Phase Portrait

> IC := seq( seq( [x(0)=i/2, y(0)=j/2], j=-2..2 ), i=-2..2 );

> DEplot( MODEL, VAR, DOMAIN, [ IC ], WINDOW,

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

> title = `Partially Decoupled System` );

>