astronomical images are encoded using linear intensity. It is meant for the many people that are performing astronomical observations using regular cameras. Not because there’s something wrong with that, but because those cameras are optimized for “normal” photography and video, not for numerical calculations on their images. The illustration below…

Submitted on 17 September 2011

What's in a Distance

The distance between two points is a concept that is, in every day use, clear and unambiguous. Mathematically, the normal (every day) distance between two points is called the Euclidean distance, but mathematicians generalize this definition. I show how, and I try to make you think by showing how circles look using some of these alternative definitions…

Submitted on 6 July 2011