# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Computing at the Edge: Capturing a flame's flicker, an ink jet's splatter,and other shifting shapes," by Ivars Peterson. *Science News,* 10 April1999, pages 232-234.

The surface of a breaking wave is jagged and rapidly changing. It is an ofexample turbulent behavior that can result from forces acting at the boundarybetween two different materials. This complicated behavior is difficult todescribe mathematically. This article describes a new approach being used tomodel such situations. Called the level-set approach, it involves modeling thetwo-dimensional boundary as part of a three-dimensional surface. It turns outthat from the three-dimensional perspective, the changes in the boundary aresmoother. The method is being used to detect edges in scanned medical images,model the growth of crystals, and create special effects for movies.

*--- Elizabeth Moisan*