function Nov25()

% Here is the slope function used by ode45
function yp = f(t,y)
rabbits = y(1)
foxes = y(2)
yp = [2*rabbits-alpha*rabbits*foxes ;...
      -foxes+alpha*rabbits*foxes]
  
% Here is the function we hand over to fzero...

function z = F(r0,T)
[tVal,yVals] = ode45(@f,[0,T],[r0;10])
rabbitFinal = yVals(length(tVals),1);
z = rabbitFinal-200