Introductory Programming
Fall 2005

For today you should have

1) reviewed Chapter 3

2) prepared for an Evaluation

Today

1) Evaluation 5

2) discussion of Evaluation 4


Functions
---------

A model of the execution of a function

1) evaluate the argument (which is an expression)

2) assign the resulting value to the input variable

3) run the body of the function

4) the value of the output variable is the return value

5) replace the original function call with the return value

6) resume whatever you were doing when you got to the
   function call.


Evaluation 4
------------

You can download my solution from http://wb/ip/code/mice.m

a = 0.9;
B = [70 36 11 1 4 13 28 43 56] * 1e-4;
t0 = 0;
tend = 8;    % months
n = 1000
dt = (tend - t0) / n;

t = zeros(1, n+1);   % time
N = zeros(1, n+1);   % mouse population

t(1) = t0;
N(1) = 900;    

for i=2:n+1
    t(i) = t(i-1) + dt;
    index = floor(t(i-1)+1);
    b = B(index);
    dN = dt * (a * N(i-1) - b * N(i-1) ^ 1.7);
    N(i) = N(i-1) + dN;
end

plot(t, N)
peak = max(N)