Phase Portrait

To create a plot similar to Figure 2.33 we consider initial conditions taken on a regular grid of the window. Here is one way to do this (it's basically a nested "do" loop)

> IC := seq(

> seq(

> [x(0)=0.5*i, y(0)=0.5*j ],

> j=0..4 ),

> i=0..4 ) ;

> DEplot( MODEL, VAR, DOMAIN, [ IC ], WINDOW, stepsize=0.25, # try it without the stepsize option

> scene=[ x, y ], arrows=MEDIUM, linecolor=BLUE,

> title = `Figure 2.33` );

>