# 3

> ode1 := diff( y(t), t ) = v(t) :

> ode2 := diff( v(t), t ) = -7*y(t) - 8*v(t) :

> MODEL := [ ode1, ode2 ] ;

> VAR := { y(t), v(t) } ;

>

> DOMAIN := t = 0 .. 3 ;

> WINDOW := y = -2 .. 2,

> v = -2 .. 2 ;

>

> IC := [ y(0)=1, v(0)=0 ];

> PHASEplot := DEplot( MODEL, VAR, DOMAIN, [ IC ], WINDOW,

> arrows=SLIM,

> scene=[ y, v ], linecolor=BLUE,

> title = `Phase Portrait for # 3` ):

> PHASEplot;

>

> P1:= DEplot( MODEL, VAR, DOMAIN, [ IC ],

> scene=[ t, y ], arrows=NONE, linecolor=BLUE ):

> P2:= DEplot( MODEL, VAR, DOMAIN, [ IC ],

> scene=[ t, v ], arrows=NONE, linecolor=GREEN ):

> display( [ P1, P2 ] , title = `y and v solution curves for # 10` );

>