This page lists three phase plane plotters listed in java. They all work in approximately the same way, but some may work better on some computers than others. I suggest starting with the xFunctions resizable window phase plane plotter, since it is the most flexible. The xFunctions plotters may not work on Macs running Netsacpe 4 and earlier. Try using Internet Explorer. If it doesn't work try the fixed size xFunctions plotter or Scott Herod's phase plane plotter.
The resizable xFunctions phase plotter
The plotter (most convenient)
Here is a quick summary of how to plot a direction field using this plotter:
- Click on "the plotter" above.
- When the next page appears, wait for the "launch xFunctions" button to load. Depending on circumstances this might take many seconds while the java applet is downloaded.
- Click on the button labeled "Launch xFunctions"
- When the plotting window appears, click and hold on the "main screen" bar at the top of the window and select "integral curves utility".
- To get started, enter dx/dt = 1 (near the bottom of the screen) -- this makes the t variable and the x variable the same.
- Enter your equation on the last line, for example dy/dt = y or dy/dt =y +x. (Remember that you have made t and x equal, so the second example is really dy/dt = y +t. Unfortunately the constraints of the computer program only allow the variables x and y to be entered.
- If you want, you can also enter pairs of equations such as dx/dt = x +y and dy/dt = x-y. This allows you to plot simple examples of simultaneous differential equations.
Detailed Instructions for using xFunctions
The fixed size xFunctions phase plotter
Fixed plotterInstructions for using xFunctions
Additional phaseplane plotters
A phase plotter by Scott Herod (most compatible with older browsers)