April 26, 2013
I think it is fairly intuitive that the smiley in the title is upside down. But why is this?
Generally, when we look at a face we look at the eyes first. These days it is pretty easy to track where people look, the equipment is cheap and easily available – one simply uses a camera to look at the pupil and then calculates where the subject is looking. A preference for beginning with the eyes is a widely observed phenomenon (‘eyes are special’).
English readers, like readers in most languages, scan left to right when reading. With reading we constantly train ourselves to prefer moving left to right, something which leads to a phenomenon often called a readers bias (see this). It is not only during reading that the direction from left to right is preferred.
So, it is not surprising that we should think that smilies with eyes on the left are correct: left to right is preferred for reading, and eyes to mouth is preferred for viewing faces.
July 1, 2012
For a while now I have had an interest in information geometry. The maxims that geometry is intuitive maths and information theory is intuitive statistics seem pretty fair to me, so it’s quite surprising to find a lack of easy to understand introductions to information geometry. This is my first attempt, the idea is to get an geometric understanding of the mutual information and to introduce a few select concepts from information geometry.
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March 13, 2012
Not the usual kind of topic, but this needs to go out into the wide world. How to print the annotations that sometimes one might get on a pdf file:
First install or upgrade Adobe Reader to 9.0:
sudo apt-get install acroread
sudo apt-get upgrade acroread
Then back up and open the following file in your home directory: “~/.adobe/Acrobat/9.0/Preferences/reader_prefs”
cp reader_prefs reader_prefs.backup
gedit will complain about the encoding, but ignore it and click “edit anyway” (we have a backup if anything goes badly wrong). Find the bit where it says:
/printCommentPopups [/b false]
and change “false” to “true”. Save the file. So it looks like
/printCommentPopups [/b true]
Now you can just open up your file in adobe reader
and print, making sure to select the “Documents and Markups” option in the “Comments and Forms” combo box in the print dialogue.
February 1, 2012
As of the midnight at the turn of the month:
January 31, 2012
Looking through the recent petition/vow making against the commercial nature of academic journals (http://thecostofknowledge.com/) I couldn’t help notice a fairly strong subject area bias. So, I scraped the subject area fields of the website and made this pretty graph:
But what does it mean?
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December 25, 2011
A team using advanced brain analyzers have discovered the true nature of Christmas. Using cutting-edge technology along with very very complicated statistics they have proved that Christmas lies entirely between our ears.
The experimenters at Lapin University placed a number of subjects into an expensive brain scanning machine and showed them a series of stimuli that invoked festive responses. When shown the stimuli the neurons in two parts of the midbrain – known as the corpus visci and corpus vini – lit up like a Christmas trees.
“We’ve found the grandmother neuron… but for Christmas!” said senior scientist Dr. Joulupukki – referring to the neurons that light up when you see your grandmother. “I call them the Grandfather Christmas neurons”, he quipped before a sustained period of forced laughter.
Some of the stimuli used by Joulupukki et. al.
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December 23, 2011
The song, Twelve days of Christmas raises a number of important questions, like who gives milkmaids as presents? and will this song ever end? But most importantly, it makes us ask: If every day was a day of Christmas (like some may wish), would it still be physically possible to sing the song?
Here’s how long it took to sing each verse on the John Peel show one year when the great man was still alive:
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December 22, 2011
Calculation of greatest common divisors is a quite complex problem for a digital computer, but not for pendulums:
The pendulums line up at the edge with frequencies given by the common divisors of their individual frequencies. For example, here is diagram of a 6Hz and a 4Hz signal, you can see that they line up with a frequency of 2Hz:
The algorithm it solves it is thought to be NP (it gets slow pretty quickly). Even though the problem it solves is difficult in the usual sense, the python code to calculate it is actually quite short (though I have deliberately made it so here):
return a if b == 0 else gcd(b, a%b)
December 13, 2011
I’ve been reading this article in the independent: “Proofs of God in a photon”. The article is ultimately about some anthropic principle stuff. But the comments are full of silly things that make reluctant to call myself a scientist in case I am associated with the authors. So, as therapy, I shall call a number of the commenters on their bullshit. First, a well meaning guy called Dan,
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