a=0.2; modell={r'[t]==r[t] (a-r[t]) (r[t]-1), w'[t]==1, r[0]==r0, w[0]==0}; tmax=50; p:={loesung=NDSolve[modell,{r,w},{t,0,tmax},MaxSteps->500]; bild=Plot[Evaluate[{r[t] Cos[w[t]]}/.loesung],{t,0,tmax}, PlotRange->All, DisplayFunction->Identity, AxesLabel->{"t","x"}]}; r0=0.199; p; bild1=bild; r0=0.201; p; bild2=bild; Show[bild1]; Show[bild2]; bild3=Show[bild1,bild2,DisplayFunction->$DisplayFunction, ImageSize->{400,300}];