> with(plots):

Warning, the name changecoords has been redefined

> with(DEtools):

> DEplot([diff(x(t),t)=y(t),diff(y(t),t)=-2*x(t)+8*x(t)^3],[x(t),y(t)],-1.5..1.5,{[0,.3,0],[0,-.5,0],[0,0,.3],[0,0,.5],[0,0,.6],[0,.52,0]},color=y^2+2*x^2-4*x^4,arrows=THICK,stepsize=.1,linecolor=black,title=`Soft oscillator, color=2*energy`);

>