Archives for cp's mathem-o-blog

Newcastle MathsJam October 2012 Recap

Here’s my recollection of what happened at October’s Newcastle MathsJam. It was a fortnight ago and I’m trying to write quickly, so it might be missing a few things.

Newcastle MathsJam October 2012 Recap continued »

Slides from a talk about zero-knowledge protocols

I’ve just given a talk at Newcastle’s maths & stats Postgraduate Forum about zero-knowledge protocols. I don’t know very much about them but it’s an interesting topic and something fairly accessible to an audience of non-pure mathematicians.

Click here to see the slides.

I used deck.js, along with the Computer Modern web fonts and MathJax, to make the slides. I think it looks pretty nice! I’ve also uploaded my template deck, in case you want to build on it for your own presentations. It’s a bit big because it contains all the files needed to display the Computer Modern fonts on any browser.

Newcastle MathsJam September 2012 Recap

Hey, I haven’t done one of these in absolutely ages! I’ve missed two MathsJams and forgot to write up the other two, so that’s why that’s the case.

September’s MathsJam was very enjoyable. We had some magic tricks, debated the application of game theory to the penal system, almost played a game of rhythmomachy, and of course we solved a few puzzles.
Newcastle MathsJam September 2012 Recap continued »

Using Computer Modern on the web

Computer Modern is the family of typefaces developed by Donald Knuth for TeX. It’s so good-looking that some scientists do research just so they can write it up in Computer Modern.

The cm-unicode project compiles versions of the Computer Modern fonts in a few formats, including TTF. I’ve run them through codeandmore’s @font-face kit generator to get all the weird formats that the various browsers insist on.

I’ve put up a page containing examples of each face in use and links to packages containing everything you need to use them.

Carnival of Mathematics 88

Better late than never, here’s the 88th Carnival of Mathematics. As an editor of The Aperiodical, I’ve been press-ganged into interrupting my holiday to write this month’s edition.

Before I start with the real submissions, I think I’ll abuse this bully pulpit to link to some of my recent blogging efforts. I found each letter’s favourite words, recorded a video proving a nice fact about grids of fibonacci numbers, and wrote an Aperiodical Round Up. I also wrote a jQuery and WordPress plugin to give blog commentors instant previews of LaTeX in their comments. You can try that in the comments section here, if you’d like.

Katie Steckles has submitted a few article from the Math Goes Pop! blog: a review of the book Math Puzzles, some discussion of how you rank baseball teams, and a guest post on CNN’s light years blog about how professors’ dads made math fun. An anonymard has also sent in a piece from the same site on the half-your-age-plus-seven rule for finding a socially acceptable mate.

Alexander Bogomolny has sent in a solution to a puzzle from the 2008 Moscow Olympiad, featuring a crooked polygon.

Colm Mulcahy wrote a very interesting article for his Maths Colm on The Aperiodical, musing on the question: In what flipping dimension is a square peg in a round hole just as good as a round peg in a square hole? He has also written about the mind-bogglingly huge number of ways there are of shuffling a deck of cards.

Shecky R. has sent in a review of Gregory Chaitin’s new book, Proving Darwin, about his algorithmic information theory.

Samuel Hansen wrote a great piece on his and Peter Rowlett’s Second-Rate Minds blog about the moment that turned him “from a civilian into a mathematician”.

Andrew Taylor muses on the statistics of behindness in National Novel Writing Month.

Peter Rowlett has written on his blog Travels in a Mathematical World asking whether anniversaries are worth celebrating. A hint to how he feels might be found in the existence of the Math/Maths 100th episode/2nd birthday spectacular.

Øistein Gjøvik lets loose some toilet thoughts on learning.

Gianluigu Filippelli has written a really great article about Alan Turing’s work on morphogeenesis.

Finally, Peter Krautzbeger sent in his 11 dreams for the publishing debate.

That’s it! That’s everything I was sent this month. To submit something for next month’s Carnival, which will be hosted by Katie Steckles at The Aperiodical, visit the Carnival’s homepage.

Instant MathJax preview of LaTeX typed into HTML textareas

I’ve completely rewritten my write maths, see maths library to be a little jQuery plugin that attaches itself to editable areas on pages, like contenteditable elements, textareas, and input boxes. When your cursor is inside some LaTeX, a little preview box appears just above it with the LaTeX rendered through MathJax. I’ve made a demo page on GitHub, and the code itself is available there too. It also works in TinyMCE, if you’re into that sort of thing.

The first I thing I did with it was to write a WordPress plugin which applies the plugin to the comment boxes underneath posts (source code). I’ve installed it on this site and The Aperiodical, so you can use LaTeX with confidence, knowing that it’ll appear how you want on the page. Please try it in the comments box below!

A huggermuggering nonannouncement of an overinvolved knickknack

It’s odd, the process of waking up. Sometimes you can get out of bed and stumble around for an hour or two, maybe even get dressed and go to work, before your brain does anything to differentiate you from a patient in a highly mobile vegetative state. On other days it seems that your mental starter motor catches on the first try and before you’ve even opened your eyes all sorts of brilliantly original thoughts are competing for attention.

Today is one of those days. As I swung my big long legs out of bed the thought occurred to me that the word “cheese” has an awful lot of Es in it. (“Brilliantly original” is of course a subjective description, but this is my story so I say it qualifies). I wondered what word has the most Es in it. Now we’re beginning to move towards a decent notion. A huggermuggering nonannouncement of an overinvolved knickknack continued »

Fibonacci Grids

I uploaded this video to YouTube last week but I forgot to make a post here. It’s about a moderately interesting fact about fibonacci numbers that David Cushing told me at MathsJam. I generalised it a bit, so I’ve been meaning to write a post for The Aperiodical or do a snappy video or something like that for ages.

I finally decided last week to just sit down and record myself going through the proof, so here’s that video. I deliberately didn’t prepare beforehand, so it’s just under an hour long and contains a lot of thinking out loud.

Converting a stream of binary digits to a stream of base $n$ digits

James Coglan asked on twitter:

So you have an infinite stream of uniform random binary digits, and want to use it to produce an infinite stream of uniform random base $n$ digits.

The obvious really easy way to do it is to find the smallest $k$ such that $2^k>=n$, and generate numbers in the range $0 \dots 2^k-1$.

If the number you generate is less than $n$, yield it, otherwise chuck it away.

This works, but has the problem that you might go a long time before you generate a number that you don’t throw away.

So what can we do with the numbers that are thrown away?

Subtract $n$ from them, and use them as a stream of infinite base $(2^k-n)$ digits.

You can then do the same trick of generating enough of those digits until you can generate numbers greater than or equal to $n$. Numbers less than $n$ are yielded; otherwise, the trick is repeated yet again! Converting a stream of binary digits to a stream of base $n$ digits continued »

Problems I’m currently thinking about

I’ve been in a bit of a problem-posing mood recently. Hopefully I’ll do some problem-solving soon. Here are a few questions I’ve thought of but haven’t got solutions for. I haven’t done any literature searching, so these might have been done before.

All the problems are quite computery. Maybe I’m a computer scientist, really. Problems I’m currently thinking about continued »