Phase Plane Demo for Matlab
Discussion of the latest features by the author John Polking.
Description
This demo provides a means to interactively look at the phase plot of a
user defined system of two ODEs. The first screen presents you with a
sample system which you can modify along with a couple other options.
Alternatively you can select from several predefined systems in the
"Gallery" menu. Predefined systems available are
- a linear system
- vibrating spring
- a pendulum
- Predator-Prey
- Competing Species
- Van der Pol's Equation
- Duffing's Equation.
Once a system is chosen click on proceed and a second window will pop up
with the phase portrait of your system. Click on a point in this plot
and the solution which passes through that point will be graphed both
forward and backward in time. Many options are also available from this
screen. You can
- Plot several solutions at once
- Zoom in/out
- Find Equilibrium points
- List computed Equilibrium points
- Place text on the plot
- Print graph
- and a few others.
Instructions for Use
- Create the directory: MATLAB
- Use either xdir
- the Unix and DOS command mkdir MATLAB
- or, your favorite file management program.
- Copy the files dfield.m, dfsolve, pplane.m, and ppsolve.m into the MATLAB directory you created
above.
- Simply use whatever method is used in your Web browser to
download files and put them into your MATLAB directory.
- Alternative, the latest version can be accessed through the
Rice Univeristy ftp site.
- Macintosh versions are available at the ftp site.
- Start up Matlab
- On our system this can be done by simply typing
matlab at the prompt or from the menus
Root Menu -> Programs -> MATLAB
- Get into your MATLAB directory.
- cd MATLAB, for example.
- When inside the MATLAB session simply type the command
pplane
- ENJOY!
Interactive Differential Equations
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