Figures 3.2 and 3.4

> ode1 := diff( x(t), t ) = -x(t) + 4*y(t);

> ode2 := diff( y(t), t ) = -3*x(t) - y(t);

> MODEL := { ode1, ode2 }:

> VARS := { x(t), y(t) }:

> DOMAIN := t=0..4:

> RANGE := x=-2..2, y=-2..2:

> IC := [ [ x(0)=2, y(0)=0 ] ]:

> dirPLOT := DEplot( MODEL, VARS, DOMAIN, RANGE, arrows=MEDIUM ):

> #dirPLOT;

> solPLOT := DEplot( MODEL, VARS, DOMAIN, RANGE, IC, arrows=NONE, stepsize=0.1, linecolor=GREEN ):

> #solPLOT;

> display( [ dirPLOT, solPLOT ], title=`Figure 3.2` );

>

> xPLOT := DEplot( MODEL, VARS, DOMAIN, IC, scene=[t,x], arrows=NONE, stepsize=0.1, linecolor=GREEN ):

> yPLOT := DEplot( MODEL, VARS, DOMAIN, IC, scene=[t,y], arrows=NONE, stepsize=0.1, linecolor=BLUE ):

> display( [ xPLOT, yPLOT ], title=`Figure 3.4` );

>