# October, 2012

Or, how the biggest company in the world is built on matrices. As with most Flying Colours Maths Blog articles, I don’t claim any kind of historical accuracy. The details are likely to be wrong, but I’m not one to let the truth get in the way of the story;

## Secrets of the Mathematical Ninja: How to be a g-whizz

The gravitational constant, as has been drilled into your head repeatedly, is 9.8 metres per second squared. It’s usually easiest to do all your sums with a $g$ in (I find it better to write $12g$ rather than 117.6, especially when the $g$s all cancel out) — but sometimes, you

## Silly Questions Amnesty

Crikey, where did October go? That's an example of a Silly Question, on which I'm currently having an amnesty, because it's Friday and that's when I hold a Silly Questions Amnesty. Send me questions. I'll answer them.

## Quotable Maths: Smith

Pure mathematics, may it never be of any use to anyone. - HJS Smith

## Book Review: Euler’s Gem, by David S Richeson

When Barney lent me this book, he asked me if I could explain what topology was for. In honesty? Despite my thesis title being “The Magnetic Topology Of The Solar Corona”, I couldn’t — I only studied topology because my PhD boss told me I should. I hoped that reading

## The Lives of the Mathematical Ninja: Bourbaki

Nicolas Bourbaki published a series of books in the middle of the 20th century, in an attempt to put maths on a firmly rigorous footing. So far, so completely antithetical to Mathematical Ninjary, which is all about getting good answers quickly without worrying too much about the details. But there’s

## Silly Questions Amnesty

You know the drill by now, surely? It's Friday. Send me questions. You can drop me an email at colin@flyingcoloursmaths.co.uk if you'd rather not leave it in the comments.

## Quotable maths: Krishna

It is magic until you understand it, and it is mathematics thereafter - Bharati Krishna

## Why is the dot product the way it is?

(Thanks to Barney Maunder-Taylor for teasing me with this one.) This question interests me for two reasons: Firstly, it's a neat proof in its own right, and I'll start by giving a little sketch of it. Secondly, though, even after Barney gave me the crux of the proof, it still

## Secrets of the Mathematical Ninja: Sine and cosine (part II)

So why do some angles give you exact answers and some not? I'm not going to answer that today. Another time. Today, I'm just going to tell you how to remember the key values, the ones that live on your set square. You can make an argument that the sine