Flex 4.5+

The DiffEQPlotter explores graphical solutions to differential equation systems. Nine equation system families are provided - some simple algebraic systems, some ecology models, and some limit cycles. Each can be tuned by setting constants. Paired time plot and phase plot show the behavior of the system (trajectory) from any selected starting point. The phase plot also shows the "nullclines" (where the derivative of each equation is zero), and a vector field showing the tendency of the system across a grid over the plane.

Though not "fractals" software, it was developed for the same mathematics professor, Michael Frame of Yale University.

Pattern Blocks are used in early math and just for fun. Great for drawing mandalas, tilings, and tesselations. Originally written as a toy for my daughter in 1998, this is my most popular app by a landslide. Latest version features full-browser resizing, better email, hundreds of backgrounds, and keystroke shortcuts. Now with Art Gallery for kid-safe sharing!

Mandalar is PatternBlocks for mobile! PatternBlocks is now released as a mobile app. See Mandalar. Still in Adobe Flex - all web/mobile platforms are cross-operable.

SimWatershed is loosely based on the real-life Esopus Creek watershed, part of the naturally-cleaned water supply of New York City. SimWatershed implements two online labs, for the Yale School of Forestry graduate course Science to Solutions: How Should We Manage Water.

In the "Biophysics" lab, students explore how water quality is affected by adjusting land use - suburban, agricultural, livestock, and forest. Then in the "Solutions" lab, buying land costs money and faces limits. Other social treatments are available at a price: best management practices, upgrading the local sewage treatment plant, raising prices, or building a city water treatment plant. Scenarios explore present and future, nitrogen and sediment.

Download the "Solutions" lab instructions.