Solu tion Curves
> Xplot := DEplot( MODEL, VAR, DOMAIN, [ IC ],
> scene=[ t, x ], linecolor=BLUE ):
> Yplot := DEplot( MODEL, VAR, DOMAIN, [ IC ],
> scene=[ t, y ], linecolor=GREEN ):
> display( [ Xplot, Yplot ], title=`Solution Curves for #12(d)` );
>