Gerrys Attraction

Gerry's Attraction is a freeware 3D visualizer by Gerry Beggs that renders the Lorenz and Rossler strange attractors in real time on the classic Mac. Inspired by Hiroki Mori's BeOS Lorenz Attractor, it lets you fly through the curling trajectories using familiar Marathon- or Quake-style controls.

Strange attractors in 3D

The program plots a cloud of points on the xy plane and integrates them through the Lorenz or Rossler equations, so the characteristic butterfly and spiral shapes emerge as the simulation runs. The visualization updates continuously, giving a tangible feel for how nearby trajectories diverge.

Fly the equations

Rather than presenting the attractor as a static plot, Gerry's Attraction lets you steer a free camera around and through the evolving curves. The control scheme is borrowed from first-person shooters of the era, which makes inspecting the geometry from any angle quick and intuitive.

Full-screen QuickTime mode

If QuickTime is installed, the application can switch into a full-screen mode that turns the attractor into a screen-filling demo. It is well suited to classroom or lecture use where a large, animated example of deterministic chaos is more illustrative than a textbook diagram.

Version 1.3 compatibility fix

The 1.3 release noted in the Info-Mac upload corrects a problem that prevented earlier builds from launching on systems older than Mac OS 8.5, broadening the range of classic Macs that can run the simulation.

Freeware with a friendly request

Beggs released the software as freeware, asking only that CD-ROM redistributors send him a copy or let him know the program is being included. There is no nag screen and no time limit on use.