Toy windmill on a roundabout.

InitGraph(); ScaleWindow(-2,-2,2,2); DrawAxes(); tmax=10; Colour(Red); Label('Top view',-1.2,1.2); Colour(Green); Label('Side view',-1.2,1.0); dt=.0013 LineStart(1.1,0); StepModel();
//function StepModel() x = (1 + 0.1* Math.cos(20*pi*t))* Math.cos(2*t); y = (1 + 0.1* Math.cos(20*pi*t))* Math.sin(2*t); z = 0.1*Math.sin(20*pi*t); t = t + dt; Colour(Red); Spot(x,y); Colour(Green); Spot(x,z); t=t+dt; if (t<tmax){ setTimeout('StepModel()',10); }else{Label('Stopped',1.2,1.2);};