> | deq1:=diff(x(t),t)=a1*x(t)*(1-b1*y(t));deq2:=diff(y(t),t)=a2*y(t)*(x(t)-b2); |
> | with(DEtools): |
> | a1:=1; a2:=0.3; b1:=1; b2:=1; |
> |
> | DEplot([deq1,deq2], [x(t),y(t)],t=-7..7,[[x(0)=1.2,y(0)=1.2],[x(0)=1,y(0)=.7]],stepsize=.2, title=`Lotka-Volterra model`,color=[.3*y(t)*(x(t)-1),x(t)*(1-y(t)),.1], linecolor=t/2,arrows=MEDIUM,method=rkf45); |
> |