On stage his agonised expressions resembled 'a professor grappling with an inordinately complex equation', according to one critic.

Two female students, hunched over complex equations at a nearby table, take no notice.

They are complex equations, even for scientists used to complexities.

Cells of other shapes require much more complex equations.

They allow more complex surfaces to be represented by a series of relatively simple equation sets rather than a single set of complex equations.