Exercise 3
Wheldon's model of chronic granuloctic leukemia [8] has
the form



a 1 + b y_{1}(tt)^{g}

 
l y_{1}(t) 1 + m y_{2}(t)^{d}


 


l y_{1}(t) 1 + m y_{2}(t)^{d}

 w y_{2}(t) 


Code the equations for general values of the parameters
to make it easy to experiment with the model. Remember that if you
do not set any options, you must use a placeholder of []
for the options argument. Solve the problem on [0,200]
with history y_{1}(t) = 100, y_{2}(t) = 100 for t £ 0 and
parameter values a = 1.1 ×10^{10},b = 10^{12},g = 1.25, d = 1, l = 10, m = 4 ×10^{8}, w = 2.43 that you set in the main program. Compare
the solutions you obtain with t = 7 and t = 20 . You
could code this as
for tau = [7, 20]
sol = dde23('exer3f',tau,...
...
end
You should find that the solution is oscillatory in both cases. In
the first, the oscillations are damped quickly and in the second,
they are not.
Reference
 [8]

N. MacDonald, Time Lags in Biological Models,
SpringerVerlag, Berlin, 1978.