Starting DStool

This document makes use of the program DStool to create phase portraits which give the user an opportunity to visualize the dynamical system.

Press the button marked Launch DStool to start DStool.

Next, use the left mouse button to bring up a menu next to the word model, and select the Parser.

Now, use the left mouse button to bring up a menu in the parser window and select file |> load file..
and load the file mutual.ds for the mutualism system or
child.ds for the predator-prey with child care system.

When the system appears, just click on the build button and you're ready to make phase portraits.

Using DStool

Once you have the system loaded, go to the selected point window and set the values for the parameters.

Throughout the documents suggested values for parameters are given in brackets. For instance,

[Phase Portrait:{a,c,e,f} = {1,2,1,1}] means:

set a equal to 1
set c equal to 2
set e equal to 1
set f equal to 1

Next, move to the large view window and click on a point with the left mouse button to select it and then click the middle mouse button to draw a trajectory starting at that point.

Repeat this many times to get a complete visual picture of the system.

Also note that in some portaits you may want to change the x or y range at the top of the view screen.