l=30; r=0.55;q=8;c=1; f[x_]:=r x (1-x/q)-x^2/(1+x^2); modell={u'[s]==v[s], v'[s]==-c v[s] - f[u[s]],u[0]==u0,v[0]==v0}; p:={loesung=NDSolve[modell,{u,v},{s,0,l}]; abb=ParametricPlot[Evaluate[{u[s],v[s]}/.loesung],{s,0,l}, DisplayFunction->Identity, PlotPoints->50]}; max1=30; max2=10; dimu=2; dimv=1.0; bild1a=Table[{u0=dimu i/max1;v0=dimv;p},{i,0,max1}]; bild1b=Table[{u0=0;v0=dimv j/max2;p},{j,0,max2}]; bild1c=Table[{u0=dimu i/max1;v0=-dimv;p},{i,0,max1}]; b1=Show[Evaluate[bild1a,bild1b,bild1c], DisplayFunction->$DisplayFunction,PlotRange->All,AxesLabel->{"u","v"},ImageSize->{400,300}];