function [value,isterminal,direction] = bounceEvents(t,y)
value = y(1);     % Detect height = 0
isterminal = 1;   % Stop the integration
direction = -1;   % Negative direction only

tstart = 0;
tfinal = 30;
y0 = [0; 20];
refine = 4;
options = odeset('Events',@events,'OutputFcn',@odeplot,'OutputSel',1,...
  'Refine',refine);

fig = figure;
ax = axes;
ax.XLim = [0 30];
ax.YLim = [0 25];
box on
hold on;

tout = tstart;
yout = y0.';
teout = [];
yeout = [];
ieout = [];
for i = 1:10
  % Solve until the first terminal event.
  [t,y,te,ye,ie] = ode23(@f,[tstart tfinal],y0,options);
  if ~ishold
     hold on
  end
  % Accumulate output.  This could be passed out as output arguments.
  nt = length(t);
  tout = [tout; t(2:nt)];
  yout = [yout; y(2:nt,:)];
  teout = [teout; te];          % Events at tstart are never reported.
  yeout = [yeout; ye];
  ieout = [ieout; ie];
 
  ud = fig.UserData;
  if ud.stop
     break;
  end
 
  % Set the new initial conditions, with .9 attenuation.
  y0(1) = 0;
  y0(2) = -.9*y(nt,2);
 
  % A good guess of a valid first timestep is the length of the last valid
  % timestep, so use it for faster computation.  'refine' is 4 by default.
  options = odeset(options,'InitialStep',t(nt)-t(nt-refine),...
     'MaxStep',t(nt)-t(1));
 
  tstart = t(nt);
end

plot(teout,yeout(:,1),'ro')
xlabel('time');
ylabel('height');
title('Ball trajectory and the events');
hold off
odeplot([],[],'done');