# Christopher J. Sangwin

On 1st October 2013 I moved to take up a post at Loughborough University.

## Software Projects

 STACK STACK provides a question type for the Moodle quiz which is specifically designed to enable sophisticated computer-aided assessment in Mathematics and related disciplines, with emphasis on formative assessment. DragMath DragMath is a free "drag and drop" equation editor, written in Java. The editor lets users build up mathematical expressions in a traditional two dimensional way, and then output the results in a correctly formed syntax.

## Publications

 Euler's sum One of my favourite results in mathematics is the following: $1 + \frac{1}{4} + \frac{1}{9} + \cdots = \frac{\pi^2}{6}.$ Leonard Euler's wild and brave explanation is given here. The game of Hex Hex is a connection strategy game for two players. It is simple to learn, great fun to play and has some deep mathematics behind it. Some hex resources. Stacking up dominoes Apparently you can stack up dominoes in balance in the following way To see how click here (PDF). Roller which are not round! Look at the picture below. It shows two `rollers' in the shape of a 50p with a book on top. What will happen to the vertical distance between the book and the table as you roll the book along? Normal vibration modes of a circular membrane Imagine an elastic circular membrane fixed along its circular boundary but otherwise free to vibrate. There are a number of different normal vibration modes which are possible. Click here for more details. The double pendulum A double pendulum consists of two rigid arms that are joined by a low friction bearing. Details are here.