"The Ponytail Shape Equation represents the first scientific understanding of the distribution of hairs in a ponytail...."

"It provides new understanding of how a bundle is swelled by the outward pressure which arises from collisions between the component hairs. Together with a new mathematical quantity known as the Rapunzel Number, the equation can - they say - be used to predict the shape of any ponytail.... This will resonate with some in the computer graphics and animation industry, where a realistic representation of hair and fur has proven a tough challenge."

BBC reports.