Happy Birthday: Leonhard Euler

Today is Leonard Euler’s 300th birthday. Or it would be, if he was still alive!

Born on 15 April 1707, Euler was a Swiss mathematician. He was prolific and made lots of contributions to geometry, trigonometry and calculus that abacus-wielding blog readers might be familiar with.

• He invented the idea of using i to denote .
• He popularised using π to denote the ratio of a circle’s circumference to its diameter.
• He introduced e to represent the base of the natural logarithm, sometimes known as Euler’s number (or Napier’s constant).

But maybe he’s best remembered (by me at least) for Euler’s identity which is an incredible formula. It has a feeling of completeness: beautiful and perfectly formed.

Richard Feynman called it “the most remarkable formula in mathematics” for “its single uses of the notions of addition, multiplication, exponentiation, and equality, and the single uses of the important constants 0, 1, e, i, and π”.

It’s also the only piece of mathematics that I’ve had to prove from first principles since graduating from university. During an afternoon coffee break ten years or so ago, a summer student in work (who did engineering rather than applied maths), wondered how it could be proved. One paper napkin later, happy student. But my maths has faded, so don’t ask for a repeat performance.

In the days of yore, PCs in work had fixed IP addresses, and if you got in quickly enough, you could choose the hostname for the machine. (If you weren’t quick, someone in the central team looking after the PCs would have assigned it the next name off their list of epidemics, which included influenza, cholera, typhus, smallpox, but stopped short of necrotizing fasciitis.)

So in order to pay homage to my mathematics heritage, I named my first PC (a Zenith 50MHz Intel 486, pre-Pentium!) euler. We also had an einstein and a faraday on the floor. For the next ten years, I transferred the name euler to each new PC, until hostnames became a thing of the past.

But Leonard Euler … many happy returns. (And thanks to Paul Robinson over at the Novice Philosopher for the timely reminder.)